Sheet Metal Flashing and Trim

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−---

−title: Sheet Metal Flashing and Trim

−category: Building Envelope

−toc_depth: 3

−description: >

− When to use: Shop- and field-formed architectural sheet metal that completes the building envelope: counterflashings and base flashings at the roof-to-wall interface, copings on parapets, gravel stops and fasciae at unparapeted roof edges, gutters and downspouts, scuppers and conductor heads, wall flashings (through-wall, head, sill, and pan flashings at masonry and stucco), expansion-joint covers, and miscellaneous closure trim. Covers prefinished galvanized steel, Galvalume (Al-Zn alloy-coated steel), aluminum, copper, zinc, and stainless steel fabricated per the SMACNA Architectural Sheet Metal Manual, including joint type, cleat type and spacing, expansion-joint provisions, hemming, ANSI/SPRI ES-1 wind-uplift compliance at roof edges, sealant and fastener selection, and dissimilar-metal isolation.

− Not intended for: Single-ply membrane roofing field membrane and integrated edge metal supplied as part of a manufacturer's NDL roof warranty package ([[sync/membrane-roofing]]); below-grade waterproofing terminations ([[sync/below-grade-waterproofing]]); structural standing-seam metal roof panels (use a metal roofing standard); preformed metal wall panel systems and rainscreen cladding; gutters and downspouts integral to a unitized rainscreen panel system; lightning protection air terminals and conductors; HVAC sheet metal ductwork; rough carpentry blocking and wood nailers supporting sheet metal (see structural and rough-carpentry standards). Above-grade wall thermal insulation behind sheet metal trim is covered by [[sync/building-thermal-insulation]].

−---

−

−# Scope {toc}

−

−## This standard covers the materials, design basis, fabrication, and installation of architectural sheet metal flashing and trim that completes the watertight building envelope at roof edges, parapets, wall penetrations, and material transitions. {note}

−## The sheet metal addressed here is a system of formed metal pieces — copings, counterflashings, base flashings, gravel stops, fasciae, gutters, downspouts, scuppers, conductor heads, through-wall flashings, head and sill flashings, expansion-joint covers, and closure trim — whose joinery, cleating, hemming, and expansion-joint detailing are designed and installed per the SMACNA Architectural Sheet Metal Manual. {note}

−

−## The SMACNA Architectural Sheet Metal Manual is the foundational industry reference for this work; this standard is read together with SMACNA's current edition and does not duplicate the geometric pattern details that the SMACNA manual already provides. {note}

−

−## Sheet metal flashing is interface work: most pieces live at the seam between two systems — roof and wall, wall and window, parapet and roof, or an expansion joint between two structural bays — so the performance of every piece depends on the dimensional accuracy of the adjacent construction and on a sequencing plan that places the sheet metal at the correct point in the construction order. {note}

−

−## A coping cap that is otherwise correctly fabricated will fail if it is set on out-of-level blocking, undersized for the parapet width, or installed after the membrane base flashing has been cut short on the inside face of the parapet. {note}

−

−## The Contractor shall verify dimensions and substrate conditions before fabrication.

−## The Contractor shall coordinate sequencing with the roofing, masonry, framing, and cladding trades.

−

−## The roof-edge subset of this work — copings, gravel stops, fasciae, and drip edges — is also wind-design-critical, and IBC Section 1504.5 requires that low-slope roof-edge metal be tested and labeled per ANSI/SPRI ES-1. {note}

−

−## Roof-edge metal that does not carry an ES-1 classification meeting the design wind pressure shall not be installed; this requirement is not waivable.

−## Where the project's roof is governed by FM Global insurance, FM Approval (FM 4435) for the roof-edge metal is additionally required.

−## Copings or edge metal that are field-fabricated on site without an ES-1 listing for the as-built profile and securement shall be either replaced with an ES-1-listed product or engineered and tested for the project conditions before installation.

−

−## Counterflashings, wall flashings, gutters, downspouts, and trim that do not function as roof-edge wind securement are not subject to ES-1 but shall comply with the cleat, fastener, and joint provisions in SMACNA for resistance to wind, thermal movement, and water infiltration.

−

−## The Contractor responsible for this scope shall have prior experience with the specified metal type.

−## Soldering of copper, lead-coated copper, and stainless steel shall be performed by trained operators; welding of aluminum and stainless steel shall be performed by qualified welders; and brake-formed shop work in heavier gauges of steel and stainless shall be performed by a fabricator with appropriate brake capacity.

−## The Contractor shall identify the fabricator and submit fabricator qualifications as part of the action submittal package.

−

−# Referenced Standards {toc}

−

−## The latest adopted edition of the following standards governs unless a specific edition is cited as controlling by the Authority Having Jurisdiction or the Owner. {note}

−

−| Standard | Title |

−|----------|-------|

−| SMACNA Architectural Sheet Metal Manual | Current edition — foundational reference for joint, cleat, hem, and expansion-joint details |

−| ANSI/SPRI/FM 4435/ES-1 | Wind Design Standard for Edge Systems Used with Low Slope Roofing Systems |

−| FM 4435 | Approval Standard for Edge Systems Used with Low Slope Roofing Systems |

−| ASTM A653/A653M | Standard Specification for Steel Sheet, Zinc-Coated (Galvanized) or Zinc-Iron Alloy-Coated (Galvannealed) by the Hot-Dip Process |

−| ASTM A792/A792M | Standard Specification for Steel Sheet, 55% Aluminum-Zinc Alloy-Coated (Galvalume) by the Hot-Dip Process |

−| ASTM A240/A240M | Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels and for General Applications |

−| ASTM A480/A480M | Standard Specification for General Requirements for Flat-Rolled Stainless and Heat-Resisting Steel Plate, Sheet, and Strip |

−| ASTM B370 | Standard Specification for Copper Sheet and Strip for Building Construction (cold-rolled and tempered) |

−| ASTM B69 | Standard Specification for Rolled Zinc |

−| ASTM B209/B209M | Standard Specification for Aluminum and Aluminum-Alloy Sheet and Plate |

−| AAMA 2605 | Voluntary Specification, Performance Requirements and Test Procedures for Superior Performing Organic Coatings on Aluminum Extrusions and Panels (70% PVDF / Kynar 500) |

−| AAMA 2604 | Voluntary Specification, Performance Requirements and Test Procedures for High Performance Organic Coatings on Aluminum Extrusions and Panels (50% PVDF) |

−| AAMA 2603 | Voluntary Specification, Performance Requirements and Test Procedures for Pigmented Organic Coatings on Aluminum Extrusions and Panels (commercial polyester) |

−| AAMA 611 | Voluntary Specification for Anodized Architectural Aluminum |

−| ASTM A924/A924M | Standard Specification for General Requirements for Steel Sheet, Metallic-Coated by the Hot-Dip Process |

−| ASTM A153/A153M | Standard Specification for Zinc Coating (Hot-Dip) on Iron and Steel Hardware (fasteners) |

−| ASTM F1667 | Standard Specification for Driven Fasteners: Nails, Spikes, and Staples |

−| ASTM C920 | Standard Specification for Elastomeric Joint Sealants (urethane, silicone) |

−| ASTM D1056 | Standard Specification for Flexible Cellular Materials — Sponge or Expanded Rubber (closed-cell butyl tape) |

−| ASTM E2140 | Standard Test Method for Water Penetration of Metal Roof Panel Systems by Static Water Pressure Head |

−| ASCE 7 | Minimum Design Loads and Associated Criteria for Buildings and Other Structures |

−| IBC | International Building Code — Sections 1503 (Roof Drainage), 1504 (Performance Requirements), 1505 (Fire Classification), 1503.6 and 1504.5 (Roof Edge Securement) |

−| NRCA Roofing Manual | Membrane Roof Systems (architectural sheet metal flashing details) |

−| FGIA (formerly AAMA) | Standards for architectural finishes and dissimilar-metal isolation |

−| SSINA Designer Handbook | Specialty Steel Industry of North America — Stainless Steel Fabrication and Finishing |

−| Copper Development Association — Copper in Architecture Handbook | Standard reference for copper sheet metal design and detailing |

−

−## Where conflict exists between referenced standards, the more stringent requirement shall govern unless the Designer of Record directs otherwise in writing.

−

−# Submittals {toc}

−

−## Action Submittals {toc}

−

−### The Contractor shall submit the following for the Designer of Record's review and approval before procuring materials, fabricating sheet metal pieces, or beginning installation.

−

−- Product data sheets for each metal type, confirming the applicable ASTM specification, base-metal thickness or gauge, coating designation (e.g., G90, AZ50), alloy and temper, and finish (mill, prepainted PVDF/SMP, anodized, batch-coated)

−- Manufacturer's published finish system data, including AAMA 2605 or AAMA 2604 conformance for prepainted coil and panel, AAMA 611 conformance for anodized aluminum, and warranty terms

−- ANSI/SPRI ES-1 test report and listing for each roof-edge profile (coping, gravel stop, fascia, drip edge), confirming the tested wind pressure equals or exceeds the design edge-zone pressure from ASCE 7; FM 4435 approval listing where FM Global insurance governs

−- Shop drawings showing each fabricated piece in plan, section, and elevation with dimensions, gauges, joint locations, cleat type and spacing, expansion-joint locations, hem details, and corner geometry; shop drawings shall reference the corresponding SMACNA detail plate where applicable

−- Layout drawings showing the location of every shop joint, expansion joint, cleat run, downspout, scupper, and conductor head on the building elevations

−- Color samples and finish samples on the actual specified metal substrate, of sufficient size to evaluate color, gloss, and texture in natural daylight; for prepainted coil, a minimum 12 inch by 12 inch sample for each color

−- Fabricator qualifications, including past project references for the metal type and joint methods specified

−- Sealant compatibility certifications between the specified sealant and the specified metal finish, including any pre-treatment requirements for adhesion to PVDF coatings

−- Cut list and yield plan for copper, zinc, and stainless steel scopes, demonstrating that pan widths and seam locations match the SMACNA detail being specified

−

−```datasheet

−label: Action Submittals Required

−type: checkbox

−options:

− - "Product data sheets for each metal type (ASTM spec, gauge, coating, alloy/temper, finish)"

− - "Manufacturer's finish system data (AAMA 2605/2604/611 conformance, warranty terms)"

− - "ANSI/SPRI ES-1 test report and listing for each roof-edge profile (FM 4435 where required)"

− - "Shop drawings (plan, section, elevation; joints, cleats, expansion joints, hems, corners)"

− - "Layout drawings (shop joints, expansion joints, cleat runs, downspouts, scuppers, conductor heads)"

− - "Color and finish samples on actual specified substrate (12 in x 12 in minimum for prepainted coil)"

− - "Fabricator qualifications with project references for metal type and joint methods"

− - "Sealant compatibility certifications (including PVDF pre-treatment requirements)"

− - "Cut list and yield plan for copper, zinc, and stainless steel scopes"

−default:

− - "Product data sheets for each metal type (ASTM spec, gauge, coating, alloy/temper, finish)"

− - "ANSI/SPRI ES-1 test report and listing for each roof-edge profile (FM 4435 where required)"

− - "Shop drawings (plan, section, elevation; joints, cleats, expansion joints, hems, corners)"

− - "Fabricator qualifications with project references for metal type and joint methods"

−```

−

−```datasheet

−label: Roof-Edge Metal ES-1 Test Documentation Submittal

−type: radio

−options:

− - "Required — ES-1 listed product (mandatory for all low-slope roof edge per IBC 1504.5)"

− - "Required — ES-1 plus FM 4435 approval (FM Global insured projects)"

− - "Not applicable — sheet metal scope does not include low-slope roof edge"

−default: "Required — ES-1 listed product (mandatory for all low-slope roof edge per IBC 1504.5)"

−```

−

−### The Contractor shall submit the action submittal items listed above for the Designer of Record's review and approval before procuring materials, fabricating, or beginning installation.

−### The roof-edge metal submittal shall include current ANSI/SPRI ES-1 test documentation for the as-specified profile, securement, and substrate; without that documentation the submittal is incomplete and shall not be approved.

−

−## Closeout Submittals {toc}

−

−### The Contractor shall provide the following at substantial completion before the sheet metal work is accepted.

−

−- Manufacturer's written warranty for prefinished coil and panel, covering film integrity, color fade (delta-E units), and chalk per the AAMA 2605 or 2604 finish-warranty schedule

−- Fabricator's written workmanship warranty

−- Touch-up paint, in the specified color, in sealed factory containers — minimum quantity sufficient for documented field touch-up plus owner attic-stock per the contract documents

−- Final marked-up shop drawings showing as-installed expansion-joint locations, all field-cut and field-fitted pieces, and the location of any field repair

−- Maintenance instructions for cleaning, periodic inspection, and sealant joint maintenance, prepared by the fabricator or finish manufacturer

−

−```datasheet

−label: Closeout Submittals Required

−type: checkbox

−options:

− - "Manufacturer's written finish warranty for prefinished coil and panel (film, color fade, chalk)"

− - "Fabricator's written workmanship warranty"

− - "Touch-up paint in specified color, sealed factory containers, plus owner attic-stock"

− - "Final marked-up shop drawings (as-installed expansion joints, field-cut pieces, field repairs)"

− - "Maintenance instructions for cleaning, inspection, and sealant joint maintenance"

−default:

− - "Manufacturer's written finish warranty for prefinished coil and panel (film, color fade, chalk)"

− - "Fabricator's written workmanship warranty"

− - "Touch-up paint in specified color, sealed factory containers, plus owner attic-stock"

− - "Final marked-up shop drawings (as-installed expansion joints, field-cut pieces, field repairs)"

− - "Maintenance instructions for cleaning, inspection, and sealant joint maintenance"

−```

−

−### The Contractor shall provide the closeout submittal items listed above at substantial completion before the sheet metal work is accepted.

−

−# Quality Assurance {toc}

−

−## Fabricator Qualifications {toc}

−

−### The sheet metal fabricator shall have a minimum of five years of documented experience fabricating architectural sheet metal in the metal type, gauge, and finish specified, including shop or field soldering of copper or stainless steel where those metals are required to be soldered.

−### The fabricator shall have brake and roll-forming capacity adequate for the longest piece on the project.

−### The Contractor shall submit the fabricator's project list as part of the qualification documentation.

−

−## Installer Qualifications {toc}

−

−### The installer shall be experienced in architectural sheet metal installation, with documented experience installing ES-1-listed roof-edge metal where that scope is included.

−### The installer shall coordinate directly with the roofing Contractor where the sheet metal scope interfaces with the membrane assembly.

−### On projects carrying a membrane manufacturer's NDL warranty (see [[sync/membrane-roofing]]), edge metal that is integrated with the warranted roofing system shall be installed by an installer authorized by the membrane manufacturer or in a coordination relationship that preserves the warranty.

−

−## Pre-Installation Conference {toc}

−

−### A pre-installation conference shall be held before sheet metal installation begins.

−### Attendees shall include the Contractor's sheet metal installer, the roofing Contractor, the mason or wall-cladding contractor, the Designer of Record, and the Owner's representative.

−### The conference shall cover sequencing with the roofing and wall trades (which membrane base flashings must be in place before counterflashings, which cant strips before coping installation, which through-wall flashings before masonry coursing proceeds), expansion-joint locations, sealant joint design, ES-1 fastener pattern verification, dissimilar-metal isolation, and field cutting and touch-up policy.

−### Minutes shall be distributed within five business days.

−

−## Mock-Up {toc}

−

−### Where the project includes prominent visible sheet metal — exposed copings, fasciae visible from grade, custom gutter profiles, or copper or zinc roofing-adjacent flashings — a field mock-up shall be installed for review before production fabrication.

−### The mock-up shall include at least one corner condition, at least one expansion joint, and at least one termination, and shall be reviewed by the Designer of Record and the Owner before production work proceeds.

−### Approved mock-ups may remain as part of the finished work if they pass inspection.

−

−# Sheet Metal Materials {toc}

−

−## Material Selection — Principles {toc}

−

−### Metal selection is driven by the design service life, the visual exposure of the finished surface, the chemistry of the environment (coastal, industrial, urban), galvanic compatibility with adjacent metals, the substrate to which the metal will be fastened, and budget. {note}

−

−### Galvanic compatibility is a hard constraint, not a preference: copper in contact with aluminum or galvanized steel, water-borne copper salts washing onto aluminum below, or carbon-steel fasteners in contact with stainless or aluminum sheet will all produce galvanic corrosion that progresses for the life of the building. {note}

−### The Designer of Record shall establish the metal type for each piece in the scope.

−

−```datasheet

−label: Predominant Sheet Metal Type

−type: radio

−options:

− - "Prefinished galvanized steel — ASTM A653, G90 coating designation"

− - "Prefinished Galvalume — ASTM A792, AZ50 or AZ55 coating designation"

− - "Aluminum sheet — ASTM B209, alloy 3105-H14 or 5005-H14"

− - "Stainless steel — ASTM A240, Type 304 (interior, mild exterior)"

− - "Stainless steel — ASTM A240, Type 316 (coastal or corrosive)"

− - "Copper — ASTM B370, cold-rolled, 16 oz/sf or 20 oz/sf"

− - "Zinc — ASTM B69, rolled architectural zinc"

−default: "Prefinished galvanized steel — ASTM A653, G90 coating designation"

−```

−### The Contractor shall not substitute a different metal type or coating without written approval and confirmation that the substitution does not create a galvanic incompatibility.

−

−## Galvanized Steel — ASTM A653 {toc}

−

−```datasheet

−label: Galvanized Steel Coating Designation

−type: radio

−options:

− - "G90 (0.90 oz/sf total both sides — minimum for exterior architectural use)"

− - "G60 (not acceptable for exterior; interior or concealed only)"

−default: "G90 (0.90 oz/sf total both sides — minimum for exterior architectural use)"

−```

−

−```datasheet

−label: Galvanized Steel Minimum Gauge — General Trim

−type: select

−unit: gauge (ga)

−options:

− - "26 ga (0.0217 in — light trim only, short spans)"

− - "24 ga (0.0276 in — typical light counterflashing and closure trim)"

− - "22 ga (0.0336 in — typical coping, fascia, and gutter)"

− - "20 ga (0.0396 in — long spans and high-exposure pieces)"

− - "Per SMACNA recommendation for piece type and span"

−default: "Per SMACNA recommendation for piece type and span"

−```

−

−### Hot-dip galvanized sheet steel for architectural flashing and trim shall conform to ASTM A653/A653M, with a minimum G90 coating designation (0.90 oz/sf total both sides, triple-spot test).

−### G60 coating is not appropriate for exterior architectural use and shall not be substituted.

−### The base steel shall be commercial steel (CS) or forming steel (FS) per ASTM A653 as appropriate for the forming complexity.

−### The Contractor shall avoid leaving exposed cut edges in locations where water collects; cathodic protection from the adjacent zinc coating mitigates edge corrosion in service but does not eliminate it.

−### Where bare cut edges are unavoidable, they shall receive a touch-up of cold galvanizing compound (95% zinc, mil-spec compliant) or a compatible primer and finish.

−### Galvanized steel is the most cost-effective metal for exterior sheet metal trim on commercial buildings and is the default for non-prominent flashing scopes when finished with a prepainted PVDF or SMP coil coating; bare mill galvanized weathers from a "spangle" pattern to uniform gray over several years, and a prepainted finish is preferred on prominent surfaces. {note}

−### The Contractor shall follow the SMACNA gauge tables unless the contract documents specify a heavier gauge; a lighter gauge can result in oil-canning, seam distortion, and reduced longevity, while a heavier gauge increases stiffness at the cost of brake-forming difficulty.

−

−## Galvalume (55% Al-Zn) — ASTM A792 {toc}

−

−```datasheet

−label: Galvalume Coating Designation

−type: radio

−options:

− - "AZ50 (standard exterior architectural)"

− - "AZ55 (extended exposure, corrosive environments)"

−default: "AZ50 (standard exterior architectural)"

−```

−

−### Galvalume sheet steel shall conform to ASTM A792/A792M, with AZ50 (0.50 oz/sf total both sides) coating designation for exterior architectural use, or AZ55 for extended-exposure applications.

