+---
+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
+
+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. 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. The SMACNA manual is the foundational industry reference for this work; this standard is intended to be read together with SMACNA's current edition and does not duplicate the geometric pattern details that the SMACNA manual already provides.
+
+Sheet metal flashing is interface work. Most pieces in this scope live at the seam between two other systems: roof and wall, wall and window, parapet and roof, expansion joint between two structural bays. 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. 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. The Contractor shall verify dimensions and substrate conditions before fabrication and 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. IBC Section 1504.5 requires that low-slope roof-edge metal be tested and labeled per ANSI/SPRI ES-1, and 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. ES-1 compliance is verified by the labeled product; copings or edge metal that are field-fabricated on site without an ES-1 listing for the as-built profile and securement are not code-compliant for low-slope roofs and 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 are nonetheless governed by 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 requires trained operators; welding of aluminum and stainless steel requires qualified welders; and brake-formed shop work in heavier gauges of steel and stainless requires 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
+
+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. Where conflict exists between referenced standards, the more stringent requirement governs unless the Designer of Record directs otherwise in writing.
+
+| 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 |
+
+# Submittals
+
+## Action Submittals
+
+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. 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.
+
+- 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: 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)"
+```
+
+## Closeout Submittals
+
+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
+
+# Quality Assurance
+
+## Fabricator Qualifications
+
+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, and 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
+
+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, and 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
+
+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 must be set before coping installation, which through-wall flashings must be set 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
+
+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
+
+## Material Selection — Principles
+
+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. 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. The Designer of Record shall establish the metal type for each piece in the scope, and 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.
+
+```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"
+```
+
+## Galvanized Steel — ASTM A653
+
+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. Cut edges of galvanized sheet are inherently exposed; cathodic protection from the adjacent zinc coating mitigates edge corrosion in service but the Contractor shall avoid leaving exposed cut edges in locations where water collects. 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 galvanized (unpainted, mill finish) exhibits a "spangle" pattern that weathers to a uniform gray over several years; on prominent exterior surfaces, the visual progression of mill galvanized is generally not desirable and a prepainted finish is preferred.
+
+```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"
+```
+
+The SMACNA Architectural Sheet Metal Manual provides recommended gauge tables keyed to piece type, span between joints or supports, and metal alloy. Specifying a heavier gauge than SMACNA recommends increases stiffness and dent resistance but increases brake-forming difficulty and cost. Specifying a lighter gauge than SMACNA recommends can result in oil-canning (visible waviness in flat fields between stiffeners), seam distortion, and reduced longevity. The Contractor shall follow the SMACNA gauge tables unless the contract documents specify a heavier gauge.
+
+## Galvalume (55% Al-Zn) — ASTM A792
+
+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, particularly in industrial and chloride-exposed inland environments; however, Galvalume 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. 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.
+
+```datasheet
+label: Galvalume Coating Designation
+type: radio
+options:
+ - "AZ50 (standard exterior architectural)"
+ - "AZ55 (extended exposure, corrosive environments)"
+default: "AZ50 (standard exterior architectural)"
+```
+
+## Aluminum — ASTM B209
+
+Aluminum sheet for architectural flashing and trim shall conform to ASTM B209/B209M. Common alloys for formed sheet are 3105-H14 (general-purpose, good formability) and 5005-H14 (improved anodizing response; preferred substrate for anodized finishes). For copings, fasciae, and trim that are not anodized, alloy 3003-H14 is also acceptable. Aluminum is light, corrosion-resistant in most atmospheric environments, and the standard substrate for prefinished PVDF coil-coated trim on commercial buildings. Aluminum is not appropriate 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-metals section below is required.
+
+```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"
+```
+
+## Stainless Steel — ASTM A240
+
+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 is No. 2B (cold-rolled, annealed, smooth, low-reflectivity) for general flashing and trim; No. 4 (brushed, satin) is appropriate 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 than other metals to avoid cracking, and (in heavier gauges) requires welding rather than soldering at joints. Stainless is also the most expensive of the common architectural metals; its use is generally restricted to high-exposure or high-durability applications where the additional cost is justified.