−### The 55% aluminum-45% zinc coating provides substantially longer service life than G90 galvanized in most exterior environments, but is less effective than galvanized in alkaline contact (mortar runoff, fresh concrete, animal-confinement environments) because the aluminum-rich coating is dissolved by high-pH water. {note}

−### Galvalume is the predominant substrate for prefinished coil used in low-slope roof-adjacent sheet metal and is widely available in PVDF and SMP coil finishes. {note}

−

−## Aluminum — ASTM B209 {toc}

−

−```datasheet

−label: Aluminum Alloy and Temper

−type: radio

−options:

− - "3003-H14 (general-purpose formed sheet)"

− - "3105-H14 (improved corrosion resistance; standard for painted coil)"

− - "5005-H14 (preferred substrate for anodized finish)"

−default: "3105-H14 (improved corrosion resistance; standard for painted coil)"

−```

−

−```datasheet

−label: Aluminum Sheet Minimum Thickness

−type: select

−unit: in

−options:

− - "0.032 in (general flashing and trim)"

− - "0.040 in (light coping and fascia)"

− - "0.050 in (typical coping, long-span fascia, gutter)"

− - "0.063 in (high-exposure coping, large gutter, structural fascia)"

− - "0.080 in (custom long-span coping, ornamental)"

− - "Per SMACNA recommendation for piece type and span"

−default: "Per SMACNA recommendation for piece type and span"

−```

−

−### Aluminum sheet for architectural flashing and trim shall conform to ASTM B209/B209M, using alloy 3105-H14 or 5005-H14 for formed sheet, or 3003-H14 for copings, fasciae, and trim that are not anodized.

−### 5005-H14 is the preferred substrate for anodized finishes; 3105-H14 is general-purpose with good formability.

−### Aluminum shall not be used in direct, continuous contact with mortar or fresh concrete (alkaline attack), nor in direct galvanic contact with copper or copper-bearing salts.

−### Where dissimilar-metal contact is unavoidable, isolation per the Dissimilar Metal Isolation section is required.

−### Aluminum is light, corrosion-resistant in most atmospheric environments, and the standard substrate for prefinished PVDF coil-coated trim on commercial buildings. {note}

−

−## Stainless Steel — ASTM A240 {toc}

−

−```datasheet

−label: Stainless Steel Grade

−type: radio

−options:

− - "Type 304 — interior or mild exterior atmospheric exposure"

− - "Type 316 — coastal, chloride-exposed, or de-icing-salt environments"

−default: "Type 304 — interior or mild exterior atmospheric exposure"

−```

−

−```datasheet

−label: Stainless Steel Surface Finish

−type: radio

−options:

− - "No. 2B — cold-rolled, annealed, smooth, low-reflectivity (general flashing)"

− - "No. 4 — brushed satin (visible architectural)"

− - "No. 8 — mirror polished (specialty visible only; not typical for flashing)"

−default: "No. 2B — cold-rolled, annealed, smooth, low-reflectivity (general flashing)"

−```

−

−```datasheet

−label: Stainless Steel Sheet Minimum Thickness

−type: select

−unit: in

−options:

− - "0.0187 in (26 ga — general light flashing)"

− - "0.0250 in (24 ga — typical counterflashing and trim)"

− - "0.0312 in (22 ga — coping, fascia)"

− - "0.0375 in (20 ga — heavy or long-span work)"

−default: "0.0250 in (24 ga — typical counterflashing and trim)"

−```

−

−### Stainless steel sheet for architectural flashing shall conform to ASTM A240/A240M, with surface finish per ASTM A480/A480M.

−### Type 304 (UNS S30400) is the standard architectural grade for interior and mild exterior environments.

−### Type 316 (UNS S31600), containing molybdenum for improved chloride resistance, shall be specified for coastal environments (within five miles of salt water), de-icing-salt-exposed locations, and pool-area applications.

−### The standard architectural finish shall be No. 2B (cold-rolled, annealed, smooth, low-reflectivity) for general flashing and trim, or No. 4 (brushed, satin) where a directional appearance is desired on visible work.

−### Stainless steel is the most durable common architectural sheet metal in chloride-exposed environments but is the most difficult to form and join — it work-hardens during brake forming, requires larger inside-bend radii to avoid cracking, requires welding rather than soldering in heavier gauges, and is the most expensive common architectural metal. {note}

−

−## Copper — ASTM B370 {toc}

−

−```datasheet

−label: Copper Sheet Weight

−type: radio

−options:

− - "16 oz/sf (0.0216 in — light flashing, short spans)"

− - "20 oz/sf (0.0270 in — typical coping, fascia, gutter; recommended default)"

− - "24 oz/sf (0.0323 in — long-span gutter, ornamental, premium service life)"

−default: "20 oz/sf (0.0270 in — typical coping, fascia, gutter; recommended default)"

−```

−

−```datasheet

−label: Copper Finish at Installation

−type: radio

−options:

− - "Mill (bright) — natural weathering to patina"

− - "Lead-coated copper (architectural lead-tin terne; restricted use under modern lead regulations)"

− - "Pre-patinated (factory-applied chemical patina, accelerated weathering)"

−default: "Mill (bright) — natural weathering to patina"

−```

−

−### Copper sheet for architectural sheet metal shall conform to ASTM B370, cold-rolled and tempered, with weight specified in ounces per square foot (16 oz/sf approximately 0.0216 in, 20 oz/sf 0.0270 in, 24 oz/sf 0.0323 in).

−### The Owner shall be informed of the weathering trajectory before specifying copper for prominent surfaces, since copper weathers from bright copper through brown to a stable patina over years to decades and the patinated surface is itself the corrosion-protection layer.

−### Where copper is installed above a porous surface (limestone, concrete, painted aluminum) that will be visible after weathering, the drip line of the copper shall be detailed to direct water away from the porous surface, or the porous surface shall be protected by an intervening element that takes the staining out of the public view.

−### Copper shall not be installed in direct galvanic contact with aluminum, galvanized steel, zinc, or steel — including via runoff onto those metals from above.

−### Copper joints in pieces likely to be soldered (gutters, scuppers, long-run counterflashings) shall be made with lead-free solder per current building-code requirements.

−### Rosin flux shall be used and shall be neutralized and washed after soldering to prevent corrosion under the solder line.

−### Soldered joints in heavier-weight copper (20 oz/sf and 24 oz/sf) shall be performed by a soldering operator experienced in the heavier weight, because they require more heat input and slower work than 16 oz/sf.

−

−## Zinc — ASTM B69 {toc}

−

−```datasheet

−label: Zinc Sheet Thickness

−type: select

−unit: mm

−options:

− - "0.7 mm (light trim, short runs)"

− - "0.8 mm (typical coping, fascia, gutter)"

− - "1.0 mm (long spans, heavy-exposure)"

−default: "0.8 mm (typical coping, fascia, gutter)"

−```

−

−### Architectural zinc sheet (rolled zinc-copper-titanium alloy) shall conform to ASTM B69, in standard architectural thicknesses of 0.7 mm, 0.8 mm, and 1.0 mm.

−### All zinc sheet metal shall be installed with a ventilated underside per the zinc manufacturer's published details, because zinc has very low tolerance for stagnant moisture on the underside (white corrosion is a rapidly progressing failure mode).

−### Zinc shall not be installed over a moisture-trapping underlayment.

−### Zinc shall not be in direct contact with copper, copper-bearing salts, oak or chestnut tannins, or continuous wet alkaline materials (fresh concrete, mortar).

−### Zinc forms a self-healing carbonate patina in atmospheric exposure that protects the underlying metal and gives architectural zinc its characteristic blue-gray appearance. {note}

−

−# Finishes {toc}

−

−## Prepainted Coil — PVDF and SMP {toc}

−

−```datasheet

−label: Prefinished Coil Coating System

−type: radio

−options:

− - "AAMA 2605 — 70% PVDF (Kynar 500 / Hylar 5000) — premium architectural"

− - "AAMA 2604 — 50% PVDF or SMP-PVDF blend — high-performance general"

− - "AAMA 2603 — commercial polyester — low-exposure or interior only"

−default: "AAMA 2605 — 70% PVDF (Kynar 500 / Hylar 5000) — premium architectural"

−```

−

−```datasheet

−label: Prefinished Coil Color Selection

−type: text

−drawing_ref: "finish schedule"

−default: deferred

−```

−

−### Prefinished coil-coated steel and aluminum sheet for architectural sheet metal trim shall be coated with an AAMA 2605, AAMA 2604, or AAMA 2603 system, selected by the Designer of Record based on service life, visual exposure, and budget.

−### Full-strength 70% PVDF (Kynar 500 / Hylar 5000) systems conforming to AAMA 2605 shall be used for prominent visible exterior architectural metal.

−### 50% PVDF / SMP-PVDF blend systems conforming to AAMA 2604 are appropriate for general commercial trim where the visible exposure is moderate.

−### Commercial polyester (AAMA 2603) shall not be specified for prominent exterior architectural surfaces with long service-life expectations; it is appropriate only for low-exposure, low-visibility, or interior trim.

−### The Contractor shall confirm the coil-coating order requirements and lead time at the time of submittal, because a custom color with an 8-week coil lead time can become the critical path of the sheet metal scope.

−

−## Anodized Aluminum — AAMA 611 {toc}

−

−```datasheet

−label: Anodized Aluminum Class

−type: radio

−options:

− - "AAMA 611 Class I — minimum 0.7 mil coating (exterior architectural)"

− - "AAMA 611 Class II — minimum 0.4 mil coating (interior or low-exposure exterior)"

−default: "AAMA 611 Class I — minimum 0.7 mil coating (exterior architectural)"

−```

−

−### Anodized aluminum finishes shall conform to AAMA 611, using Class I anodizing (minimum 0.7 mil coating thickness) for exterior architectural use and Class II (minimum 0.4 mil) for interior or low-exposure exterior use only.

−### The Contractor shall confirm acceptable color variation tolerance with the Designer of Record before ordering, because anodized finishes are inherently variable in color across coils and lots.

−### The Contractor shall order all anodized aluminum for a single building elevation from a single coil run where uniformity is critical.

−

−## Mill and Natural Finishes {toc}

−

−### Where mill or natural-finish metal is specified, the Designer of Record shall confirm in writing that the Owner has been informed of the visual progression and that the un-weathered initial appearance is acceptable.

−### Once installed, mill-finish metal cannot be made to look like a prepainted finish; substitution after the fact is not feasible. {note}

−

−## Field Touch-Up {toc}

−

−### Field touch-up paint shall match the coil-coating system and color exactly and shall be supplied by the same coating manufacturer as the coil.

−### Touch-up shall be limited to small scratches, cut edges, and fastener heads where the field-applied finish will not be in direct UV exposure (cut edges concealed by the bend, fastener heads beneath a sealant joint).

−### Field-painted patches on visible surfaces shall be avoided because they weather differently than the surrounding factory finish; pieces with visible damage on prominent surfaces shall be replaced, not touched up.

−

−# Accessory Materials {toc}

−

−## Fasteners {toc}

−

−```datasheet

−label: Fastener Material — Galvanized, Galvalume, Aluminum, and Steel Substrate

−type: radio

−options:

− - "Stainless steel Type 304, with EPDM-bonded washer"

− - "Stainless steel Type 316, with EPDM-bonded washer (coastal)"

− - "Hot-dip galvanized steel (ASTM A153) — interior or concealed only"

−default: "Stainless steel Type 304, with EPDM-bonded washer"

−```

−

−```datasheet

−label: Fastener Material — Copper Sheet

−type: radio

−options:

− - "Copper or copper-alloy nails (loose-laid roofing application)"

− - "Stainless steel Type 304 or 316 screws with EPDM-bonded washer"

− - "Brass screws"

−default: "Stainless steel Type 304 or 316 screws with EPDM-bonded washer"

−```

−

−```datasheet

−label: Fastener Material — Zinc Sheet

−type: radio

−options:

− - "Stainless steel Type 304 (interior, mild exterior)"

− - "Stainless steel Type 316 (coastal or chloride-exposed)"

−default: "Stainless steel Type 304 (interior, mild exterior)"

−```

−

−### Fasteners for architectural sheet metal shall be of a metal compatible with the sheet being fastened to avoid galvanic corrosion.

−### Where compatibility cannot be achieved with a fastener of the same metal as the sheet, the fastener material shall be at least as noble as the sheet metal — never less noble.

−### Stainless steel screws with EPDM-bonded washers shall be used to fasten prefinished galvanized, Galvalume, aluminum, and stainless sheet to wood blocking, plywood, or steel substrate.

−### Aluminum fasteners shall be used only with aluminum sheet, and only where the aluminum substrate provides adequate pull-out value.

−### Copper sheet shall be fastened with copper or stainless steel fasteners, never with galvanized or carbon steel fasteners.

−### Zinc sheet shall be fastened with stainless steel fasteners.

−### Exposed fastener heads on visible architectural sheet metal shall be color-matched to the coil finish or covered by a sealant bead and trim.

−### Concealed-fastener attachment (cleats, hooks, and clip systems) is the preferred attachment for prominent visible work because it eliminates the maintenance, leak, and aesthetic concerns of an exposed-fastener field. {note}

−

−## Sealants {toc}

−

−### Sealants for architectural sheet metal joints shall be selected by the type of joint and the expected movement.

−

−```datasheet

−label: Primary Sealant at Sealed Sheet Metal Joints (head and sill flashings, lap joints, terminations)

−type: radio

−options:

− - "Urethane — ASTM C920 Type S, Grade NS, Class 50 (paintable; standard for prefinished coil)"

− - "Silicone — ASTM C920 Type S, Grade NS, Class 50 (highest movement and weathering)"

− - "Butyl tape — closed-cell, non-curing (concealed laps and slip joints only)"

−default: "Urethane — ASTM C920 Type S, Grade NS, Class 50 (paintable; standard for prefinished coil)"

−```

−### Three sealant categories are used: {note}

−

−- **Non-curing butyl tape** (closed-cell butyl conforming to ASTM D1056) is used as a primary water seal at concealed laps and slip joints where the joint is mechanically clamped but is required to be drainable or movable. Butyl tape is the standard sealant beneath cleats, beneath fasteners through hemmed edges, and at the inside of joint covers in expansion joints.

−- **Single-component urethane sealant** conforming to ASTM C920 Type S, Grade NS, Class 50, Use NT, T, M, A, O is appropriate for sealed joints in metal-to-metal applications where the joint is not the primary water barrier (cap-sealing fastener heads, sealing return legs at terminations). Urethane is paintable and color-matched products are available.

−- **Single-component silicone sealant** conforming to ASTM C920 Type S, Grade NS, Class 50 is appropriate for sealed joints where weathering and movement performance govern and where the joint is not in direct contact with substrates incompatible with silicone (silicone shall not be used where it will be painted in service, or in contact with porous substrates where silicone bleed will stain the substrate). For sealant on PVDF-coated surfaces, the silicone manufacturer shall confirm compatibility and provide adhesion test data; many architectural silicones require a primer on PVDF.

−

−### Non-curing butyl tape (closed-cell butyl conforming to ASTM D1056) shall be used as a primary water seal at concealed laps and slip joints, beneath cleats, beneath fasteners through hemmed edges, and at the inside of joint covers in expansion joints.

−### Single-component urethane sealant conforming to ASTM C920 Type S, Grade NS, Class 50, Use NT, T, M, A, O shall be used for sealed metal-to-metal joints that are not the primary water barrier (cap-sealing fastener heads, sealing return legs at terminations).

−### Single-component silicone sealant conforming to ASTM C920 Type S, Grade NS, Class 50 shall be used for sealed joints where weathering and movement performance govern, except where it will be painted in service or in contact with porous substrates that silicone bleed will stain.

−### For sealant on PVDF-coated surfaces, the silicone manufacturer shall confirm compatibility and provide adhesion test data, and shall provide a primer where required.

−

−```datasheet

−label: Sealant Compatibility with PVDF Finish Required (submit adhesion test data)

−type: radio

−options:

− - "Yes — sealant manufacturer to confirm adhesion to specified PVDF finish, primer if required"

− - "Not applicable — sealant not in contact with PVDF surface"

−default: "Yes — sealant manufacturer to confirm adhesion to specified PVDF finish, primer if required"

−```

−

−## Underlayment {toc}

−

−```datasheet

−label: Underlayment Beneath Sheet Metal on Wood Blocking or Wall Sheathing

−type: radio

−options:

− - "Self-adhering polymer-modified bituminous sheet, ASTM D1970, minimum 40 mil"

− - "High-temperature self-adhering bituminous sheet (where metal is dark and surface temperatures exceed 240°F)"

− - "Not required — metal overlies membrane base flashing per roofing detail"

−default: "Self-adhering polymer-modified bituminous sheet, ASTM D1970, minimum 40 mil"

−```

−

−### A self-adhering, polymer-modified bituminous underlayment conforming to ASTM D1970 shall be installed on the substrate beneath all sheet metal flashing surfaces that overlie a structural deck, wall sheathing, or wood blocking.

−### The underlayment shall be lapped a minimum of 4 inches at side laps and 6 inches at end laps, with all laps rolled.

−### Where sheet metal is installed over a membrane roof (gravel stops and copings overlapping the membrane base flashing), a separate underlayment beneath the metal is not required, the cleat or hook strip is fastened through the membrane base flashing into structural blocking, and the membrane manufacturer's published detail governs.

−

−## Cleats and Hook Strips {toc}

−

−```datasheet

−label: Cleat Type — Continuous or Intermittent

−type: radio

−options:

− - "Continuous cleat — full length of piece (preferred for visible work, simplest ES-1 listing)"

− - "Intermittent (clip) cleat — confirmed by ES-1 test for as-built spacing"

−default: "Continuous cleat — full length of piece (preferred for visible work, simplest ES-1 listing)"

−```

−

−### Cleats and hook strips are continuous or intermittent strips of metal fastened to the substrate that engage a hemmed return on the sheet metal piece, securing it against wind uplift without exposed fasteners through the visible face. {note}

−### Cleats shall be of the same metal as the sheet they engage, or a more noble, compatible metal (stainless cleats with stainless or aluminum sheet are common).

−### Cleat gauge shall be at least equal to the sheet gauge, and typically one gauge heavier where the sheet is at the lighter end of the SMACNA-recommended range.

−### Cleat material, gauge, and fastener spacing are integral to the ANSI/SPRI ES-1 wind classification of the assembly. {note}

−### Continuous cleats shall be used in preference to intermittent (clip) cleats for prominent visible work, to distribute engagement uniformly along the hem and eliminate localized hem distortion at clip locations.

−### An intermittent cleat shall not be substituted for a continuous cleat in an ES-1-listed assembly without revised testing; intermittent cleats are acceptable in concealed locations and where the ES-1 test has been performed on the intermittent configuration.

−

−# Fabrication {toc}

−

−## General Principles {toc}

−

−### Sheet metal shall be brake-formed in the shop wherever practicable, with field forming reserved for closures and end conditions that cannot be pre-dimensioned.

−### The maximum shipping length of a single piece shall be coordinated with site access and the brake's capability; longer pieces (24 to 30 ft) reduce the number of field joints but require larger trucks, careful handling, and adequate site staging space.

−### All bends shall be made with the prefinished or painted side outward (where the bend is convex to the finished face) and shall use a brake with sufficient inside-bend radius to avoid cracking the coating.

−### PVDF-coated coil shall be bent to an inside-bend radius of 1 to 1.5 times the metal thickness or greater without coating fracture; tighter bends require radiused brake dies and a slow press cycle.

−### Cracked coatings at the apex of a bend are a finish failure that cannot be touched up and shall result in rejection of the piece.

−### Cut edges shall be deburred and shall not be left sharp or with visible feathers.

−### Edges that will be exposed in service (the open end of a hem, the lower edge of a gravel stop, the upper edge of an uncapped counterflashing) shall be hemmed back on themselves so that no raw edge is exposed.

−

−## Joints {toc}

−

−### Three primary joint types are used in architectural sheet metal: lapped joints sealed with butyl tape or sealant, standing seams (folded and hemmed double-lock seams in long-run pieces), and slip-and-lock joints with backer plates at expansion joints. {note}

−

−### The joint type for each piece shall be specified on the shop drawings and shall match the SMACNA detail being followed.

−

−```datasheet

−label: Coping and Fascia Field Joinery

−type: radio

−options:

− - "Double-lock standing seam — preferred for visible work"

− - "Slip-and-lock with backer plate at expansion joints, double-lock between"

− - "Lapped with butyl and sealant — short-run or concealed work"

−default: "Slip-and-lock with backer plate at expansion joints, double-lock between"

−```

−### Lapped joints with sealant shall have a minimum lap of 2 inches in the direction of water flow, with a continuous butyl tape concealed within the lap and a continuous bead of sealant tooled to a clean fillet at the upstream edge of the lap.

−### Standing seams shall be a minimum 1 inch tall, hand-sealed or machine-seamed where the machine is appropriate to the gauge and metal, and double-lock seams shall be used in preference to single-lock for permanent installations.

−### Slip-and-lock expansion joints (S-locks) shall consist of a backer plate of matching profile lapped into the running joint with butyl tape and a clamping cover or hemmed return that allows the running pieces to slide axially as thermal movement occurs.

−### The slip-and-lock joint shall be sealed on the upstream side with butyl tape only; sealant shall not bridge the moving portion of the joint, because sealant bridges that constrain movement will be torn open by the first significant thermal cycle.

−

−## Cleats {toc}

−

−### Cleats shall be fabricated of the same metal type as the sheet they secure, and a gauge equal to or one heavier than the sheet.

−### Continuous cleats shall be installed in lengths matching the cleated piece, with adjacent cleat sections butted (not lapped) and the joint located so that it does not coincide with a sheet metal joint.

−### Cleat fastener spacing shall match the ANSI/SPRI ES-1 listing for the assembly, and the listed spacing shall be marked on the shop drawings and verified in the field.

−### Intermittent cleats, where used, shall be a minimum 2 inches wide and shall be spaced at a maximum of 12 inches on center, or closer per the ES-1 listing.

−### The intermittent cleat shall be of the same metal as the sheet and shall be set in butyl tape between the cleat and the substrate.

−

−## Hems {toc}

−

−```datasheet

−label: Standard Edge Hem

−type: radio

−options:

− - "Single hem — 1/2 in fold-back (typical concealed edges)"

− - "Double hem — folded twice (long-span exposed edges, gutter rim)"

− - "Open hem with closure — open hem with a separate closure strip"

−default: "Single hem — 1/2 in fold-back (typical concealed edges)"

−```

−

−### The standard architectural hem shall be a 1/2-inch single hem, formed by bending the sheet 180 degrees back on itself.

−### Double hems (folded twice) shall be used at long-span edges (gutter outer faces, long fascia bottoms) for additional stiffness.

−### Drip hems on the lower edges of gravel stops, fasciae, and drip edges shall extend at least 1/2 inch out from the substrate face and shall be turned downward at least 30 degrees from horizontal so that water drips clear of the substrate face rather than wicking back along the metal underside.

−

−## Expansion Joint Provisions {toc}

−

−### The expansion joint spacing in running sheet metal shall be designed for the metal's coefficient of thermal expansion and the expected temperature range.

−

−```datasheet

−label: Maximum Spacing Between Expansion Joints — Prefinished Steel and Galvalume

−type: select

−unit: ft

−options:

− - "30 ft (conservative; dark colors, high-temperature climates)"

− - "40 ft (typical for medium-color prefinished coil in temperate climates)"

− - "Per SMACNA Architectural Sheet Metal Manual table for project climate and color"

−default: "Per SMACNA Architectural Sheet Metal Manual table for project climate and color"

−```

−

−```datasheet

−label: Maximum Spacing Between Expansion Joints — Prefinished Aluminum

−type: select

−unit: ft

−options:

− - "20 ft (dark colors, high-temperature climates)"

− - "25 ft (typical for medium-color prefinished aluminum)"

− - "Per SMACNA Architectural Sheet Metal Manual table for project climate and color"

−default: "Per SMACNA Architectural Sheet Metal Manual table for project climate and color"

−```

−### Approximate maximum running lengths between expansion joints, for prefinished coil exposed to direct sun on a low-slope roof in temperate climates, are: {note}

−

−- Prefinished galvanized or Galvalume steel: approximately 40 ft maximum between expansion joints (coefficient of thermal expansion approximately 7 x 10^-6 in/in/°F)

−- Prefinished aluminum: approximately 25 ft maximum between expansion joints (coefficient of thermal expansion approximately 13 x 10^-6 in/in/°F)

−- Copper: approximately 30 ft maximum between expansion joints

−- Stainless steel: approximately 40 ft maximum between expansion joints

−- Zinc: approximately 25 ft maximum between expansion joints

−

−### Failure to accommodate thermal movement results in buckling in hot weather, joint tearing in cold weather, and fastener pull-through over many thermal cycles. {note}

−### The SMACNA Architectural Sheet Metal Manual provides specific tables keyed to climate zone and surface color, since darker surfaces reach higher peak temperatures and require closer joint spacing. {note}

−### The Designer of Record shall confirm the joint spacing on the contract documents, and the Contractor shall locate joints [[drawing: as indicated on the elevations]] consistent with the SMACNA-recommended maximum for the metal and climate.

−### Each expansion joint shall be a slip-and-lock joint with backer plate and butyl tape.

−### Expansion joints shall not be located at corners; corners shall be solidly joined (lapped, soldered, or double-lock-seamed) and the expansion joint shall be located in the running section at least 18 inches from the corner so that the corner does not absorb the entirety of the thermal movement.

−

−## Soldering and Welding {toc}

−

−### Soldering of copper and lead-coated copper joints shall use lead-free solder per current code requirements, with rosin flux applied, the joint heated to flow temperature with a soldering iron or torch sized for the metal weight, solder drawn into the joint by capillary action, and the joint cleaned of flux residue after cooling.

−### Soldered joints shall be inspected for full solder penetration, and voids in soldered seams shall be re-soldered.

−### Soldering of copper greater than 16 oz/sf shall use larger soldering irons (typically electric or fuel-fired) and a slower work pace than 16 oz/sf.

−### Stainless steel joints in pieces too heavy to solder, or where solder appearance is undesirable, shall be welded by a qualified welder using TIG or MIG welding appropriate to the gauge.

−### Heat input shall be controlled to minimize distortion and to limit the affected zone where the welded zone may corrode preferentially (sensitization).

−### Welded stainless joints in visible work shall be ground, polished, and passivated to restore corrosion resistance and a uniform appearance.

−### Galvanized steel and aluminum joints shall not be soldered or welded; joints in galvanized and aluminum sheet shall be formed by mechanical seams (lapped with sealant, standing seams, slip-and-lock) as described in the Joints section.

−

−# Roof Edge Securement — ANSI/SPRI ES-1 {toc}

−

−## Compliance Requirement {toc}

−

−```datasheet

−label: Edge-Zone Design Wind Pressure (per ASCE 7 components-and-cladding)

−type: range

−unit: psf

−drawing_ref: true

−options:

− min: 30

− max: 200

− setpoints: [30, 45, 60, 75, 90, 105, 120, 150, 200]

−default: 75

−```

−

−```datasheet

−label: ES-1 Compliance Path for Roof-Edge Metal

−type: radio

−options:

− - "ES-1-listed manufactured product — listing meets or exceeds design edge pressure"

− - "Field-fabricated profile tested per ES-1 for the project as-built configuration"

− - "Engineered design by licensed engineer demonstrating equivalent wind resistance"

−default: "ES-1-listed manufactured product — listing meets or exceeds design edge pressure"

−```

−

−### ANSI/SPRI/FM 4435/ES-1 establishes the wind-pressure resistance of metal edge systems used on low-slope roofs and defines three test methods: RE-1 (horizontal displacement after wind pressure), RE-2 (vertical pull-out under wind uplift), and RE-3 (cyclic pressure simulating fluctuating wind). {note}

−### IBC Section 1504.5 requires that all metal-edge cover assemblies on low-slope roofs be designed, tested, and labeled in accordance with ES-1 for the wind pressure at the building's perimeter and corner zones, calculated per ASCE 7 components-and-cladding provisions.

−### Field-fabricated edge metal (coping, gravel stop, fascia) is not ES-1-listed unless the as-fabricated profile and securement match a tested configuration of the cleat, fastener spacing, hem return, and substrate. {note}

−### The Contractor shall not field-fabricate roof-edge metal on a low-slope roof and treat it as code-compliant; either an ES-1-listed manufactured product shall be specified, the field-fabricated profile shall be engineered and tested for the project, or the design shall be by a licensed engineer whose calculation demonstrates compliance with the underlying wind-resistance requirement.

−

−## Cleat and Fastener Pattern {toc}

−

−### For ES-1-listed edge-metal assemblies, the cleat material, gauge, fastener type, fastener spacing, and substrate are integral to the listing, and substituting any component voids the listing for that section of the roof edge.

−### The Contractor shall verify in the field that the installed nailer dimensions and the cleat fastener pattern match the ES-1 listing documents in the submittal package; deviation shall be reported to the Designer of Record and corrected before the edge metal is installed.

−### Continuous wood nailers supporting the cleat and cover shall be pressure-treated for exterior exposure (typically alkaline copper quaternary or copper azole preservative compatible with the cleat and fastener metals), and preservatives that release chloride or that are highly acidic shall be avoided where they contact aluminum or zinc-coated steel.

−### Nailer attachment to the structure (number, type, spacing of fasteners into the deck or parapet wall) is part of the ES-1-tested assembly and shall not be altered.

−

−# Counterflashing and Wall Flashing {toc}

−

−## Counterflashings at Membrane Roof Base Flashings {toc}

−

−```datasheet

−label: Counterflashing Termination at Wall

−type: radio

−options:

− - "Reglet — continuous saw-cut groove in concrete or masonry, counterflashing wedged or lead-caulked into reglet"

− - "Manufactured masonry receiver — installed during masonry work, counterflashing engaged at top"

− - "Below through-wall flashing — counterflashing terminates beneath a separate through-wall flashing"

− - "Surface-mounted — counterflashing fastened to wall face, top edge sealed (retrofit only)"

−default: "Manufactured masonry receiver — installed during masonry work, counterflashing engaged at top"

−```

−

−```datasheet

−label: Counterflashing Lap Over Membrane Base Flashing (minimum)

−type: select

−unit: in

−options:

− - "3 in"

− - "4 in"

− - "6 in"

−default: "4 in"

−```

−

−### Counterflashings protect the top termination of the membrane base flashing from UV, debris, and physical damage; the membrane base flashing remains the primary water barrier, and the counterflashing is a secondary, mechanically removable protection for future re-roofing. {note}

−### Counterflashings shall be installed in a reglet in the wall (a continuous saw-cut groove or a manufactured masonry receiver) or under a through-wall flashing in masonry construction.

−### Surface-mounted counterflashings (fastened to the wall face with exposed fasteners and a top-edge sealant joint) are acceptable only on retrofits where reglet cutting is not feasible, and require periodic sealant replacement because they depend on the sealant joint for water exclusion.

−### The counterflashing shall lap over the top of the membrane base flashing by a minimum of 4 inches.

−### The lap zone shall not be sealed (counterflashings are removable for future re-roofing), but the lap geometry shall shed water down the face of the base flashing rather than directing it behind the base flashing.

−### Counterflashings shall be designed so that any water entering between the counterflashing and the base flashing exits at the bottom of the base flashing onto the roof membrane.

−

−## Through-Wall Flashings at Masonry {toc}

−

−### Through-wall flashings shall be installed within masonry walls at the base of the wall, at floor lines, at heads and sills of openings, and at shelf angles, to intercept water that has penetrated the outer wythe and direct it back out at the wall face through weep openings.

−### The exposed drip-edge portion of a through-wall flashing that projects from the wall face shall be sheet metal (typically stainless steel or copper) lapped under or hemmed with the membrane through-wall flashing within the wall.

−### The through-wall flashing assembly shall be coordinated with the masonry and exterior-wall standards.

−### The exposed metal drip-edge of a through-wall flashing shall project at least 1/4 inch out from the wall face and shall be hemmed downward at a minimum 30-degree angle so that water drips clear of the wall face.

−### Where the projection conflicts with the architectural face of the wall, the through-wall flashing shall be flush with the wall face but the membrane portion above shall extend outward to form a drip in front of the wall face, not behind.

−

−## Head and Sill Flashings {toc}

−

−```datasheet

−label: Head and Sill Flashing Material

−type: radio

−options:

− - "Prefinished galvanized or Galvalume steel, AAMA 2604 or 2605 coating"

− - "Prefinished aluminum, AAMA 2604 or 2605 coating"

− - "Stainless steel — Type 304 or 316 (premium and coastal applications)"

− - "Self-adhering membrane flashing (substitute for sheet metal head and sill flashings on residential or light commercial work)"

−default: "Prefinished aluminum, AAMA 2604 or 2605 coating"

−```

−

−```datasheet

−label: Head Flashing End Dam Required

−type: radio

−options:

− - "Yes — turned-up end tab on each end, minimum 1 in tall, sealed to head flashing back leg"

− - "No (not acceptable for exterior wall openings)"

−default: "Yes — turned-up end tab on each end, minimum 1 in tall, sealed to head flashing back leg"

−```

−

−### Head flashings over wall openings (windows, doors, louvers) shall be continuous formed metal pieces that lap over the top of the frame and turn up at the back behind the wall water-resistive barrier (WRB) so that water on the WRB is directed over the head flashing and out beyond the frame.

−### The head flashing shall extend at least 2 inches beyond each side of the rough opening, with end dams formed on each end (a turned-up tab folded against the back leg) to direct water out the front of the flashing rather than over the side.

−### Sill (pan) flashings below window openings shall be continuous below the window rough sill, lapped over the WRB below and turned up at the front and each side to form a pan that contains any water entering the rough opening and directs it back outward beneath the window.

−### Pan flashings shall be installed before the window unit is set; pan flashings retrofitted after the window is set are not effective.

−

−# Gutters and Downspouts {toc}

−

−## Gutter Design Basis {toc}

−

−```datasheet

−label: Gutter Material

−type: radio

−options:

− - "Prefinished galvanized or Galvalume steel, AAMA 2604 or 2605 coating, minimum 24 ga"

− - "Prefinished aluminum, AAMA 2604 or 2605 coating, minimum 0.050 in (18 ga equivalent)"

− - "Copper, ASTM B370, minimum 20 oz/sf"

− - "Stainless steel, Type 304 or 316, minimum 24 ga"

−default: "Prefinished aluminum, AAMA 2604 or 2605 coating, minimum 0.050 in (18 ga equivalent)"

−```

−

−```datasheet

−label: Gutter Minimum Slope to Downspout

−type: radio

−unit: in per ft

−options:

− - "1/16 in per ft (minimum)"

− - "1/8 in per ft (preferred)"

− - "1/4 in per ft (short runs only; visible slope on long runs)"

−default: "1/8 in per ft (preferred)"

−```

−

−```datasheet

−label: Gutter Cross-Section Sizing Basis

−type: text

−drawing_ref: "civil and roof drawings"

−default: deferred

−```

−

−### Gutter sizing (cross-sectional area, front and back heights, downspout outlet size and spacing) is the responsibility of the Designer of Record, established by a roof drainage calculation based on the contributory roof area, the design rainfall intensity (typically the 100-year, 5-minute storm for primary drainage per IBC Section 1611 or local code), and the gutter slope.

−### The gutter cross-section shall be confirmed against the calculated flow before fabrication.

−### The gutter shall be sloped to downspout outlets at a minimum of 1/16 inch per foot, with 1/8 inch per foot preferred where the gutter length and parapet height allow.

−### Level gutters shall not be specified, because they do not drain reliably (small construction tolerances result in localized low spots and ponding).

−### Gutter expansion joints shall be located at maximum 40-ft spacing for steel and stainless and 25-ft spacing for aluminum; for very long buildings, multiple downspout outlets and intermediate expansion joints shall be coordinated [[drawing: as shown on the elevations]].

−

−## Gutter Joinery {toc}

−

−### Gutter joints shall be soldered (copper, lead-coated copper, terne-coated stainless) or formed with a slip-and-lock backer-plate expansion joint (aluminum, steel, Galvalume, stainless) at intervals not exceeding the metal's maximum running length between expansion joints.

−### Aluminum and steel gutters that cannot be soldered shall be detailed to depend on butyl tape and sealant at lapped joints.

−### Lapped-and-sealed gutter joints shall be in the direction of flow (upstream piece outside, downstream piece inside), a minimum 1 inch lap, with butyl tape concealed within the lap and a tooled sealant bead at the upstream edge.

−### End caps on gutters shall be of the same metal, formed to match the gutter profile, and joined with the gutter by soldering (copper, stainless) or by a sealed lap (aluminum, steel).

−

−## Gutter Hangers and Brackets {toc}

−

−```datasheet

−label: Gutter Hanger Spacing (maximum)

−type: select

−unit: in on center

−options:

− - "24 in o.c. (copper and high-snow-load applications)"

− - "32 in o.c. (typical aluminum and steel)"

− - "36 in o.c. (light gauge gutters in low-snow climates)"

−default: "32 in o.c. (typical aluminum and steel)"

−```

−

−### Gutters shall be supported by hangers or brackets at maximum 32-inch spacing for steel and aluminum and at 24-inch spacing for copper (which is heavier and softer).

−### Hangers shall be of a metal compatible with the gutter; stainless hangers are universal.

−### Hangers shall be designed to support the weight of the gutter filled with water plus a snow and ice load where applicable, because ice-loaded gutters in cold climates can weigh several times the empty gutter weight.

−### Hangers shall not penetrate the inside or bottom of the gutter (puncturing the water-bearing pan); hangers shall be of a type that engages the outer rim of the gutter from above (hidden hangers, strap hangers over the gutter outer rim) so that water in the gutter does not encounter a fastener penetration.

−

−## Downspouts and Conductor Heads {toc}

−

−```datasheet

−label: Downspout Size

−type: radio

−options:

− - "3 in x 4 in rectangular (typical commercial)"

− - "4 in x 5 in rectangular (larger contributory area)"

− - "4 in diameter round"

− - "5 in diameter round"

− - "6 in diameter round (large contributory area or industrial)"

− - "Per Designer of Record roof drainage calculation"

−drawing_ref: true

−default: "Per Designer of Record roof drainage calculation"

−```

−

−```datasheet

−label: Downspout Strap Spacing (maximum)

−type: select

−unit: ft on center

−options:

− - "6 ft o.c."

− - "10 ft o.c."

− - "12 ft o.c."

−default: "10 ft o.c."

−```

−

−### Downspouts shall be sized per the roof drainage calculation and shall be a minimum 3 inches by 4 inches (rectangular) or 4-inch diameter (round) on commercial buildings.

−### Downspout joints shall be lapped in the direction of flow (upper piece outside, lower piece inside) by a minimum of 1 inch, and shall be sealed only at the upper edge of the lap with sealant or soldered.

−### Downspouts shall be anchored to the wall at maximum 10-ft spacing using straps of the same metal as the downspout.

−### Downspouts shall discharge to a tied-in storm-drain inlet, a splash block, or a daylight outlet, whichever is specified on the civil drawings, and shall not discharge to a horizontal grade-level surface without a splash block or routing.

−### Downspout discharge shall be coordinated with [[sync/below-grade-waterproofing]] foundation drainage at any below-grade outlet condition.

−### Conductor heads (collection boxes set at the top of a downspout to receive water from a scupper or short transition piece) shall be sized to hold the design flow without overflow, formed of the same metal as the downspout, and provided with an overflow lip on the open face that directs overflow water outward rather than back against the wall.

−

−# Coping {toc}

−

−## Function and Design Basis {toc}

−

−```datasheet

−label: Coping Cap Material

−type: radio

−options:

− - "Prefinished aluminum, minimum 0.050 in (18 ga equivalent), AAMA 2605 PVDF"

− - "Prefinished galvanized or Galvalume steel, minimum 24 ga (G90 / AZ50), AAMA 2605 PVDF"

− - "Stainless steel, Type 304 or 316, minimum 24 ga (coastal and corrosive environments)"

− - "Copper, minimum 20 oz/sf (historic and premium projects)"

− - "Zinc, minimum 0.8 mm (premium projects)"

−default: "Prefinished aluminum, minimum 0.050 in (18 ga equivalent), AAMA 2605 PVDF"

−```

−

−```datasheet

−label: Coping Slope (transverse to wall)

−type: radio

−unit: in per ft

−options:

− - "1/4 in per ft to inside (toward roof) — preferred"

− - "1/4 in per ft to outside (away from building) — only where roof side is unprotected"

− - "Bidirectional (peaked center) — not preferred; creates two drip lines, two edge issues"

−default: "1/4 in per ft to inside (toward roof) — preferred"

−```

−

−### Coping caps the top of a parapet wall, protecting both the wall construction and the inside-face membrane base-flashing termination from water infiltration from above. {note}

−### Coping is a roof-edge component subject to ANSI/SPRI ES-1; copings shall be ES-1-listed (or engineered-equivalent) for the design wind pressure at the parapet edge zone, which is consistently higher than the field-zone pressure.