+
+```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)"
+```
+
+## Copper — ASTM B370
+
+Copper sheet for architectural sheet metal shall conform to ASTM B370, cold-rolled and tempered, with weight specified in ounces per square foot. The standard architectural weights are 16 oz/sf (approximately 0.0216 in thick), 20 oz/sf (0.0270 in), and 24 oz/sf (0.0323 in). Copper is the historic premium architectural metal and weathers from new bright copper through brown to a stable patina (green-blue or brown-black, depending on environment) over a period of years to decades. The patinated surface is itself the corrosion-protection layer; the visual progression is part of the design intent of copper, and the Owner shall be informed of the weathering trajectory before specifying copper for prominent surfaces.
+
+Copper runoff stains adjacent porous materials (limestone, concrete, painted aluminum) green or blue-black. Where copper is installed above a porous surface 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) require more heat input and slower work than 16 oz/sf and shall be performed by a soldering operator experienced in the heavier weight.
+
+```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"
+```
+
+## Zinc — ASTM B69
+
+Architectural zinc sheet (rolled zinc-copper-titanium alloy) shall conform to ASTM B69. Zinc forms a self-healing carbonate patina in atmospheric exposure that protects the underlying metal and gives architectural zinc its characteristic blue-gray appearance. Standard architectural thicknesses are 0.7 mm, 0.8 mm, and 1.0 mm. Zinc has very low tolerance for stagnant moisture on the underside (white corrosion is a rapidly progressing failure mode); all zinc sheet metal shall be installed with a ventilated underside per the zinc manufacturer's published details, and shall not be installed over a moisture-trapping underlayment. Zinc is also incompatible with direct contact with copper, copper-bearing salts, and oak or chestnut tannins, and with continuous contact with wet alkaline materials (fresh concrete, mortar).
+
+```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)"
+```
+
+# Finishes
+
+## Prepainted Coil — PVDF and SMP
+
+Prefinished coil-coated steel and aluminum sheet for architectural sheet metal trim shall be coated with one of the following systems, selected by the Designer of Record based on service life, visual exposure, and budget. PVDF (polyvinylidene fluoride, commonly trade-named Kynar 500 and Hylar 5000) is the premium architectural coating; full-strength 70% PVDF resin systems conform to AAMA 2605 and provide ten-year color retention and chalk performance that is the industry standard for prominent visible exterior architectural metal. 50% PVDF / SMP-PVDF blend systems conform to AAMA 2604 and provide significantly better performance than commercial polyester at a lower cost than full-strength PVDF; AAMA 2604 is the appropriate finish for general commercial trim where the visible exposure is moderate. Commercial polyester (AAMA 2603) is appropriate only for low-exposure, low-visibility applications or for interior trim; it shall not be specified for prominent exterior architectural surfaces with long service-life expectations.
+
+```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: true
+default: "Per Designer of Record — see finish schedule on drawings"
+```
+
+Custom colors are available from all major coil-coating manufacturers, typically with a 4,000 to 8,000 lb minimum order. Stock colors are available in much smaller quantities and from local distribution. The Contractor shall confirm the coil-coating order requirements and lead time at the time of submittal; a custom color with an 8-week coil lead time can become the critical path of the sheet metal scope and shall not be discovered late in the construction schedule.
+
+## Anodized Aluminum — AAMA 611
+
+Anodized aluminum finishes shall conform to AAMA 611. Class I anodizing (minimum 0.7 mil coating thickness) is appropriate for exterior architectural use and provides long service life with stable color. Class II (minimum 0.4 mil) is appropriate for interior or low-exposure exterior use only. Anodized finishes are inherently variable in color across coils and lots; the Contractor shall confirm acceptable color variation tolerance with the Designer of Record before ordering, and shall order all anodized aluminum for a single building elevation from a single coil run where uniformity is critical.
+
+```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)"
+```
+
+## Mill and Natural Finishes
+
+Mill galvanized, mill stainless, mill copper, and mill zinc each weather to a stable natural patina over time. 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.
+
+## Field Touch-Up
+
+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 of a coping cap that are concealed by the bend, fastener heads beneath a sealant joint). Field-painted patches on visible surfaces will weather differently than the surrounding factory finish and shall be avoided; pieces with visible damage on prominent surfaces shall be replaced, not touched up.