−### The coping cap shall be wider than the parapet wall by enough on each side to provide a drip edge clear of the parapet face — typically a minimum 1-1/2 inch overhang on the outside face and 1 inch on the inside face, with both edges hemmed and turned downward to drip away from the parapet face.

−### Coping shall slope from one side to the other (typically toward the roof side) at a minimum of 1/4 inch per foot, achieved by tapering the parapet top or by setting the coping on tapered shim strips.

−### The slope direction shall be toward the roof side so that water leaving the coping falls onto the membrane rather than onto the wall face, which over time accumulates staining and increases wall water-intrusion risk.

−

−## Coping Joinery and Expansion {toc}

−

−```datasheet

−label: Coping Field Joint Type Between Expansion Joints

−type: radio

−options:

− - "Double-lock standing seam (preferred for visible work)"

− - "Lapped with butyl tape and sealant (downstream lap inside)"

−default: "Double-lock standing seam (preferred for visible work)"

−```

−

−### Coping shall be jointed at maximum spacing per the metal's expansion-joint table (typically 40 ft for steel/Galvalume and stainless, 25 ft for aluminum, 30 ft for copper) using slip-and-lock backer-plate joints with butyl tape.

−### Between expansion joints, coping pieces shall be joined by double-lock standing seams or by lapped-and-sealed joints, with lapped joints in the direction of slope so that water sheds over the joint, not under.

−### Corners shall be solidly joined with mitered or soldered corners; expansion joints shall not be located at corners.

−### The cleat or continuous hook strip that engages the coping cap shall be ES-1-listed with the coping cap as an assembly.

−### The cleat shall be fastened to the parapet top through a continuous pressure-treated wood nailer at the spacing required by the ES-1 listing.

−### Coping cleats shall be fastened through butyl tape to seal the fastener penetrations against water infiltration past the cleat.

−

−# Wall Expansion Joints and Expansion Joint Covers {toc}

−

−## Building expansion joints — joints that allow the structural framing on either side to move independently — penetrate the building envelope at the wall and roof. {note}

−

−## The exterior face of the wall expansion joint shall be covered by a flexible expansion-joint cover that accommodates the design movement (typically plus-or-minus 25 to 50 percent of the joint width) and seals the joint against weather.

−

−```datasheet

−label: Wall Expansion Joint Cover Type

−type: radio

−options:

− - "Proprietary engineered expansion-joint cover assembly (preformed bellows + metal trim)"

− - "Site-fabricated sheet metal cover with elastomeric bellows beneath"

− - "Composite metal-and-membrane expansion-joint cover"

−drawing_ref: true

−default: "Proprietary engineered expansion-joint cover assembly (preformed bellows + metal trim)"

−```

−

−```datasheet

−label: Design Movement at Wall Expansion Joint

−type: text

−drawing_ref: "structural drawings"

−default: deferred

−```

−## The sheet metal trim portion of the expansion-joint cover shall be of the metal type matching adjacent flashing and shall be lapped or sealed to the adjacent flashing or wall membrane so that water at the wall membrane plane is directed past the expansion joint without entering it.

−## At the wall-to-roof transition, the expansion-joint cover shall transition continuously from the wall plane onto the roof plane without interruption, because a discontinuous expansion-joint cover at the wall-roof transition is a common leak source.

−

−# Dissimilar Metal Isolation {toc}

−

−## Galvanic Compatibility {toc}

−

−```datasheet

−label: Dissimilar Metal Isolation Method

−type: radio

−options:

− - "EPDM gasket — minimum 1/16 in thick, full-coverage between dissimilar metals"

− - "Butyl tape — non-curing closed-cell, full-coverage"

− - "Polyethylene sheet — minimum 6 mil, full-coverage"

− - "Bituminous paint coat on more noble metal at contact"

− - "Not applicable — no dissimilar metal contact in this scope"

−default: "EPDM gasket — minimum 1/16 in thick, full-coverage between dissimilar metals"

−```

−

−### Galvanic isolation shall be provided wherever metals at significantly different points in the galvanic series are in direct contact, in water-coupled proximity (water from one metal running onto another), or in shared-fastener contact.

−### Isolation shall be achieved by separating the metals with a polymer barrier (EPDM gasket, butyl tape, polyethylene sheet), by coating the more noble metal with a barrier coat where it contacts the less noble, or by using a fastener at least as noble as the more noble metal.

−### In the architectural galvanic series — from most anodic (sacrificed first) to most cathodic (protected): zinc, aluminum, galvanized steel, mild steel, copper alloys, stainless steel — aluminum, zinc, and galvanized steel are most commonly corroded, and copper and stainless most commonly drive corrosion of others. {note}

−

−## Specific Contact Conditions {toc}

−

−### Copper sheet shall not be installed above unprotected aluminum, galvanized steel, or zinc, including via water runoff that washes copper salts onto the metal below.

−### Where copper is installed above metal of a lower nobility, the metal below shall be protected by a non-reactive barrier (for example, a continuous EPDM sheet between the copper and the metal below).

−### Lead-coated copper, terne-coated stainless, and other historic combinations shall have their specific compatibility requirements confirmed with the metal manufacturers before specification.

−### Aluminum sheet shall not be in direct contact with fresh mortar, fresh concrete, or pressure-treated lumber containing copper-based preservatives (alkaline copper quaternary, copper azole) without a barrier coat or polymer separation.

−### Isolation between an aluminum cleat and an ACQ-treated wood nailer is required, because ACQ lumber is acidic and contains soluble copper, both of which attack aluminum.

−### Galvanized steel and zinc sheet shall not be in direct contact with fresh mortar or concrete or in direct copper contact, by which they are degraded.

−### Stainless fasteners through aluminum, galvanized, or zinc sheet shall use EPDM washers to seal the fastener penetration and reduce moisture coupling, even though the small fastener-to-sheet area ratio generally limits corrosion to acceptable levels.

−

−# Installation Sequence {toc}

−

−## Coordination with the Roofing Trade {toc}

−

−### The sheet metal scope is interleaved with the roofing scope at every roof-to-wall, roof-to-curb, and roof-edge interface. {note}

−### The sequencing of which trade installs which component first is fixed by the function of each piece and shall not be altered:

−

−- Wood nailers and blocking at the roof edge and on top of parapets shall be in place before the roofing membrane is installed. The roofing Contractor uses these nailers to terminate the membrane field and base flashings, and the sheet metal Contractor uses them to anchor cleats and edge metal.

−- The roofing Contractor installs the membrane field, the membrane base flashings up the parapet inside face, and any membrane-bonded edge components that are integral to the roofing manufacturer's warranty. Where the edge-metal assembly is supplied as part of the roofing manufacturer's warranted package, the roofing Contractor installs that edge metal.

−- After the membrane base flashings are complete and probed, the sheet metal Contractor installs counterflashings over the top of the base flashings, copings on top of the parapet, and gravel stops or fascias at unparapeted edges.

−- Wall flashings, gutters, downspouts, and trim are installed in coordination with the wall-cladding and rough-carpentry trades, sequenced so that flashings are in place before the wall cladding laps over them.

−

−### The sequencing of which trade installs which component first is fixed by the function of each piece and shall not be altered from the order listed above.

−### The pre-installation conference shall finalize the sequencing for the specific project, with attention to areas where the typical sequence may be altered (for example, where a coping is integrated with a unitized rainscreen panel system and installed as part of the panel scope rather than the sheet metal scope).

−

−## Substrate Acceptance {toc}

−

−### The sheet metal installer shall inspect all substrates before installation and shall not proceed until wood nailers are properly fastened, of the specified thickness and treatment, at the correct elevation and width; membrane base flashings are fully bonded and probed where they will be lapped by counterflashings or copings; masonry is at the correct dimension with clean reglet cuts to the specified depth; and structural framing supporting heavy pieces (gutters, conductor heads) is in place at the correct elevation.

−### Deficient substrates shall be reported to the General Contractor in writing, and the sheet metal Contractor shall not proceed over a non-conforming substrate without correction.

−

−## Field Cutting and Fitting {toc}

−

−### Where field cutting is unavoidable (at end conditions, around penetrations, at irregular corners), cuts shall be made with snips, hand shears, or a powered nibbler appropriate to the metal.

−### Abrasive cutting wheels and grinders shall not be used on prefinished coil-coated sheet, because the heat and abrasive damage the coating along the cut edge and produce a non-touchable edge condition; powered shears or nibblers that do not heat the metal are required.

−### Cut edges shall be deburred and shall receive touch-up paint per the Field Touch-Up section.

−

−# Finishes and Touch-Up {toc}

−

−## Storage and Handling {toc}

−

−### Prefinished coil and panel shall be stored on edge, off the ground, under protective wrap or cover, in a dry location, because coil-coated panels stored flat with weight on top develop oil-canning, dimpling, and finish damage along the contact lines.

−### Panels and pieces shall be protected from moisture during storage, because water trapped between panels causes white-rust on Galvalume and aluminum and surface staining on prefinished coil that may not be removable.

−### Protective films applied at the coil-coating mill shall be left in place during fabrication and installation, and shall be removed only at substantial completion and before any UV exposure that would bond the film to the finish (typical maximum film exposure time is 90 days; the Contractor shall confirm with the coil manufacturer).

−

−## Cleaning {toc}

−

−### Installed sheet metal shall be cleaned at substantial completion of all installation debris, sealant smears, mortar residue, and protective film.

−### Cleaning shall use water and a mild detergent (pH between 5 and 9), applied with a soft cloth or sponge and rinsed clean with potable water.

−### Solvents, acid cleaners, abrasive cleaners, and steel-wool or scratch-pad scrubbers shall not be used on prefinished coil, because these damage the finish.

−### Mortar smears shall be removed promptly (within minutes of contact, before the mortar cures) with water; cured mortar shall be removed by mechanical scraping with a soft plastic or wood scraper, never by acid wash.

−

−## Touch-Up {toc}

−

−### Touch-up paint matching the coil finish shall be applied to all field-cut edges, exposed fastener heads, and minor scratches not exceeding 1/4 inch in any dimension.

−### Larger scratches, dents, or finish damage shall not be touched up on visible surfaces; pieces with significant damage shall be replaced.

−### Touch-up paint shall be allowed to dry per the manufacturer's instructions before the area is subject to water contact or further work.

−

−# Cleaning and Acceptance {toc}

−

−## The sheet metal installation shall be jointly inspected at substantial completion by the Contractor, the Designer of Record, and the Owner's representative.

−## The inspection shall verify that all pieces are in their final position; that joints are properly formed and sealed; that all expansion joints are functional (no sealant bridges across moving portions); that ES-1-listed roof-edge metal is installed per the listed assembly with the correct cleat, fastener type, and spacing; that all flashings overlap correctly and shed water in the design direction; that gutters are sloped and unobstructed; that downspouts are anchored and discharge correctly; that dissimilar-metal isolation is in place where required; and that finished surfaces are clean and free of damage.

−## Deficiencies identified at substantial completion shall be corrected before the Contractor's warranty period begins.

−

−# Warranty {toc}

−

−## Fabricator and Installer Warranty {toc}

−

−```datasheet

−label: Contractor Sheet Metal Workmanship Warranty Period (minimum)

−type: select

−unit: years

−options:

− - "1 year"

− - "2 years"

− - "5 years"

−default: "2 years"

−```

−

−### The Contractor shall provide a written workmanship warranty for the installed sheet metal for a minimum of two years from the date of substantial completion.

−### The warranty shall cover defects in fabrication, joinery, and installation, including leaks at sheet metal joints and detachment under design wind loads.

−### The Contractor's warranty is in addition to the finish manufacturer's warranty and does not substitute for it.

−

−## Finish Manufacturer Warranty {toc}

−

−```datasheet

−label: Prefinished Coil Finish Warranty Term (minimum)

−type: select

−unit: years

−options:

− - "20 years (AAMA 2604 finishes)"

− - "30 years (AAMA 2605 PVDF finishes)"

− - "40 years (premium PVDF systems)"

−default: "30 years (AAMA 2605 PVDF finishes)"

−```

−

−### The prefinished coil manufacturer shall provide a written warranty against finish film integrity, color fade, and chalk per the AAMA 2605 or 2604 schedule for the specified finish.

−### Typical PVDF (AAMA 2605) warranties are 30 years against film failure, 30 years against chalk (with a quantitative limit on chalk rating), and 30 years against color fade (with a quantitative limit on delta-E change); 50% PVDF / SMP (AAMA 2604) warranties are typically 20 years for similar metrics. {note}

−### Project conditions that match any finish-warranty exclusion (heavy industrial fallout, marine spray within 1,500 ft of salt water, agricultural ammonia exposure, chemical exposure, physical impact, or substrates outside the manufacturer's approved substrate list) shall be identified before submittal so that the finish system can be confirmed appropriate for the exposure.

−### The Contractor shall submit the finish manufacturer's warranty form with the submittals.

−

−## Roof-Edge Assembly Warranty {toc}

−

−### Where the roof-edge metal is supplied as part of the membrane roofing manufacturer's NDL warranty package (see [[sync/membrane-roofing]]), the roof-edge metal is covered by the membrane warranty under the same terms as the membrane.

−### Where the roof-edge metal is supplied by an independent edge-metal manufacturer with its own warranty, the Contractor shall obtain that warranty separately and submit it at closeout.

−### Coordination between the membrane warranty and the edge-metal warranty shall be confirmed before the edge-metal product is selected, because an edge-metal product not on the membrane manufacturer's approved-products list can void the membrane warranty at the perimeter.

−

−# Common Errors and RFI Generators {toc}

−

−## Architectural sheet metal generates a consistent set of field errors and RFIs. {note}

−## The following are among the most frequently encountered. {note}

−

−## Field-fabricated coping or gravel stop on a low-slope roof: the Contractor shall not field-fabricate roof-edge metal on a low-slope roof, because such metal without an ES-1 listing for the as-built profile is not IBC-compliant; an ES-1-listed manufactured product or engineered profile is required.

−## Sealant bridging across expansion joints: expansion joints shall be sealed only on the upstream side with butyl tape, and the moving portion of the joint shall not be sealed, because a sealant bridge constrains thermal movement and will be torn open at the first significant temperature swing.

−## Termination bar on a horizontal surface: the counterflashing scope shall not include a termination bar on a horizontal surface (such as flat on a parapet top); counterflashings shall be vertical and terminate into a reglet or under a through-wall flashing.

−## Drip edge insufficient projection: drip edges on copings, fasciae, and through-wall flashings shall project at least 1/2 inch and be turned downward at least 30 degrees from horizontal, or they conduct water back along the underside to the substrate.

−## Missing head flashing end dams: every head flashing shall have an end dam on each end, formed and sealed at the flashing's back leg, or water runs off the side of the flashing into the wall cavity.

−## Galvanized fasteners in copper or stainless sheet: fastener material shall always be at least as noble as the sheet, never less noble, because a galvanized fastener in copper or stainless forms an aggressive galvanic couple that fails the fastener head within years and tracks rust staining down the metal face.

−## ACQ-treated nailer in contact with aluminum coping cleat: the aluminum-ACQ contact shall be isolated with a polymer barrier, or a non-ACQ preservative shall be specified for the nailer, because aluminum cleats on ACQ lumber corrode at the contact face within months in wet exposures.

−## Solder flux not cleaned after copper soldering: all flux residue shall be neutralized and washed off after the joint cools, because rosin flux residue absorbs moisture and accelerates corrosion under the solder line, eventually breaking the solder bond.

−## Coping pieces installed without a slope: coping shall be installed with a minimum 1/4 inch per foot transverse slope, typically toward the roof side, because level coping caps retain water that accelerates finish degradation and water entry at joints and fasteners.

−## Gutter or downspout undersized for the contributory area: sizing shall be confirmed against the SMACNA tables or a roof drainage calculation before fabrication, because undersized gutters overflow during design storms and route water onto the wall below and the foundation.

−## Mortar smears on prefinished coil left to cure: mortar smears shall be removed with water within minutes of contact, not at end of day, because mortar on prefinished aluminum or Galvalume bleaches the finish and produces a permanent visual mark even after removal.

−## Copper runoff onto aluminum, zinc, or galvanized below: the metal below shall be protected by a continuous barrier, or the system layout shall be revised so that copper drainage does not pass over a less noble metal, because copper salts washing onto the metal below drive galvanic corrosion.

−## Coil-coated panels stored flat with weight on top: panels shall be stored on edge or otherwise unloaded during storage, because stacking pressure causes oil-canning, finish indentation, and edge damage along contact lines.

−## Coping cleat fastener pattern not matching ES-1 listing: the Contractor shall verify the as-installed cleat fastener pattern against the listing documentation in the submittal before closing in the work, because substituting fastener type, spacing, or substrate from the ES-1-listed assembly voids the listing.

+---

+title: Sheet Metal Flashing and Trim

+category: Building Envelope

+description: >

+ When to use: Shop- and field-formed architectural sheet metal that closes the building envelope at interfaces - copings on parapets, gravel stops, fasciae and drip edges at roof edges, counterflashings over membrane base flashings, through-wall and head and sill flashings, gutters, downspouts, scuppers and conductor heads, expansion joint covers, and closure and reveal trim. Covers zinc-coated and aluminum-zinc alloy-coated steel, aluminum, stainless steel, copper, and architectural zinc; coil-applied and anodized finishes; forming, hemming, seaming, soldering, and welding; thermal movement and expansion joint provisions; wind securement of low-slope roof edges to ANSI/SPRI ES-1; fastener, cleat, sealant, and underlayment selection; and galvanic separation of dissimilar metals.

+ Not intended for: Field membrane and manufacturer-supplied warranted edge metal furnished as part of a membrane roof system ([[sync/membrane-roofing]]); below-grade waterproofing and its terminations ([[sync/below-grade-waterproofing]]); structural standing-seam metal roof panels and preformed metal wall panel or rainscreen cladding systems, including trim integral to those systems; lightning protection conductors and air terminals; HVAC ductwork; rough carpentry blocking and nailers that support sheet metal; thermal insulation concealed behind sheet metal trim ([[sync/building-thermal-insulation]]).

+---

+# Scope {toc}

+## This standard covers the selection, fabrication, and installation of architectural sheet metal flashing and trim that closes the building envelope at roof edges, parapets, wall openings, material transitions, and drainage collection points. {note}

+## The work is interface work. Nearly every piece sits at the seam between two systems - roof and wall, wall and window, parapet and roof, or two structural bays that move independently - so each piece depends on the dimensional accuracy of adjacent construction and on being installed at the right point in the construction sequence. A coping fabricated exactly to the shop drawing still fails when it is set on out-of-level blocking, sized for the wrong parapet width, or installed after the membrane base flashing on the inside face has been cut short. {note}

+## The following are outside this standard and are covered elsewhere: {note}

+- Field membrane, membrane base flashings, and edge metal furnished by the membrane manufacturer as part of a warranted roof assembly.

+- Structural standing-seam metal roof panels, preformed wall panel systems, and rainscreen cladding, including gutters and trim integral to those systems.

+- Wood nailers, blocking, and curbs that receive sheet metal anchorage.

+- Lightning protection components, HVAC ductwork, and below-grade waterproofing terminations.

+## The Contractor shall verify substrate dimensions, elevations, and conditions in the field before releasing any piece for fabrication.

+## The Contractor shall coordinate the sheet metal sequence with the roofing, masonry, framing, glazing, and cladding trades before fabrication begins.

+## Where a piece within this scope is furnished under another scope of work, the Contractor shall identify that piece in the shop drawings and shall coordinate its interface details with the furnishing trade.

+# Referenced Standards {toc}

+## Materials, fabrication, and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited in the Contract Documents.

+## Where referenced standards conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.

+| Standard | Title |

+|----------|-------|

+| SMACNA Architectural Sheet Metal Manual | Architectural Sheet Metal Manual (forming, joint, cleat, hem, and expansion joint details) |

+| ANSI/SPRI/FM 4435/ES-1 | Wind Design Standard for Edge Systems Used with Low Slope Roofing Systems |

+| FM 4435 | Approval Standard for Edge Systems Used with Low Slope Roofing Systems |

+| ASCE 7 | Minimum Design Loads and Associated Criteria for Buildings and Other Structures |

+| IBC | International Building Code (Chapter 15, Roof Assemblies and Rooftop Structures) |

+| ASTM A653/A653M | Steel Sheet, Zinc-Coated (Galvanized) or Zinc-Iron Alloy-Coated (Galvannealed) by the Hot-Dip Process |

+| ASTM A792/A792M | Steel Sheet, 55% Aluminum-Zinc Alloy-Coated by the Hot-Dip Process |

+| ASTM A924/A924M | General Requirements for Steel Sheet, Metallic-Coated by the Hot-Dip Process |

+| ASTM A755/A755M | Steel Sheet, Metallic Coated by the Hot-Dip Process and Prepainted by the Coil-Coating Process for Exterior Exposed Building Products |

+| ASTM A240/A240M | Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip |

+| ASTM A480/A480M | General Requirements for Flat-Rolled Stainless and Heat-Resisting Steel Plate, Sheet, and Strip |

+| ASTM A153/A153M | Zinc Coating (Hot-Dip) on Iron and Steel Hardware |

+| ASTM B209/B209M | Aluminum and Aluminum-Alloy Sheet and Plate |

+| ASTM B370 | Copper Sheet and Strip for Building Construction |

+| ASTM B69 | Rolled Zinc |

+| ASTM B32 | Solder Metal |

+| ASTM C920 | Elastomeric Joint Sealants |

+| ASTM C1193 | Use of Joint Sealants |

+| ASTM C1087 | Determining Compatibility of Liquid-Applied Sealants with Accessories Used in Structural Glazing Systems |

+| ASTM D1970/D1970M | Self-Adhering Polymer Modified Bituminous Sheet Materials Used as Steep Roofing Underlayment for Ice Dam Protection |

+| ASTM D4214 | Evaluating the Degree of Chalking of Exterior Building Paint Films |

+| ASTM D2244 | Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates |

+| ASTM E2140 | Water Penetration of Metal Roof Panel Systems by Static Water Pressure Head |

+| AAMA 2603 | Pigmented Organic Coatings on Aluminum Extrusions and Panels |

+| AAMA 2604 | High Performance Organic Coatings on Aluminum Extrusions and Panels |

+| AAMA 2605 | Superior Performing Organic Coatings on Aluminum Extrusions and Panels |

+| AAMA 611 | Anodized Architectural Aluminum |

+| AAMA 501.2 | Field Check of Metal Curtain Walls for Water Leakage |

+| NRCA Roofing Manual | Membrane Roof Systems (architectural metal flashing details and edge metal guidance) |

+| CDA Copper in Architecture Handbook | Copper Development Association handbook for architectural copper design and detailing |

+| SSINA Designer Handbook | Specialty Steel Industry of North America handbook for stainless steel fabrication and finishing |

+# Submittals {toc}

+## Action Submittals {toc}

+### The Contractor shall submit the following for the Engineer of Record's review and approval before ordering material or releasing any piece for fabrication:

+- Product data for each sheet metal type, identifying the governing ASTM specification, base metal thickness, coating designation, alloy and temper, and finish system.

+- Finish system data for each coil-applied or anodized finish, including the AAMA specification conformance, color, gloss, and the finish manufacturer's warranty form.

+- ANSI/SPRI ES-1 test report and product label documentation for each roof-edge profile, showing the tested resistance against the design pressure computed for the building's perimeter and corner zones.

+- Shop drawings showing each fabricated piece in plan, section, and elevation, with dimensions, girths, metal thickness, hem and return geometry, joint type and location, cleat type and fastener spacing, expansion joint locations, and corner and termination conditions.

+- Layout drawings locating every expansion joint, cleat run, downspout, scupper, conductor head, and field joint on the building elevations.

+- Samples of each metal and finish on the actual specified substrate, sized large enough to judge color, gloss, and texture in daylight.

+- Fabricator and installer qualification statements with project references for the metal types and joining methods in this scope.

+- Sealant compatibility and adhesion test data for each sealant in contact with a coil-applied, anodized, or bare metal surface, including any primer the sealant manufacturer requires.

+- Fabrication girth and yield plan for copper, zinc, and stainless steel scopes, confirming that pan widths and seam locations match the details being followed.

+```datasheet

+label: Action Submittals Required

+type: checkbox

+options:

+ - "Product data for each sheet metal type"

+ - "Finish system data and finish manufacturer warranty form"

+ - "ANSI/SPRI ES-1 test report and product label documentation for each roof-edge profile"

+ - "Shop drawings of each fabricated piece"

+ - "Layout drawings locating expansion joints, cleats, and drainage components"

+ - "Samples of each metal and finish on the specified substrate"

+ - "Fabricator and installer qualification statements"

+ - "Sealant compatibility and adhesion test data"

+ - "Fabrication girth and yield plan for copper, zinc, and stainless steel"

+default:

+ - "Product data for each sheet metal type"

+ - "Finish system data and finish manufacturer warranty form"

+ - "ANSI/SPRI ES-1 test report and product label documentation for each roof-edge profile"

+ - "Shop drawings of each fabricated piece"

+ - "Layout drawings locating expansion joints, cleats, and drainage components"

+ - "Samples of each metal and finish on the specified substrate"

+ - "Fabricator and installer qualification statements"

+```

+### A roof-edge submittal that omits the ES-1 test documentation for the profile, cleat, fastener pattern, and substrate actually proposed shall be returned as incomplete.

+### The Contractor shall not release roof-edge metal for fabrication before the ES-1 documentation is accepted.

+## Informational Submittals {toc}

+### The Contractor shall submit the following for record before installation begins:

+- Pre-installation conference minutes, including the agreed sequence with the roofing, masonry, and cladding trades.

+- Written substrate acceptance or a written notice of deficient substrate conditions for each area before sheet metal is set in that area.

+- Certification of the solder alloy and flux proposed for each soldered metal.

+- The finish manufacturer's written statement that the project exposure falls within the finish warranty's covered conditions.

+```datasheet

+label: Informational Submittals Required

+type: checkbox

+options:

+ - "Pre-installation conference minutes"

+ - "Written substrate acceptance or notice of deficient conditions"

+ - "Solder alloy and flux certification"

+ - "Finish manufacturer statement on project exposure"

+default:

+ - "Pre-installation conference minutes"

+ - "Written substrate acceptance or notice of deficient conditions"

+ - "Finish manufacturer statement on project exposure"

+```

+## Closeout Submittals {toc}

+### The Contractor shall submit the following at substantial completion, before the sheet metal work is accepted:

+- Executed finish manufacturer warranty covering film integrity, chalk, and color change.

+- Executed workmanship warranty from the Contractor covering fabrication, joinery, and installation.

+- Record shop drawings marked to show as-installed expansion joint locations, every field-formed or field-cut piece, and every field repair.

+- Maintenance instructions for cleaning, periodic inspection, and sealant joint renewal, prepared by the fabricator or the finish manufacturer.

+- Touch-up material in the specified colors, in sealed factory containers, labeled with the finish system and color designation.

+```datasheet

+label: Closeout Submittals Required

+type: checkbox

+options:

+ - "Executed finish manufacturer warranty"

+ - "Executed Contractor workmanship warranty"

+ - "Record shop drawings marked with as-installed conditions"

+ - "Maintenance instructions for cleaning, inspection, and sealant renewal"

+ - "Touch-up material in sealed labeled containers"

+default:

+ - "Executed finish manufacturer warranty"

+ - "Executed Contractor workmanship warranty"

+ - "Record shop drawings marked with as-installed conditions"

+ - "Maintenance instructions for cleaning, inspection, and sealant renewal"

+ - "Touch-up material in sealed labeled containers"

+```

+# Quality Assurance {toc}

+## Fabricator and Installer Qualifications {toc}

+```datasheet

+label: Minimum Fabricator Experience in the Specified Metals and Joining Methods

+type: range

+unit: years

+min: 0

+max: 15

+setpoints: [0, 2, 3, 5, 10, 15]

+default: 5

+```

+```datasheet

+label: Minimum Installer Experience on Comparable Architectural Sheet Metal Work

+type: range

+unit: years

+min: 0

+max: 15

+setpoints: [0, 2, 3, 5, 10, 15]

+default: 5

+```

+### The fabricator shall have the experience indicated in the datasheet in the metal types, thicknesses, finishes, and joining methods specified for this project.

+### The fabricator shall have brake and roll-forming capacity for the longest and heaviest piece shown on the shop drawings.

+### Soldering of copper, lead-coated copper, and stainless steel shall be performed by operators who have soldered the same metal at the same thickness on previous work.

+### Welding of stainless steel and aluminum shall be performed by welders qualified for the process, position, and thickness shown on the shop drawings.

+### The installer shall coordinate directly with the roofing Contractor at every interface between this scope and the membrane assembly.

+### Where the roof carries a membrane manufacturer's no-dollar-limit warranty, edge metal integrated into the warranted assembly shall be installed by an installer the membrane manufacturer accepts for that assembly, or under a written coordination arrangement the membrane manufacturer confirms preserves the warranty.

+## Pre-Installation Conference {toc}

+### A pre-installation conference shall be held before any sheet metal is set.

+### Attendance shall include the sheet metal installer, the roofing Contractor, the masonry or cladding contractor, the General Contractor, the Engineer of Record, and the Owner's representative.

+### The conference shall establish the installation sequence with the roofing and wall trades, confirm expansion joint locations, review the ES-1 fastener pattern, confirm sealant joint design and dissimilar-metal separation, and set the field cutting and touch-up policy.

+### The General Contractor shall distribute conference minutes to all attendees within five business days of the conference.

+## Mock-Up and First-of-Type Review {toc}

+```datasheet

+label: Mock-Up Required Before Production Fabrication

+type: radio

+options:

+ - "Freestanding mock-up erected at a location selected by the Engineer of Record"

+ - "In-place first-of-type installation reviewed before production work continues"

+ - "Not required"

+```

+```datasheet

+label: Conditions to Be Represented in the Mock-Up

+type: checkbox

+options:

+ - "Outside corner"

+ - "Inside corner"

+ - "Expansion joint"

+ - "Running field joint"

+ - "End termination against an adjacent material"

+ - "Drip edge and hem"

+ - "Exposed fastener condition"

+ - "Cleat and anchorage concealed behind the finished face"

+default:

+ - "Outside corner"

+ - "Expansion joint"

+ - "Running field joint"

+ - "End termination against an adjacent material"

+ - "Drip edge and hem"

+```

+### Where a mock-up is indicated in the datasheet, production fabrication shall not proceed until the Engineer of Record has accepted the mock-up in writing.

+### The mock-up shall represent each condition selected in the datasheet, using the specified metal, thickness, finish, joint type, and anchorage.

+### An accepted in-place mock-up may remain in the finished work where it is undamaged and conforms to the accepted submittals.

+### The Engineer of Record shall be the initial arbiter of whether an accepted mock-up establishes the standard of workmanship for a disputed area of finished work.

+# Environmental and Service Conditions {toc}

+## Metal selection, finish selection, and fastener selection all depend on the chemistry the assembly will sit in for the life of the building, and the corrosivity of a site is not always obvious from its address - a roof downwind of a cooling tower, a fume stack, or a de-icing operation can be far more aggressive than its geographic setting suggests. {note}

+```datasheet

+label: Atmospheric Corrosivity of the Site

+type: radio

+options:

+ - "Rural or suburban inland"

+ - "Urban"

+ - "Industrial with airborne acid or particulate fallout"

+ - "Marine within one mile of salt water"

+ - "Marine between one and five miles of salt water"

+ - "Inland site with routine de-icing salt exposure"

+ - "Agricultural with ammonia exposure"

+ - "Indoor conditioned space"

+ - "Indoor unconditioned or permanently concealed space"

+```

+```datasheet

+label: Design Surface Temperature Range Used for Thermal Movement

+type: range

+unit: °F

+min: 60

+max: 240

+setpoints: [60, 80, 100, 120, 140, 160, 180, 200, 220, 240]

+```

+### The design surface temperature range in the datasheet shall govern the calculation of thermal movement, joint spacing, and slip-joint travel for every running piece in this scope.

+### The Contractor shall report to the Engineer of Record any known local source of corrosive discharge within one hundred feet of the sheet metal work that the datasheet exposure category does not already reflect.

+### Surface temperature range is wider than air temperature range, because a dark exposed metal surface in full sun reaches well above ambient and a clear-sky surface at night radiates below it. Basing joint spacing on the annual air temperature swing alone understates the movement the joint actually sees. {note}

+# Sheet Metal Selection by Assembly {toc}

+## Selection Basis {toc}

+### Each assembly family in this scope makes its own metal selection, because the governing considerations differ. Roof-edge metal is a wind-securement component; counterflashing is a removable protective cover; gutters carry standing water and ice; closure trim is often the most visible metal on the building and the least structurally loaded. A single project-wide metal is a legitimate choice, and so is a different metal for each family. {note}

+### Galvanic compatibility constrains the set of selections that can coexist on one building. Copper in contact with aluminum, zinc, or zinc-coated steel, copper-bearing runoff washing onto those metals from above, and carbon steel fasteners in stainless or aluminum sheet all drive corrosion that continues for the life of the assembly. {note}

+### The metal type for each assembly family shall be as indicated in the datasheet.

+```datasheet

+label: Roof-Edge and Coping Sheet Metal

+type: radio

+options:

+ - "Prefinished coil-coated zinc-coated steel"

+ - "Prefinished coil-coated aluminum-zinc alloy-coated steel"

+ - "Mill-finish zinc-coated steel"

+ - "Mill-finish aluminum-zinc alloy-coated steel"

+ - "Prefinished coil-coated aluminum"

+ - "Anodized aluminum"

+ - "Mill-finish aluminum"

+ - "Stainless steel"

+ - "Terne-coated stainless steel"

+ - "Copper"

+ - "Lead-coated copper"

+ - "Architectural zinc"

+```

+```datasheet

+label: Counterflashing and Wall Flashing Sheet Metal

+type: radio

+options:

+ - "Prefinished coil-coated zinc-coated steel"

+ - "Prefinished coil-coated aluminum-zinc alloy-coated steel"

+ - "Mill-finish zinc-coated steel"

+ - "Mill-finish aluminum-zinc alloy-coated steel"

+ - "Prefinished coil-coated aluminum"

+ - "Anodized aluminum"

+ - "Mill-finish aluminum"

+ - "Stainless steel"

+ - "Terne-coated stainless steel"

+ - "Copper"

+ - "Lead-coated copper"

+ - "Architectural zinc"

+```

+```datasheet

+label: Gutter, Downspout, and Scupper Sheet Metal

+type: radio

+options:

+ - "Prefinished coil-coated zinc-coated steel"

+ - "Prefinished coil-coated aluminum-zinc alloy-coated steel"

+ - "Mill-finish zinc-coated steel"

+ - "Mill-finish aluminum-zinc alloy-coated steel"

+ - "Prefinished coil-coated aluminum"

+ - "Anodized aluminum"

+ - "Mill-finish aluminum"

+ - "Stainless steel"

+ - "Terne-coated stainless steel"

+ - "Copper"

+ - "Lead-coated copper"

+ - "Architectural zinc"

+```

+```datasheet

+label: Closure, Reveal, and Miscellaneous Trim Sheet Metal

+type: radio

+options:

+ - "Prefinished coil-coated zinc-coated steel"

+ - "Prefinished coil-coated aluminum-zinc alloy-coated steel"

+ - "Mill-finish zinc-coated steel"

+ - "Mill-finish aluminum-zinc alloy-coated steel"

+ - "Prefinished coil-coated aluminum"

+ - "Anodized aluminum"

+ - "Mill-finish aluminum"

+ - "Stainless steel"

+ - "Terne-coated stainless steel"

+ - "Copper"

+ - "Lead-coated copper"

+ - "Architectural zinc"

+```

+### The Contractor shall not substitute a metal type, coating class, or finish system for the selections in the datasheet without written approval from the Engineer of Record.

+### A request to substitute shall state the galvanic relationship between the proposed metal and every metal it will contact or drain onto.

+## Sheet Thickness Basis {toc}

+### Sheet thickness for each piece shall be not less than the SMACNA Architectural Sheet Metal Manual value for that piece type, girth, span between supports, and metal, and shall be not less than the thickness indicated in the datasheet for the metal used.

+### The Contractor shall increase thickness above the datasheet value where the shop drawing girth or span exceeds the range the datasheet thickness covers, at no change in Contract Sum where the girth is shown in the Contract Documents.

+### Thickness is the cheapest stiffness available in formed sheet metal. Thin sheet on a long span shows oil-canning across the flat face, distorts at seams under thermal load, and pulls at cleats in wind. Heavier sheet resists all three but demands a larger inside bend radius and greater brake capacity, and it costs more per square foot. {note}

+# Zinc-Coated and Aluminum-Zinc Alloy-Coated Steel Sheet {toc}

+## Steel Substrate and Metallic Coating {toc}

+```datasheet

+label: Zinc Coating Designation for Zinc-Coated Steel Sheet

+type: radio

+options:

+ - "G30"

+ - "G60"

+ - "G90"

+ - "G115"

+ - "G165"

+ - "G185"

+default: "G90"

+```

+```datasheet

+label: Coating Designation for Aluminum-Zinc Alloy-Coated Steel Sheet

+type: radio

+options:

+ - "AZ50"

+ - "AZ55"

+ - "AZ60"

+default: "AZ50"

+```

+```datasheet

+label: Steel Sheet Minimum Thickness

+type: select

+unit: gauge

+options:

+ - "28 ga"

+ - "26 ga"

+ - "24 ga"

+ - "22 ga"

+ - "20 ga"

+ - "18 ga"

+ - "16 ga"

+```

+### Zinc-coated steel sheet shall conform to ASTM A653/A653M with the coating designation indicated in the datasheet, and the general requirements of ASTM A924/A924M shall apply.

+### Aluminum-zinc alloy-coated steel sheet shall conform to ASTM A792/A792M with the coating designation indicated in the datasheet.

+### Where flashing or trim is exposed to exterior weather, the zinc coating designation shall be not less than G90.

+### Where flashing or trim is exposed to exterior weather, the aluminum-zinc alloy coating designation shall be not less than AZ50.

+### The base steel shall be commercial steel or forming steel of a grade suited to the forming severity shown on the shop drawings.

+### Prepainted steel sheet shall conform to ASTM A755/A755M for the metallic coating, primer, and topcoat system.

+### A coating designation states the mass of metallic coating per unit area over both surfaces, so a higher number is more coating and more time before the base steel is exposed. Cut edges are protected sacrificially by the adjacent coating rather than by coating over the edge, which is why a cut edge standing in water lasts far less time than the same edge shedding water. {note}

+### Cut edges of zinc-coated and aluminum-zinc alloy-coated steel shall not be left in locations where water stands.

+### Where a bare cut edge is unavoidable in an exposed location, it shall receive a zinc-rich touch-up coating or the finish manufacturer's approved edge treatment.

+### The aluminum-rich coating on aluminum-zinc alloy-coated steel outlasts an equivalent zinc coating in most atmospheric exposures, and loses that advantage in continuously alkaline contact, where high-pH water dissolves the aluminum-rich phase. Mortar runoff, fresh concrete, and animal-confinement environments are the common alkaline conditions on a building. {note}

+### Aluminum-zinc alloy-coated steel shall be separated from fresh mortar, fresh concrete, and continuously wet alkaline surfaces by a barrier that prevents alkaline runoff from reaching the metal.

+# Aluminum Sheet {toc}

+## Aluminum Alloy, Temper, and Thickness {toc}

+```datasheet

+label: Aluminum Alloy and Temper

+type: radio

+options:

+ - "1100-H14"

+ - "3003-H14"

+ - "3004-H16"

+ - "3105-H14"

+ - "5005-H14"

+ - "5005-H34"

+ - "5052-H32"

+```

+```datasheet

+label: Aluminum Sheet Minimum Thickness

+type: range

+unit: in

+min: 0.019

+max: 0.125

+setpoints: [0.019, 0.024, 0.032, 0.04, 0.05, 0.063, 0.08, 0.125]

+```

+### Aluminum sheet shall conform to ASTM B209/B209M in the alloy and temper indicated in the datasheet.

+### Where an anodized finish is specified, the alloy and temper shall be one the anodizer confirms in writing will produce uniform color across the full order.

+### Aluminum shall not be placed in direct contact with fresh mortar, fresh concrete, or lumber treated with a copper-bearing preservative unless a separation material conforming to the galvanic separation requirements of this standard is installed between them.

+### Aluminum is light enough to handle in long lengths, holds a coil-applied finish well, and forms readily in the thicknesses used for flashing. Its coefficient of thermal expansion is roughly twice that of steel, so an aluminum run of a given length needs proportionally more movement capacity than a steel run of the same length. {note}

+### Aluminum trim shall not be used as a structural support for another element unless the shop drawings show the support condition and it has been reviewed by the Engineer of Record.

+# Stainless Steel Sheet {toc}

+## Stainless Grade and Surface Finish {toc}

+```datasheet

+label: Stainless Steel Grade

+type: radio

+options:

+ - "Type 304"

+ - "Type 304L"

+ - "Type 316"

+ - "Type 316L"

+ - "Type 430"

+ - "Type 2205 duplex"

+```

+```datasheet

+label: Stainless Steel Surface Finish

+type: radio

+options:

+ - "No. 2B mill finish"

+ - "No. 2D mill finish"

+ - "No. 3 coarse polished"

+ - "No. 4 brushed satin"

+ - "No. 6 fine satin"

+ - "No. 8 mirror polished"

+ - "Bead blasted"

+ - "Rigidized or embossed pattern"

+default: "No. 2B mill finish"

+```

+```datasheet

+label: Stainless Steel Sheet Minimum Thickness

+type: range

+unit: in

+min: 0.012

+max: 0.075

+setpoints: [0.012, 0.015, 0.0187, 0.025, 0.0312, 0.0375, 0.05, 0.075]

+```

+### Stainless steel sheet shall conform to ASTM A240/A240M, with surface finish designations and finish tolerances per ASTM A480/A480M.

+### Where the sheet metal is exposed to chloride from salt water, salt spray, or de-icing operations, the grade shall be one containing molybdenum.

+### Where the finished face will be viewed at close range in reflected light, the finish shall be selected and sampled with the Engineer of Record before fabrication, and the direction of the polishing grain shall be shown on the shop drawings.

+### Protective film on polished stainless steel shall remain in place through fabrication and installation and shall be removed at substantial completion.

+### Stainless steel outlasts every other common architectural sheet metal in chloride exposure, and it is also the hardest of them to work: it work-hardens under the brake, needs a larger inside bend radius before it cracks, resists soldering in heavier thicknesses, and costs the most per pound. A polished finish also shows every forming mark, so the finish decision and the forming decision are made together. {note}

+# Copper Sheet {toc}

+## Copper Weight, Temper, and Surface Condition {toc}

+```datasheet

+label: Copper Sheet Weight

+type: range

+unit: 'oz/ft²'

+min: 12

+max: 48

+setpoints: [12, 16, 20, 24, 32, 48]

+```

+```datasheet

+label: Copper Temper

+type: radio

+options:

+ - "O60 soft temper"

+ - "H00 cold-rolled temper"

+ - "H01 cold-rolled high-yield temper"

+default: "H00 cold-rolled temper"

+```

+```datasheet

+label: Copper Surface Condition at Installation

+type: radio

+options:

+ - "Mill finish, left to weather naturally"

+ - "Factory pre-patinated"

+ - "Factory pre-oxidized to a brown tone"

+ - "Lead-coated"

+ - "Tin-zinc coated"

+default: "Mill finish, left to weather naturally"

+```

+### Copper sheet shall conform to ASTM B370 in the weight, temper, and surface condition indicated in the datasheet.

+### Copper weight in the datasheet is nominal weight per square foot; the corresponding nominal thickness is as follows:

+| Nominal weight | Nominal thickness |

+|----------------|-------------------|

+| 12 oz/ft² | 0.0162 in |

+| 16 oz/ft² | 0.0216 in |

+| 20 oz/ft² | 0.0270 in |

+| 24 oz/ft² | 0.0323 in |

+| 32 oz/ft² | 0.0431 in |

+| 48 oz/ft² | 0.0646 in |

+### Copper shall not be installed in direct contact with aluminum, zinc, zinc-coated steel, or uncoated carbon steel.

+### Where copper drains onto a less noble metal, the metal below shall be protected by a continuous non-reactive separation layer, or the drainage path shall be revised so that copper runoff does not reach it.

+### Where copper drains onto a porous surface that will remain visible, the copper drip line shall be detailed to carry water clear of that surface, or the surface shall be protected by an intervening element.

+### The Contractor shall confirm in writing that the Owner has been informed of the weathering sequence before mill-finish copper is released for fabrication.

+### Mill-finish copper passes through bright metal, then a range of browns, then a green or blue-green carbonate patina, over a period that runs from several years to several decades depending on exposure and rainfall. The patina is itself the protective layer, and the transition is uneven where rainfall reaches the surface unevenly. Factory pre-patination shortens the wait and narrows the variation; it does not eliminate later change. {note}

+### Lead-coated copper shall be used only where the project's environmental and worker-protection requirements for lead-bearing materials have been reviewed and satisfied, and those requirements shall be identified in the submittal.

+# Architectural Zinc Sheet {toc}

+## Zinc Alloy, Thickness, and Underside Ventilation {toc}

+```datasheet

+label: Architectural Zinc Sheet Thickness

+type: range

+unit: mm

+min: 0.6

+max: 1.5

+setpoints: [0.6, 0.7, 0.8, 1.0, 1.2, 1.5]

+```

+```datasheet

+label: Architectural Zinc Surface Condition at Installation

+type: radio

+options:

+ - "Mill finish, left to weather naturally"

+ - "Factory pre-weathered to a light gray tone"

+ - "Factory pre-weathered to a dark gray tone"

+ - "Factory coated in a pigmented finish"

+```

+```datasheet

+label: Underside Ventilation Provision Beneath Architectural Zinc

+type: radio

+options:

+ - "Ventilated cavity formed by a drainage and ventilation mat"

+ - "Ventilated cavity formed by counter-battens"

+ - "Structured separation layer over a solid deck"

+ - "Not applicable because the zinc face is fully exposed on both sides"

+```

+### Architectural zinc sheet shall conform to ASTM B69 in the thickness indicated in the datasheet.

+### The underside of architectural zinc shall be ventilated by the provision indicated in the datasheet, installed to the zinc manufacturer's published details.

+### Architectural zinc shall not be installed over an underlayment or substrate that holds moisture against its underside.

+### Architectural zinc shall not be placed in contact with copper, copper-bearing runoff, oak or chestnut, or continuously wet alkaline surfaces.

+### Zinc protects itself with a carbonate patina that forms in atmospheric exposure and reforms over scratches. That patina needs alternating wetting and drying to develop. Where the underside stays wet, the patina does not form and a rapidly progressing white corrosion attacks the metal instead, which is why the ventilation provision matters more for zinc than for any other sheet metal in this scope. {note}

+### Rolled zinc expands anisotropically. Along the rolling direction its coefficient of thermal expansion is roughly 19 × 10⁻⁶ in/in/°F, and across the rolling direction roughly 12 × 10⁻⁶, so the rolling direction of each piece is part of the movement calculation and not an incidental fabrication detail. {note}

+### The rolling direction of each zinc piece shall be shown on the shop drawings.

+# Coil-Applied and Anodized Finishes {toc}

+## Coil-Applied Organic Coatings {toc}

+```datasheet

+label: Coil-Applied Coating Performance Class

+type: radio

+options:

+ - "AAMA 2603"

+ - "AAMA 2604"

+ - "AAMA 2605"

+```

+```datasheet

+label: Coating Color and Gloss Selection

+type: text

+drawing_ref: "finish schedule"

+default: deferred

+```

+```datasheet

+label: Coating System Applied to the Concealed Face

+type: radio

+options:

+ - "Wash coat primer"

+ - "Full backer coat"

+ - "Same topcoat system as the exposed face"

+```

+### Coil-applied organic coatings shall conform to the AAMA performance class indicated in the datasheet, applied over the pretreatment and primer the coating manufacturer specifies for the substrate.

+### The three AAMA classes are distinguished by the length of South Florida exposure the coating must survive within stated limits on color change, chalk, gloss retention, and film integrity: one year for AAMA 2603, five years for AAMA 2604, and ten years for AAMA 2605. Longer qualifying exposure buys longer service appearance and costs more per square foot. {note}

+### Where the finished face is exposed to direct sunlight and is visible from a public way or an occupied space, the coating class shall be not less than AAMA 2604.

+### Where the coating is selected in a saturated or organic pigment color, the Contractor shall obtain the coating manufacturer's specific color data, because color change limits are more difficult to hold in those pigment families.

+### The Contractor shall confirm coil order quantity, color, and lead time at the time of submittal, and shall report to the General Contractor any lead time that affects the construction schedule.

+## Anodized Aluminum Finishes {toc}

+```datasheet

+label: Anodized Coating Class

+type: radio

+options:

+ - "AAMA 611 Class I"

+ - "AAMA 611 Class II"

+default: "AAMA 611 Class I"

+```

+```datasheet

+label: Anodized Finish Color

+type: radio

+options:

+ - "Clear"

+ - "Champagne"

+ - "Light bronze"

+ - "Medium bronze"

+ - "Dark bronze"

+ - "Black"

+```

+### Anodized aluminum shall conform to AAMA 611 at the coating class indicated in the datasheet.

+### Where anodized aluminum is exposed to exterior weather, the coating class shall be AAMA 611 Class I.

+### All anodized aluminum visible on a single building elevation shall be produced from one lot, and the Contractor shall confirm lot continuity before the order is released.

+### The Contractor shall obtain the Engineer of Record's written acceptance of the color variation range before anodized material is ordered.

+### Anodizing converts the aluminum surface rather than covering it, so its color comes from the metal, the alloy, and the bath, and it varies measurably between coils and between lots. That variation is a property of the process, not a defect, and it is managed by lot control rather than by rejection after delivery. {note}

+## Mill and Natural Surfaces {toc}

+### Where a mill or naturally weathering surface is specified, the Contractor shall confirm in writing that the Owner has been informed of the appearance sequence and has accepted the initial unweathered appearance.

+### A mill or naturally weathering surface cannot later be converted to the appearance of a factory-applied finish in place. The substitution decision is made before fabrication or not at all. {note}

+## Field Touch-Up of Applied Finishes {toc}

+```datasheet

+label: Largest Damaged Area Eligible for Field Touch-Up on an Exposed Surface

+type: range

+unit: in

+min: 0

+max: 2

+setpoints: [0, 0.25, 0.5, 1, 2]

+default: 0.25

+```

+### Touch-up material shall be the coating manufacturer's product for the specified coating system and color.

+### Touch-up on an exposed surface shall be limited to damage no larger than the dimension indicated in the datasheet in any direction.

+### A piece with exposed-face damage larger than the datasheet dimension shall be replaced rather than touched up.

+### Cut edges concealed within a hem, fastener heads concealed beneath sealant, and other surfaces not in direct sunlight may receive touch-up at any size.

+### A field-applied touch-up weathers on a different curve than the factory-cured coating around it, so an eye-level patch that matches on the day it is applied separates visibly within a few seasons. That is why the eligible size is small and tied to visibility rather than to the cost of replacement. {note}

+# Fasteners, Cleats, and Anchorage {toc}

+## Attachment Method {toc}

+```datasheet

+label: Attachment Method for Exposed Sheet Metal Faces

+type: radio

+options:

+ - "Concealed attachment using continuous cleats, hook strips, or clips"

+ - "Exposed fasteners with bonded sealing washers"

+ - "Concealed attachment at the running face with exposed fasteners at terminations"

+```

+### Where the sheet metal face is visible in the finished work, concealed attachment removes the exposed-fastener field entirely, which removes the sealing washers that age, the fastener heads that hold water and stain, and the visual rhythm of a fastener line across the face. Exposed fasteners cost less to install and are faster to remove for service. {note}

+### Attachment shall be as indicated in the datasheet.

+### Exposed fasteners shall be color-matched to the adjacent finish or concealed beneath a trim closure.

+### Fasteners shall not penetrate the water-bearing surface of a gutter, pan flashing, or scupper.

+## Fastener Material and Corrosion Compatibility {toc}

+```datasheet

+label: Exposed Fastener Material

+type: radio

+options:

+ - "Type 304 stainless steel with bonded sealing washer"

+ - "Type 316 stainless steel with bonded sealing washer"

+ - "Aluminum with bonded sealing washer"

+ - "Silicon bronze"

+ - "Copper or copper alloy"

+ - "Hot-dip galvanized steel with bonded sealing washer"

+default: "Type 304 stainless steel with bonded sealing washer"

+```

+```datasheet

+label: Concealed Fastener Material

+type: radio

+options:

+ - "Type 304 stainless steel"

+ - "Type 316 stainless steel"

+ - "Aluminum"

+ - "Silicon bronze"

+ - "Copper or copper alloy"

+ - "Hot-dip galvanized steel"

+default: "Type 304 stainless steel"

+```

+### Fasteners shall be of the same metal as the sheet they secure, or of a metal not less noble than that sheet.

+### Hot-dip galvanized steel fasteners shall conform to ASTM A153/A153M and shall not be used in copper, stainless steel, or terne-coated stainless steel sheet.

+### Copper sheet shall be fastened with copper, copper alloy, or stainless steel fasteners.

+### Architectural zinc shall be fastened with stainless steel fasteners.

+### Fasteners into wood substrate shall achieve the embedment the ES-1 listing or the shop drawing detail requires, and shall not be substituted with a shorter fastener to suit a field condition.

+### A fastener less noble than the sheet becomes the anode for the whole assembly. The fastener is a small area against a large cathode, so it corrodes fast, and the sheet then loses its anchorage before it shows any distress of its own. Reversing the relationship reverses the outcome: a noble fastener in a less noble sheet loses only the small ring of sheet in contact with it. {note}

+## Cleats and Hook Strips {toc}

+```datasheet

+label: Cleat Type

+type: radio

+options:

+ - "Continuous cleat running the full length of the piece"

+ - "Intermittent clip cleat"

+default: "Continuous cleat running the full length of the piece"

+```

+```datasheet

+label: Intermittent Cleat Maximum Spacing

+type: range

+unit: 'in o.c.'

+min: 4

+max: 24

+setpoints: [4, 6, 8, 12, 16, 18, 24]

+default: 12

+```

+```datasheet

+label: Intermittent Cleat Minimum Width

+type: range

+unit: in

+min: 1

+max: 6

+setpoints: [1, 1.5, 2, 3, 4, 6]

+default: 2

+```

+### A cleat is a strip of metal fastened to the substrate that engages a hemmed return on the sheet metal piece, holding the piece against uplift without any fastener through the visible face. {note}

+### Cleats shall be of the same metal as the sheet they engage, or of a compatible metal not less noble than that sheet.

+### Cleat thickness shall be not less than the thickness of the sheet it engages.

+### Where the sheet is at the lower end of the thickness range for its girth and span, the cleat shall be one thickness step heavier than the sheet.

+### Continuous cleats shall be installed in lengths matching the piece they engage, butted rather than lapped at cleat-to-cleat joints, and positioned so that a cleat joint does not coincide with a sheet metal joint.

+### Intermittent cleats shall be not narrower than the datasheet width and shall be spaced no farther apart than the datasheet spacing.

+### Intermittent cleats shall be bedded in non-curing tape sealant between the cleat and the substrate.

+### A continuous cleat engages the hem along its whole length, so uplift is carried uniformly by the fold. An intermittent cleat carries the same total load through discrete points, which concentrates the engagement and can telegraph as local distortion along a hem in a long exposed run. {note}

+# Sealants, Tapes, and Underlayment {toc}

+## Elastomeric Sealants at Weather-Exposed Joints {toc}

+```datasheet

+label: Elastomeric Sealant Chemistry at Weather-Exposed Sheet Metal Joints

+type: radio

+options:

+ - "Silicone"

+ - "Polyurethane"

+ - "Silyl-terminated polyether hybrid"

+ - "Polysulfide"

+```

+```datasheet

+label: Sealant Movement Class to ASTM C920

+type: radio

+options:

+ - "Class 12-1/2"

+ - "Class 25"

+ - "Class 50"

+ - "Class 100/50"

+default: "Class 50"

+```

+### Elastomeric sealant shall conform to ASTM C920, Type S or Type M, Grade NS, at the movement class indicated in the datasheet, in Use classes covering the substrates it contacts.

+### Sealant joints shall be designed and installed in accordance with ASTM C1193 for joint width, depth, backing, and tooling.

+### Where the sealant will be painted in service, the chemistry shall be one the coating manufacturer confirms accepts the paint.

+### Where the sealant contacts a porous substrate that would be stained by plasticizer or fluid migration, the sealant shall be one the sealant manufacturer confirms as non-staining on that substrate, tested to ASTM C1087 or the manufacturer's equivalent staining test.

+### Where sealant contacts a fluoropolymer coil coating, the Contractor shall obtain the sealant manufacturer's adhesion test data on the actual specified coating and shall apply any primer that data requires.

+### Fluoropolymer topcoats are chosen partly because very little sticks to them, which is what keeps them clean, and that same property is why sealant adhesion to them has to be demonstrated on the actual coating rather than assumed from a generic substrate list. {note}

+## Non-Curing Sealant Tapes at Concealed Joints {toc}

+```datasheet

+label: Concealed Lap and Slip-Joint Sealant

+type: radio

+options:

+ - "Non-curing butyl sealant tape"

+ - "Non-skinning gunnable butyl sealant"

+ - "Non-curing polyisobutylene sealant tape"

+default: "Non-curing butyl sealant tape"

+```

+```datasheet

+label: Concealed Sealant Tape Minimum Thickness

+type: range

+unit: in

+min: 0.0312

+max: 0.25

+setpoints: [0.0312, 0.0625, 0.09375, 0.125, 0.1875, 0.25]

+default: 0.0625

+```

+### Non-curing sealant tape shall be installed as the concealed seal at lapped joints, at slip joints, beneath cleats, beneath fasteners passing through a hemmed edge, and behind backer plates at expansion joints.

+### Non-curing sealant tape shall be installed at full width and without interruption across the sealed path.

+### A non-curing tape stays plastic for the life of the joint, so a clamped joint can still slide across it as the metal moves. A cured elastomeric bead in the same location bonds both sides together and converts a moving joint into a restrained one, which is why the two are not interchangeable. {note}

+## Underlayment and Slip Sheets {toc}

+```datasheet

+label: Underlayment Beneath Sheet Metal on Wood or Sheathing Substrates

+type: radio

+options:

+ - "Self-adhering polymer-modified bituminous sheet"

+ - "Self-adhering high-temperature polymer-modified bituminous sheet"

+ - "Self-adhering butyl-based high-temperature sheet"

+ - "Mechanically attached synthetic underlayment"

+ - "Rosin-sized building paper slip sheet"

+ - "No separate underlayment because the metal laps a membrane base flashing"

+default: "Self-adhering polymer-modified bituminous sheet"

+```

+```datasheet

+label: Underlayment Minimum Thickness

+type: range

+unit: mil

+min: 15

+max: 60

+setpoints: [15, 20, 25, 30, 40, 45, 60]

+default: 40

+```

+```datasheet

+label: Underlayment Minimum Side Lap

+type: range

+unit: in

+min: 2

+max: 12

+setpoints: [2, 3, 4, 6, 8, 12]

+default: 4

+```

+```datasheet

+label: Underlayment Minimum End Lap

+type: range

+unit: in

+min: 2

+max: 12

+setpoints: [2, 3, 4, 6, 8, 12]

+default: 6

+```

+### Self-adhering polymer-modified bituminous underlayment shall conform to ASTM D1970/D1970M.

+### Underlayment shall be installed over the full area of wood blocking, sheathing, or deck that receives sheet metal, lapped at not less than the datasheet side and end laps, with all laps rolled.

+### Where the design surface temperature range in the datasheet reaches the upper end of its range beneath a dark metal surface, the underlayment shall be a high-temperature product rated by its manufacturer for that surface temperature.

+### Where sheet metal laps a membrane base flashing, a separate underlayment beneath the metal shall not be required, and the cleat or hook strip shall be fastened through the base flashing into structural blocking in accordance with the membrane manufacturer's published detail.

+### A rosin-sized slip sheet shall be installed between copper or architectural zinc and any bituminous underlayment.

+# Fabrication and Joinery {toc}

+## Shop Forming and Brake Work {toc}

+```datasheet

+label: Maximum Shop-Fabricated Piece Length

+type: range

+unit: ft

+min: 8

+max: 40

+setpoints: [8, 10, 12, 16, 20, 24, 30, 40]

+```

+```datasheet

+label: Minimum Inside Bend Radius as a Multiple of Metal Thickness

+type: range

+unit: 'multiples of thickness'

+min: 0.5

+max: 4

+setpoints: [0.5, 1, 1.5, 2, 3, 4]

+default: 1.5

+```

+### Sheet metal shall be brake-formed in the shop except at closures and end conditions that cannot be dimensioned before adjacent construction is complete.

+### The maximum piece length shall be as indicated in the datasheet, and shall be further limited by site access, staging area, and handling capability.

+### Bends shall be formed with the finished face on the outside of the bend where the bend is convex to the finished face.

+### The inside bend radius shall be not less than the datasheet multiple of the metal thickness, and shall be increased where the coating or metal requires it to avoid fracture.

+### A coating that has fractured at the apex of a bend shall be cause for rejection of the piece, and the piece shall not be repaired by touch-up.

+### Cut edges shall be deburred and shall be free of feathered or torn metal.

+### Fewer field joints means longer pieces, which means larger trucks, more people on the lift, and more risk of a handling kink that cannot be dressed out. The trade runs in both directions and is settled per project rather than by a universal length. {note}

+## Running Joints in Formed Trim {toc}

+```datasheet

+label: Running Joint Type Between Expansion Joints

+type: radio

+options:

+ - "Double-lock standing seam"

+ - "Single-lock standing seam"

+ - "Flat-lock seam"

+ - "Lapped joint sealed with concealed tape and a tooled bead"

+ - "Butt joint over a concealed backer plate"

+ - "Soldered flat-lock seam"

+```

+```datasheet

+label: Minimum Lap at Lapped and Sealed Joints

+type: range

+unit: in

+min: 0.5

+max: 6

+setpoints: [0.5, 1, 1.5, 2, 3, 4, 6]

+default: 2

+```

+```datasheet

+label: Minimum Standing Seam Height

+type: range

+unit: in

+min: 0.5

+max: 2

+setpoints: [0.5, 0.75, 1, 1.5, 2]

+default: 1

+```

+### Running joints shall be of the type indicated in the datasheet, and the joint type for each piece shall be shown on the shop drawings.

+### Lapped joints shall lap in the direction of water flow, with the upstream piece outside the downstream piece.

+### Lapped joints shall carry a continuous non-curing sealant tape concealed within the lap and a sealant bead tooled to a clean fillet at the upstream edge.

+### Standing seams shall be not less than the datasheet height and shall be closed by hand or by a seaming machine matched to the metal and thickness.

+### Seams shall not be closed by hammering directly on a finished surface.

+## Hems, Drip Edges, and Returns {toc}

+```datasheet

+label: Standard Edge Hem

+type: radio

+options:

+ - "Single hem folded back on itself"

+ - "Double hem folded twice"

+ - "Open hem with a separate closure strip"

+ - "Hem formed over a continuous stiffener"

+default: "Single hem folded back on itself"

+```

+```datasheet

+label: Standard Hem Depth

+type: range

+unit: in

+min: 0.25

+max: 1.5

+setpoints: [0.25, 0.375, 0.5, 0.75, 1, 1.5]

+default: 0.5

+```

+```datasheet

+label: Minimum Drip Edge Projection Beyond the Face Below

+type: range

+unit: in

+min: 0.25

+max: 2

+setpoints: [0.25, 0.375, 0.5, 0.75, 1, 1.5, 2]

+default: 0.5

+```

+### Every edge that will be exposed in the finished work shall be hemmed so that no raw cut edge is visible or exposed to weather.

+### Hems shall be formed at the depth indicated in the datasheet.

+### Drip edges at copings, fasciae, gravel stops, and through-wall flashings shall project beyond the face below by not less than the datasheet projection.

+### Drip edges shall be turned downward not less than 30° from horizontal.

+### Water leaving a horizontal metal edge follows the underside back toward the wall unless the edge both stands clear of the surface below and points down. A projection with no downturn, or a downturn with no projection, each fails the same way: a stain track down the face below the flashing. {note}

+## Soldered Joints {toc}

+```datasheet

+label: Solder Alloy

+type: radio

+options:

+ - "50/50 tin-lead solder to ASTM B32"

+ - "60/40 tin-lead solder to ASTM B32"

+ - "95/5 tin-antimony solder to ASTM B32"

+ - "Tin-silver lead-free solder to ASTM B32"

+default: "50/50 tin-lead solder to ASTM B32"

+```

+```datasheet

+label: Soldering Flux

+type: radio

+options:

+ - "Zinc chloride acid flux"

+ - "Muriatic acid flux"

+ - "Phosphoric acid flux for stainless steel"

+ - "Rosin flux"

+```

+```datasheet

+label: Minimum Soldered Seam Width

+type: range

+unit: in

+min: 0.5

+max: 2

+setpoints: [0.5, 0.75, 1, 1.5, 2]

+default: 1

+```

+### Soldered joints shall be made in copper, lead-coated copper, tin-zinc coated copper, terne-coated stainless steel, and stainless steel at the thicknesses the fabricator's qualification covers.

+### Solder alloy and flux shall be as indicated in the datasheet, and both shall be confirmed by the solder manufacturer as suited to the base metal being joined.

+### Where the project prohibits lead-bearing materials, a lead-free alloy of equal or greater joint strength shall be used, and the substitution shall be identified in the submittal.

+### Seams to be soldered shall be pre-tinned where the base metal or thickness requires it, mechanically locked before soldering, and heated to full flow temperature so that solder is drawn through the seam by capillary action.

+### Soldered seams shall be not narrower than the datasheet width.

+### Soldered seams shall be inspected for continuous penetration, and any void shall be reheated and re-soldered.

+### Flux residue shall be neutralized and washed from both faces of the joint after the joint has cooled.

+### Zinc-coated steel, aluminum-zinc alloy-coated steel, aluminum, and architectural zinc shall be joined by mechanical seams rather than by soldering.

+### Acid flux residue left on the metal keeps working after the joint cools. It holds moisture against the seam, corrodes the base metal under the solder line, and eventually breaks the bond from the inside, so the wash is part of making the joint rather than part of cleaning up after it. {note}

+## Welded Joints in Stainless Steel {toc}

+### Stainless steel joints too heavy to solder, and stainless steel joints where solder appearance is unacceptable, shall be welded by a qualified welder using a process suited to the thickness.

+### Heat input shall be controlled to limit distortion and to limit sensitization of the heat-affected zone.

+### Welds in exposed work shall be ground, polished to match the adjacent finish, and passivated.

+### The Contractor shall submit a welded sample in the specified grade, thickness, and finish for acceptance before welding production pieces.

+# Thermal Movement and Expansion Joints {toc}

+## Movement Basis {toc}

+### Every running piece of sheet metal changes length with temperature, and the only question is whether the assembly gives that movement somewhere to go or takes it out on the joints, the cleats, and the fasteners. Restrained metal buckles in heat, tears at joints in cold, and works fasteners loose over thousands of cycles. {note}

+### Approximate coefficients of thermal expansion for the metals in this standard are as follows:

+| Metal | Coefficient of thermal expansion |

+|-------|----------------------------------|

+| Carbon and zinc-coated steel | 6.7 × 10⁻⁶ in/in/°F |

+| Type 316 stainless steel | 8.9 × 10⁻⁶ in/in/°F |

+| Type 304 stainless steel | 9.6 × 10⁻⁶ in/in/°F |

+| Copper | 9.8 × 10⁻⁶ in/in/°F |

+| Aluminum | 13 × 10⁻⁶ in/in/°F |

+| Rolled zinc along the rolling direction | 19 × 10⁻⁶ in/in/°F |

+### The Contractor shall calculate the movement of each running piece from the metal's coefficient of thermal expansion, the piece length, and the design surface temperature range in the datasheet, and shall show the calculated movement on the shop drawings.

+### Expansion joint spacing shall be not greater than the value indicated in the datasheet and not greater than the SMACNA Architectural Sheet Metal Manual value for the metal, girth, and design temperature range.

+```datasheet

+label: Maximum Spacing Between Expansion Joints in Running Trim

+type: range

+unit: ft

+min: 6

+max: 60

+setpoints: [6, 8, 10, 12, 16, 20, 25, 30, 40, 50, 60]

+```

+```datasheet

+label: Expansion Joint Type

+type: radio

+options:

+ - "Slip joint with a concealed backer plate"

+ - "Formed cover plate over an open butt joint"

+ - "Interlocking S-lock joint with a concealed backer plate"

+ - "Bellows joint formed in the metal"

+```

+```datasheet

+label: Minimum Travel Provided at Each Expansion Joint

+type: range

+unit: in

+min: 0.25

+max: 3

+setpoints: [0.25, 0.5, 0.75, 1, 1.5, 2, 3]

+default: 1

+```

+```datasheet

+label: Minimum Distance From a Corner to the Nearest Expansion Joint

+type: range

+unit: in

+min: 0

+max: 48

+setpoints: [0, 6, 12, 18, 24, 36, 48]

+default: 18

+```

+### Each expansion joint shall be of the type indicated in the datasheet and shall provide not less than the datasheet travel in each direction from the installed position.

+### Expansion joints shall be sealed on the upstream side with non-curing sealant tape.

+### Cured elastomeric sealant shall not bridge the moving portion of an expansion joint.

+### Corners shall be solidly joined by mitering, soldering, welding, or a double-lock seam.

+### Expansion joints shall be located in the running section not closer to a corner than the datasheet distance.

+### A corner is the stiffest point in a run of formed metal, so if the nearest joint is at the corner the whole movement of both legs arrives at the one detail least able to absorb it. Moving the joint into the straight run puts the travel where the metal can slide. {note}

+# Roof Edge Securement to ANSI/SPRI ES-1 {toc}

+## Code Basis for Edge Securement {toc}

+### ANSI/SPRI/FM 4435/ES-1 sets the wind resistance requirements for metal edge systems on low-slope roofs and defines three test methods. RE-1 evaluates the edge system's ability to restrain an unadhered membrane at the perimeter. RE-2 evaluates resistance to outward horizontal load on gravel stops and fasciae. RE-3 evaluates a coping's resistance to outward horizontal load and to upward load at the building edge. {note}

+### Metal edge securement on low-slope roofs shall be designed for the wind loads determined under the building code's structural provisions and shall be tested to the applicable ES-1 test methods.

+### Edge system components or their packaging shall carry written documentation identifying which components were ES-1 tested, and that documentation shall be delivered to the site with the material.

+### Gutters are excluded from the code's edge securement requirement, and gutter anchorage is governed by the gutter provisions of this standard instead. {note}

+```datasheet

+label: Design Wind Pressure at the Roof Perimeter and Corner Zones

+type: range

+unit: psf

+drawing_ref: "structural design criteria"

+min: 20

+max: 300

+step: 5

+default: deferred

+```

+```datasheet

+label: Safety Factor Applied to the ES-1 Design Pressure

+type: range

+unit: 'multiplier'

+min: 1

+max: 2.5

+setpoints: [1, 1.25, 1.5, 1.67, 2, 2.5]

+```

+### ES-1 as published does not itself require a safety factor on the design pressure, and industry guidance recommends applying one to cover variability in materials, fabrication, and substrate. The datasheet multiplier is where that decision is recorded, and a multiplier of one records a deliberate decision to design to the tested value with no additional margin. {note}

+## Edge System Compliance Path {toc}

+```datasheet

+label: ES-1 Compliance Path for Roof-Edge Metal

+type: radio

+options:

+ - "Manufactured edge system tested and labeled for the specified profile and securement"

+ - "Shop-fabricated profile tested to ES-1 for this fabricator and this configuration"

+ - "Engineered design sealed by a licensed engineer demonstrating equivalent resistance"

+```

+```datasheet

+label: FM Approval Required for Roof-Edge Metal

+type: radio

+options:

+ - "FM 4435 approval required in addition to the ES-1 listing"

+ - "FM 4435 approval not required"

+```

+### Roof-edge metal shall be provided under the compliance path indicated in the datasheet.

+### A tested listing covers one combination of profile, metal, thickness, cleat, fastener type, fastener spacing, and substrate. Substituting any one of those puts the affected length of roof edge outside the listing, whatever the substituted component's own rating is. {note}

+### The Contractor shall not substitute any component of a listed edge assembly without a revised listing or a sealed engineering analysis covering the substitution.

+### Where FM 4435 approval is indicated in the datasheet, the approval listing shall be submitted with the ES-1 documentation.

+### Where a profile shown in the Contract Documents has no available listing and no test data, the Contractor shall report the condition to the Engineer of Record before fabrication rather than fabricating to the profile and treating it as compliant.

+## Nailer and Cleat Anchorage at Roof Edges {toc}

+```datasheet

+label: Wood Nailer Preservative Treatment

+type: radio

+options:

+ - "Copper-based waterborne preservative"

+ - "Micronized copper preservative"

+ - "Non-copper carbon-based preservative"

+ - "Borate preservative"

+ - "Untreated lumber protected from wetting"

+```

+### The Contractor shall verify in the field that nailer width, thickness, elevation, and attachment match the tested assembly documented in the accepted submittal.

+### A deviation between the installed nailer or cleat fastener pattern and the tested assembly shall be reported to the Engineer of Record in writing and corrected before edge metal is set over it.

+### Nailer attachment to the deck or parapet shall not be altered from the tested assembly.

+### Where the nailer preservative contains copper and the cleat is aluminum or zinc-coated steel, a separation material conforming to the galvanic separation requirements of this standard shall be installed between the cleat and the nailer.

+### Copper-bearing waterborne preservatives leave soluble copper and an acidic surface on the lumber. Both attack aluminum, and in a wet exposure a bare aluminum cleat on that lumber shows contact-face corrosion in months rather than years. {note}

+# Coping {toc}

+## Coping Geometry and Slope {toc}

+```datasheet

+label: Coping Transverse Slope Direction

+type: radio

+options:

+ - "Sloped toward the roof side"

+ - "Sloped toward the exterior face"

+ - "Sloped both ways from a raised center"

+ - "Level across the parapet"

+default: "Sloped toward the roof side"

+```

+```datasheet

+label: Coping Transverse Slope

+type: range

+unit: 'in/ft'

+min: 0

+max: 0.5

+step: 0.0625

+default: 0.25

+```

+```datasheet

+label: Coping Overhang Beyond the Exterior Parapet Face

+type: range

+unit: in

+min: 0.5

+max: 4

+setpoints: [0.5, 0.75, 1, 1.5, 2, 3, 4]

+default: 1.5

+```

+```datasheet

+label: Coping Overhang Beyond the Interior Parapet Face

+type: range

+unit: in

+min: 0.5

+max: 4

+setpoints: [0.5, 0.75, 1, 1.5, 2, 3, 4]

+default: 1

+```

+### Coping caps the top of a parapet and protects both the wall construction below it and the membrane base flashing terminating on the inside face. {note}

+### Coping shall be sloped in the direction and at the rate indicated in the datasheet, achieved by tapering the parapet top or by tapered shims beneath the coping.

+### Coping shall overhang each parapet face by not less than the datasheet dimension for that face, and both edges shall be hemmed and turned down to form a drip.

+### Slope toward the roof side puts coping runoff onto the membrane, where the roof drainage system already handles it. Slope toward the exterior face puts the same water down the wall, which loads the wall's water management and concentrates staining on the visible facade. A two-way slope from a raised center halves the flow on each side and creates two drip lines and two edge details instead of one. A level parapet top holds water on the coping, which loads the joints and fasteners rather than the drainage path. {note}

+### Coping is a roof-edge component and shall comply with the roof edge securement requirements of this standard for the design pressure at the parapet edge and corner zones.

+## Coping Joinery and Anchorage {toc}

+```datasheet

+label: Coping Field Joint Type Between Expansion Joints

+type: radio

+options:

+ - "Double-lock standing seam"

+ - "Lapped joint sealed with concealed tape and a tooled bead"

+ - "Butt joint over a concealed backer plate"

+ - "Soldered flat-lock seam"

+```

+### Coping shall be joined between expansion joints by the joint type indicated in the datasheet, with lapped joints running in the direction of slope so that water sheds over the joint rather than into it.

+### The continuous cleat or hook strip engaging the coping shall be part of the tested edge assembly and shall be fastened at the spacing that assembly requires.

+### Coping cleat fasteners shall pass through non-curing sealant tape at the nailer.

+### Corners in coping shall be shop-fabricated as single mitered, soldered, or welded units wherever the corner geometry and shipping allow.

+### The parapet top shall be verified level and true to the shop drawing dimensions before coping is fabricated, and any deviation exceeding the fabrication tolerance shall be corrected by others before coping is set.

+# Counterflashing at Membrane Base Flashings {toc}

+## Counterflashing Termination and Lap {toc}

+```datasheet

+label: Counterflashing Termination at the Wall

+type: radio

+options:

+ - "Reglet saw-cut in concrete or unit masonry"

+ - "Manufactured two-piece receiver built into the masonry"

+ - "Termination beneath a through-wall flashing"

+ - "Surface-mounted with a sealed top edge"

+ - "Formed integrally with the coping as a single piece"

+```

+```datasheet

+label: Counterflashing Minimum Lap Over the Membrane Base Flashing

+type: range

+unit: in

+min: 2

+max: 8

+setpoints: [2, 3, 4, 6, 8]

+default: 4

+```

+```datasheet

+label: Counterflashing Minimum Embedment Into the Reglet or Receiver

+type: range

+unit: in

+min: 0.5

+max: 2

+setpoints: [0.5, 0.75, 1, 1.5, 2]

+default: 1

+```

+### The membrane base flashing is the water barrier at a roof-to-wall interface. The counterflashing is a removable cover that protects the base flashing's top termination from ultraviolet exposure, debris, and impact, and that can be taken off intact when the roof is replaced. {note}

+### Counterflashing shall terminate at the wall by the method indicated in the datasheet, embedded not less than the datasheet depth where it engages a reglet or receiver.

+### Counterflashing shall lap the top of the membrane base flashing by not less than the datasheet lap.

+### The lap between counterflashing and base flashing shall not be sealed, and the lap geometry shall carry water down the exposed face of the base flashing.

+### Counterflashing shall be formed so that any water entering behind it discharges at the bottom of the base flashing onto the roof surface.

+### Where counterflashing is surface-mounted, its top edge sealant joint shall be designed as a maintained joint, and the maintenance instructions shall identify it as requiring periodic renewal.

+### A counterflashing termination bar shall not be installed on a horizontal surface.

+### Reglets shall be cut to the depth the receiver or wedge requires, cleaned of dust and slurry, and shall not be cut through a masonry unit face shell into a cavity.

+# Through-Wall, Head, and Sill Flashings {toc}

+## Through-Wall Flashing at Masonry {toc}

+```datasheet

+label: Exposed Metal Drip Component at Through-Wall Flashings

+type: radio

+options:

+ - "Formed metal drip edge lapped beneath the membrane through-wall flashing"

+ - "Formed metal drip edge lapped over the membrane through-wall flashing"

+ - "Fully metal through-wall flashing with soldered or welded laps"

+ - "Membrane through-wall flashing with an integral formed drip"

+```

+```datasheet

+label: Through-Wall Flashing Drip Projection Beyond the Wall Face

+type: range

+unit: in

+min: 0

+max: 1.5

+setpoints: [0, 0.25, 0.375, 0.5, 0.75, 1, 1.5]

+default: 0.25

+```

+### Through-wall flashing shall be installed within the wall at the wall base, at floor lines, at shelf angles, and at the heads and sills of openings, to intercept water in the wall and return it to the exterior at weep openings.

+### The exposed drip component shall be sheet metal of the type indicated for wall flashing in this standard, lapped with the concealed membrane flashing as indicated in the datasheet.

+### The exposed drip shall project beyond the wall face by not less than the datasheet projection and shall be turned down not less than 30°.

+### Where the architectural treatment of the wall face precludes a projecting drip, the metal shall be set flush with the wall face and the concealed flashing above it shall be extended outward to form the drip in front of the wall face.

+### A flush metal edge with the flashing above stopping behind the wall face is the condition that produces water tracking back into the wall. Setting the metal flush is workable; stopping the drainage plane short of the face is not. {note}

+### Through-wall flashing laps, end dams, and weep spacing shall be coordinated with the masonry scope, and lap and end dam details shall be shown on the sheet metal shop drawings.

+## Head and Sill Flashings at Wall Openings {toc}

+```datasheet

+label: Head Flashing Extension Beyond Each Side of the Rough Opening

+type: range

+unit: in

+min: 0

+max: 6

+setpoints: [0, 1, 2, 3, 4, 6]

+default: 2

+```

+```datasheet

+label: Head Flashing End Dam Minimum Height

+type: range

+unit: in

+min: 0.25

+max: 3

+setpoints: [0.25, 0.5, 1, 1.5, 2, 3]

+default: 1

+```

+```datasheet

+label: Sill Pan Flashing Configuration

+type: radio

+options:

+ - "Formed metal pan with soldered or welded corners"

+ - "Formed metal pan with sealed mechanical corners"

+ - "Formed metal pan with preformed corner boots"

+ - "Formed metal pan with a back leg and end dams turned up from a single sheet"

+```

+```datasheet

+label: Sill Pan Back Leg Minimum Height

+type: range

+unit: in

+min: 0.25

+max: 4

+setpoints: [0.25, 0.5, 1, 1.5, 2, 3, 4]

+default: 1

+```

+### Head flashing shall be continuous over the opening, lapped over the top of the frame, and turned up behind the wall water-resistive barrier so that water on the barrier is carried over the flashing and discharged beyond the frame.

+### Head flashing shall extend beyond each side of the rough opening by not less than the datasheet extension.

+### Head flashing shall have an end dam at each end, not less than the datasheet height, formed and sealed against the flashing's back leg.

+### Sill pan flashing shall be continuous below the rough sill, lapped over the water-resistive barrier below, and turned up at the back and at both ends in the configuration indicated in the datasheet.

+### The sill pan back leg shall be not less than the datasheet height.

+### Sill pan flashing shall be installed before the window or door unit is set.

+### A head flashing without end dams discharges off its own ends into the wall cavity, which is the same result as having no head flashing at the jambs. A pan retrofitted after the unit is set cannot be turned up behind the frame, so it collects water it has no way to release. {note}

+# Gutters, Downspouts, and Scuppers {toc}

+## Gutter Profile, Sizing, and Slope {toc}

+```datasheet

+label: Gutter Profile

+type: radio

+options:

+ - "K-style ogee gutter"

+ - "Half-round gutter"

+ - "Box gutter"

+ - "Built-in gutter set within the roof edge"

+ - "Fascia-integrated gutter"

+```

+```datasheet

+label: Gutter Cross-Section and Outlet Sizing

+type: text

+drawing_ref: "roof drainage calculation"

+default: deferred

+```

+```datasheet

+label: Gutter Slope to the Outlet

+type: range

+unit: 'in/ft'

+min: 0

+max: 0.5

+step: 0.0625

+default: 0.125

+```

+```datasheet

+label: Gutter Hanger Maximum Spacing

+type: range

+unit: 'in o.c.'

+min: 12

+max: 48

+setpoints: [12, 16, 18, 24, 30, 32, 36, 48]

+default: 32

+```

+### Gutter cross-section, front and back heights, outlet size, and outlet spacing shall be established by the Engineer of Record from a roof drainage calculation using the contributory roof area and the design rainfall intensity required by the building code, and shall be as indicated in the datasheet.

+### The Contractor shall confirm the fabricated gutter cross-section against that calculation before releasing gutters for fabrication.

+### Gutters shall be sloped to the outlets at not less than the rate indicated in the datasheet.

+### Slope moves standing water to the outlet, which limits the residence time of debris, ice, and dissolved salts against the gutter's seams. At zero slope a gutter still drains, but only through the hydraulic gradient of the water itself, so construction tolerance and deflection between hangers set where the water actually stands. Visible slope against a level fascia line is the cost of a steeper rate on a long run. {note}

+### Gutters shall be supported at not more than the datasheet hanger spacing.

+### Hangers shall be of a metal compatible with the gutter and shall engage the outer rim from above.

+### Hangers shall not penetrate the bottom or inner face of the gutter.

+### Hangers shall be designed for the weight of the gutter filled to the overflow line, plus the snow and ice load determined for the project.

+## Gutter and Downspout Joinery {toc}

+```datasheet

+label: Gutter Running Joint Method

+type: radio

+options:

+ - "Soldered lap joint"

+ - "Welded lap joint"

+ - "Lapped joint sealed with concealed tape and a tooled bead"

+ - "Slip joint with a concealed backer plate at expansion joints and sealed laps between"

+```

+```datasheet

+label: Minimum Downspout Lap at Joints

+type: range

+unit: in

+min: 0.5

+max: 4

+setpoints: [0.5, 1, 1.5, 2, 3, 4]

+default: 1

+```

+```datasheet

+label: Downspout Strap Maximum Spacing

+type: range

+unit: ft

+min: 3

+max: 15

+setpoints: [3, 4, 5, 6, 8, 10, 12, 15]

+default: 10

+```

+### Gutter running joints shall be made by the method indicated in the datasheet, and the method shall be one the selected gutter metal accepts.

+### Gutter end caps shall be of the gutter metal, formed to the gutter profile, and joined to the gutter by the same method as the running joints.

+### Gutter expansion joints shall be provided at not more than the expansion joint spacing indicated in this standard for the gutter metal.

+### Downspout joints shall lap in the direction of flow, upper piece outside, by not less than the datasheet lap.

+### Downspouts shall be anchored to the wall at not more than the datasheet strap spacing, with straps of the downspout metal or a compatible metal not less noble than it.

+### Downspouts shall discharge to the collection point shown in the Contract Documents, [[drawing: as indicated on the contract documents]].

+### Downspout discharge at a below-grade outlet shall be coordinated with [[sync/below-grade-waterproofing]].

+## Scuppers, Conductor Heads, and Overflow {toc}

+```datasheet

+label: Through-Wall Scupper Construction

+type: radio

+options:

+ - "Formed metal sleeve with soldered or welded corners"

+ - "Formed metal sleeve with sealed mechanical corners"

+ - "Formed metal sleeve with an integral flange lapped by the roof membrane"

+ - "Not applicable because the roof edge has no through-wall scupper"

+```

+```datasheet

+label: Secondary Drainage Provision Served by This Scope

+type: radio

+options:

+ - "Overflow scuppers through the parapet"

+ - "Overflow conductor heads with an overflow lip"

+ - "Open roof edge providing secondary drainage without a parapet"

+ - "Not applicable because secondary drainage is provided by piped overflow drains"

+```

+### Through-wall scupper sleeves shall be fabricated by the method indicated in the datasheet, with a flange on the roof side lapped into the membrane assembly and a formed drip on the exterior face.

+### Scupper sleeves shall be fabricated as single units where the wall thickness allows, without a joint within the wall.

+### Conductor heads shall be sized to receive the design flow from the scupper or transition piece serving them, formed of the metal indicated for gutters and downspouts, and provided with an overflow lip on the open face that discharges outward.

+### The secondary drainage provision indicated in the datasheet shall be coordinated with the roof drainage design, and the elevation of every overflow opening shall be verified in the field before the sleeve is fabricated.

+# Expansion Joint Covers at Walls and Parapets {toc}

+## A building expansion joint separates structures that move independently, and it crosses the envelope at the wall, at the parapet, and onto the roof. The cover has to accommodate that movement and stay weathertight through the full range, and the transitions between planes are where it usually does not. {note}

+```datasheet

+label: Wall Expansion Joint Cover Type

+type: radio

+options:

+ - "Manufactured cover assembly with a preformed bellows and metal trim"

+ - "Shop-fabricated metal cover over an elastomeric bellows"

+ - "Composite metal and membrane cover"

+ - "Formed metal cover with a concealed slip joint"

+```

+```datasheet

+label: Design Movement at the Building Expansion Joint

+type: text

+drawing_ref: "structural drawings"

+default: deferred

+```

+## The expansion joint cover shall accommodate the design movement indicated in the datasheet without loss of weathertightness at either extreme of travel.

+## The sheet metal portion of the cover shall be of the metal indicated for wall flashing in this standard and shall be lapped or sealed to adjacent flashing so that water on the wall drainage plane is carried past the joint.

+## The cover shall run continuously from the wall plane onto the roof plane, and the transition shall be made without a break in the water-shedding path.

+## A cover that stops at the wall-to-roof transition and restarts on the roof leaves the corner of the joint - the point of largest combined movement - as an open seam behind two independent assemblies. {note}

+# Galvanic Separation of Dissimilar Metals {toc}

+## Separation Method and Extent {toc}

+```datasheet

+label: Dissimilar Metal Separation Method

+type: radio

+options:

+ - "Elastomeric gasket at the full contact area"

+ - "Non-curing sealant tape at the full contact area"

+ - "Polyethylene or polyolefin separation sheet"

+ - "Barrier coating applied to the contact face"

+ - "Non-metallic isolating washers and bushings at fasteners"

+```

+```datasheet

+label: Elastomeric Separation Gasket Minimum Thickness

+type: range

+unit: in

+min: 0.03

+max: 0.25

+setpoints: [0.03, 0.0625, 0.09375, 0.125, 0.1875, 0.25]

+default: 0.0625

+```

+### In the architectural galvanic series, running from most anodic to most cathodic, the order is zinc, aluminum, zinc-coated steel, carbon steel, lead, copper alloys, and stainless steel. The metal nearer the anodic end corrodes to protect the one nearer the cathodic end, and the rate depends on how much cathode area is coupled to how little anode area. {note}

+### Separation shall be provided wherever metals separated in the galvanic series are in direct contact, are coupled by water draining from one onto the other, or are connected through a shared fastener.

+### Separation shall be by the method indicated in the datasheet, installed across the full contact area without gaps.

+### Elastomeric separation gaskets shall be not thinner than the datasheet thickness.

+### Copper and copper alloy surfaces shall not drain onto aluminum, architectural zinc, zinc-coated steel, or carbon steel unless a continuous separation layer intercepts the runoff.

+### Zinc-coated steel and architectural zinc shall be separated from fresh mortar, fresh concrete, and copper-bearing runoff.

+### Aluminum shall be separated from fresh mortar, fresh concrete, and copper-bearing preservative-treated lumber.

+### Stainless steel fasteners through aluminum, zinc-coated steel, or architectural zinc shall carry a bonded sealing washer at the penetration.

+### Where a historically coated product such as lead-coated copper, tin-zinc coated copper, or terne-coated stainless steel is used, the Contractor shall obtain the producer's written compatibility requirements for every metal it will contact and shall submit them before fabrication.

+# Installation Sequencing and Substrate Acceptance {toc}

+## Sequence With the Roofing and Wall Trades {toc}

+### The sheet metal scope interleaves with the roofing scope at every roof-to-wall, roof-to-curb, and roof-edge interface, and with the wall scope at every flashing that a cladding material laps. {note}

+### The installation sequence shall follow the order below unless the pre-installation conference establishes a different order in writing for a specific condition:

+- Wood nailers and blocking at roof edges and parapet tops are installed and inspected before the roofing membrane.

+- The roofing Contractor installs the membrane field, the base flashings up the inside face of the parapet, and any edge components furnished as part of a warranted roof assembly.

+- Base flashings are completed and probed before counterflashings, copings, gravel stops, and fasciae are set over them.

+- Wall flashings are installed before the cladding that laps them, and gutters, downspouts, and trim follow the cladding.

+### The pre-installation conference shall record any condition where this order is altered, together with the reason and the responsible trade for each affected piece.

+### Where a coping or edge component is furnished under a cladding or panel scope, the interface between that piece and the sheet metal in this scope shall be detailed on the sheet metal shop drawings.

+## Substrate Acceptance {toc}

+### The installer shall inspect every substrate before installing sheet metal over it and shall verify that nailers are fastened, of the specified dimension and treatment, and at the correct elevation and width; that membrane base flashings are fully adhered and probed where they will be lapped; that masonry is at the dimensions shown with reglets cut clean to the specified depth; and that supporting framing for gutters and conductor heads is in place at the correct elevation.

+### Deficient substrate conditions shall be reported to the General Contractor in writing before work proceeds in that area.

+### Sheet metal shall not be installed over a non-conforming substrate.

+### Where the parties disagree whether a substrate condition is conforming, the Engineer of Record shall make the initial determination.

+### The cost of correcting a substrate condition reported in writing before installation shall be borne by the trade responsible for the substrate; the cost of removing and reinstalling sheet metal set over a condition that was not reported shall be borne by the sheet metal Contractor.

+## Field Cutting and Fitting {toc}

+### Field cutting shall be limited to end conditions, penetrations, and irregular corners that could not be dimensioned before adjacent construction was complete.

+### Field cuts shall be made with snips, hand shears, or a powered nibbler or shear that does not heat the metal.

+### Abrasive cutting wheels and abrasive saws shall not be used on coated or polished sheet metal.

+### Field-cut edges shall be deburred and shall receive the touch-up treatment specified for cut edges.

+# Field Testing and Inspection {toc}

+## Water Testing of Completed Flashings {toc}

+```datasheet

+label: Field Water Test of Completed Wall Flashings

+type: radio

+options:

+ - "First-of-type test on each flashing type before that type is produced in quantity"

+ - "Test at locations selected by the Engineer of Record during construction"

+ - "Test on a percentage of installed locations selected at random"

+ - "Not required"

+```

+```datasheet

+label: Water Test Spray Duration at Each Test Location

+type: range

+unit: minutes

+min: 5

+max: 60

+setpoints: [5, 10, 15, 20, 30, 45, 60]

+default: 15

+```

+```datasheet

+label: Proportion of Installed Locations Tested Where Random Testing Is Selected

+type: range

+unit: '%'

+min: 0

+max: 25

+setpoints: [0, 1, 2, 5, 10, 15, 25]

+default: 5

+```

+### Field water testing shall be performed at the frequency indicated in the datasheet, using a spray applied in accordance with AAMA 501.2 or an equivalent method the Engineer of Record accepts.

+### Each test location shall be sprayed for not less than the datasheet duration.

+### The interior side of each test location shall be observed continuously during the test and for fifteen minutes after the spray stops.

+### Water appearing on the interior side shall be cause for rejection of that location, and the cause shall be identified before the location is repaired.

+### The Contractor shall bear the cost of retesting a location that failed, and of testing the additional locations the Engineer of Record selects following a failure.

+## Inspection at Substantial Completion {toc}

+### The sheet metal work shall be jointly inspected at substantial completion by the Contractor, the Engineer of Record, and the Owner's representative.

+### The inspection shall verify that every piece is in its final position; that joints are formed and sealed as detailed; that no cured sealant bridges the moving portion of an expansion joint; that roof-edge metal matches the tested assembly in profile, cleat, fastener type, and fastener spacing; that flashings lap and shed water in the design direction; that gutters are sloped and clear; that downspouts are anchored and discharge as detailed; that dissimilar-metal separation is in place; and that finished surfaces are clean and undamaged.

+### Deficiencies identified at the inspection shall be corrected before the Contractor's warranty period begins.

+# Delivery, Storage, and Handling {toc}

+## Protection of Coil, Sheet, and Formed Pieces {toc}

+```datasheet

+label: Maximum Time Protective Film May Remain on Installed Metal

+type: range

+unit: days

+min: 30

+max: 180

+setpoints: [30, 45, 60, 90, 120, 180]

+default: 90

+```

+### Coil, sheet, and formed pieces shall be stored on edge or on spacers, off the ground, under cover, in a dry and ventilated location.

+### Pieces shall not be stacked flat with weight bearing on the finished face.

+### Water shall not be allowed to stand between stacked sheets or nested pieces.

+### Protective film shall remain in place through fabrication and installation and shall be removed at substantial completion, and in no case later than the datasheet duration after installation.

+### The Contractor shall confirm the film manufacturer's maximum exposure period and shall report to the Engineer of Record where the construction schedule would exceed it.

+### Film left on a surface past its exposure limit bonds to the coating under ultraviolet exposure and heat, and comes off in fragments or takes coating with it. Water trapped between stacked sheets produces white corrosion on zinc-bearing coatings and staining on coil coatings that no cleaning method removes. {note}

+# Cleaning and Protection {toc}

+## Cleaning of Installed Sheet Metal {toc}

+### Installed sheet metal shall be cleaned at substantial completion of construction debris, sealant residue, mortar residue, and protective film.

+### Cleaning shall use potable water and a detergent with a pH between 5 and 9, applied with a soft cloth or sponge and rinsed with potable water.

+### Solvents, acidic cleaners, alkaline cleaners, abrasive cleaners, and abrasive pads shall not be used on coated or polished surfaces.

+### Mortar or grout contacting a coated surface shall be flushed off with water before it sets.

+### Cured mortar shall be removed mechanically with a plastic or wood scraper.

+### Acid washing of adjacent masonry shall not be performed until sheet metal in the wash path has been masked and protected.

+### Wet mortar on a coil coating etches the film while it cures, so a smear removed the next morning leaves a permanent mark even when the mortar itself comes away cleanly. The time window is minutes, not hours. {note}

+# Warranty {toc}

+## Contractor Workmanship Warranty {toc}

+```datasheet

+label: Contractor Workmanship Warranty Term

+type: range

+unit: years

+min: 1

+max: 10

+setpoints: [1, 2, 3, 5, 10]

+default: 2

+```

+### The Contractor shall provide a written workmanship warranty for the term indicated in the datasheet, running from the date of substantial completion.

+### The warranty shall cover defects in fabrication, joinery, anchorage, and installation, including water entry at sheet metal joints and displacement under the design wind pressure.

+### The Contractor shall bear the cost of repair, of access to the repair location, and of repairing collateral damage caused by the defect or by the repair.

+### Where a warranted repair is made, the repaired work shall carry a warranty for a full term from the date of the repair, or for the remainder of the original term, whichever is longer.

+### The Contractor's warranty is in addition to the finish manufacturer's warranty and does not replace it.

+## Finish Manufacturer Warranty {toc}

+```datasheet

+label: Finish Warranty Term for Film Integrity

+type: range

+unit: years

+min: 5

+max: 40

+setpoints: [5, 10, 15, 20, 25, 30, 35, 40]

+```

+```datasheet

+label: Finish Warranty Term for Color Change and Chalk

+type: range

+unit: years

+min: 5

+max: 40

+setpoints: [5, 10, 15, 20, 25, 30, 35, 40]

+```

+```datasheet

+label: Maximum Color Change Over the Warranty Term

+type: range

+unit: 'ΔE units'

+min: 2

+max: 10

+setpoints: [2, 3, 4, 5, 6, 8, 10]

+default: 5

+```

+```datasheet

+label: Minimum Chalk Rating to ASTM D4214 at the End of the Warranty Term

+type: select

+options:

+ - "No. 4"

+ - "No. 6"

+ - "No. 8"

+default: "No. 8"

+```

+### The finish manufacturer shall provide a written warranty for the terms indicated in the datasheet, covering film integrity, color change, and chalk on the specified coating and color.

+### Color change over the warranty term shall not exceed the datasheet limit, measured to ASTM D2244 on a cleaned surface compared against an unexposed retained sample.

+### Chalk at the end of the warranty term shall be not less than the datasheet rating when evaluated to ASTM D4214.

+### The Contractor shall identify any project condition that falls within an exclusion in the finish manufacturer's warranty, and shall obtain the manufacturer's written position on that condition before the coating is ordered.

+### Marine spray, industrial fallout, agricultural ammonia, standing water, and chemical exposure are the exclusions that most often apply to a real site, and a coating ordered without checking them can arrive with a warranty that excludes the very exposure it was selected for. {note}

+## Roof-Edge Assembly Warranty {toc}

+### Where roof-edge metal is furnished as part of a warranted membrane roof assembly, the Contractor shall confirm in writing that the membrane manufacturer's warranty covers the edge metal on the same terms as the membrane.

+### Where roof-edge metal is furnished by an edge system manufacturer under its own warranty, the Contractor shall obtain that warranty and submit it at closeout.

+### The Contractor shall confirm before the edge product is ordered that the product is accepted by the membrane manufacturer for use with the warranted assembly.

+# Spare Materials {toc}

+```datasheet

+label: Touch-Up Material Delivered to the Owner per Specified Color

+type: range

+unit: quarts

+min: 0

+max: 8

+setpoints: [0, 1, 2, 4, 6, 8]

+default: 2

+```

+```datasheet

+label: Spare Formed Trim Delivered as a Proportion of Installed Length

+type: range

+unit: '%'

+min: 0

+max: 10

+setpoints: [0, 1, 2, 3, 5, 10]

+```

+```datasheet

+label: Spare Components Delivered to the Owner

+type: checkbox

+options:

+ - "Touch-up material in each specified color"

+ - "Spare formed trim in each specified profile"

+ - "Spare gutter hangers and downspout straps"

+ - "Spare cleat stock in each metal and thickness"

+ - "Spare sealant in each specified chemistry and color"

+default:

+ - "Touch-up material in each specified color"

+ - "Spare gutter hangers and downspout straps"

+```

+## The Contractor shall deliver the spare components indicated in the datasheet to the Owner at substantial completion.

+## Spare material shall be from the same production lot as the installed work wherever the lot remains available.

+## Spare material shall be delivered in sealed, labeled containers or wrapped bundles identifying the metal, thickness, finish system, color, and lot.

+## The Contractor shall obtain the Owner's written receipt for spare material delivered.

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