+
+# Accessory Materials
+
+## Fasteners
+
+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 (typically the case with stainless sheet, where stainless fasteners are standard), the fastener material shall be at least as noble as the sheet metal — never less noble — so that any galvanic current attacks the fastener mass minimally and not the sheet.
+
+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 (galvanic corrosion of the fastener and staining of the copper). Zinc sheet shall be fastened with stainless steel fasteners.
+
+```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)"
+```
+
+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.
+
+## Sealants
+
+Sealants for architectural sheet metal joints shall be selected by the type of joint and the expected movement. Three sealant categories are used:
+
+- **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.
+
+```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)"
+```
+
+```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
+
+A self-adhering, polymer-modified bituminous underlayment, conforming to ASTM D1970 for ice-dam protection products, shall be installed on the substrate beneath all sheet metal flashing surfaces that overlie a structural deck, wall sheathing, or wood blocking. The underlayment provides a secondary water seal beneath the metal and protects the substrate from any water that migrates past the metal at fastener penetrations, joints, or cleats. 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 (as at gravel stops and copings that overlap the membrane base flashing), the membrane itself serves as the secondary water seal and a separate underlayment beneath the metal is not required; the metal cleat or hook strip is fastened through the membrane base flashing into structural blocking, and the membrane manufacturer's published detail governs.
+
+```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"
+```
+
+## Cleats and Hook Strips
+
+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 the piece against wind uplift without exposed fasteners through the visible face. Cleats are the primary wind-uplift securement for copings, gravel stops, fasciae, and gutters; their material, gauge, and fastener spacing are integral to the ANSI/SPRI ES-1 wind classification of the assembly. 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.
+
+Continuous cleats are preferred over intermittent (clip) cleats for prominent visible work because they distribute the engagement uniformly along the hem and eliminate the localized stress that can show as a hem distortion at clip locations. Intermittent cleats are acceptable in concealed locations and where the ES-1 test has been performed on the intermittent configuration; an intermittent cleat shall not be substituted for a continuous cleat in an ES-1-listed assembly without revised testing.
+
+```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)"
+```
+
+# Fabrication
+
+## General Principles
+
+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. Shop forming under controlled conditions produces straighter pieces, more uniform bends, and less risk of finish damage than field forming. 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 typically tolerates an inside-bend radius equal to 1 to 1.5 times the metal thickness 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; sharp edges concentrate corrosion initiation, create cuts for installers, and produce a visible irregularity on prominent edges. Edges that will be exposed in service (the open end of a hem, the lower edge of a gravel stop, the upper edge of a counterflashing where it is not capped) shall be hemmed back on themselves so that no raw edge is exposed.
+
+## Joints
+
+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. The joint type for each piece shall be specified on the shop drawings and shall match the SMACNA detail being followed.
+
+**Lapped joints with sealant** are the standard joinery for short pieces of counterflashing, head and sill flashings, and similar work. The minimum lap shall be 2 inches in the direction of water flow. The lap shall include a continuous butyl tape concealed within the lap and a continuous bead of sealant at the upstream edge of the lap; the sealant shall be tooled to a clean fillet at the metal surface.
+
+**Standing seams** are the joinery of choice for long-run gutters, copings, and fasciae where a clean, drained joint without exposed sealant is desired. A double-lock standing seam at a coping or fascia joint creates a watertight, expansion-tolerant joint without sealant if formed correctly. Standing seams shall be a minimum 1 inch tall, hand-sealed (or machine-seamed where the machine is appropriate to the gauge and metal). Double-lock seams are preferred over single-lock for permanent installations.
+
+**Slip-and-lock expansion joints** (also called S-locks or backer-plate joints) are used at expansion joints between pieces of coping, gravel stop, and fascia. The joint consists of a backer plate (a separate piece of metal 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 over the backer plate as thermal movement occurs. The slip-and-lock joint shall be sealed on the upstream side with butyl tape; 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.
+
+```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"
+```
+
+## Cleats
+
+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; 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
+
+Hems are the folded-back edges of sheet metal that provide stiffness, eliminate exposed cut edges, and engage cleats. The standard architectural hem is a 1/2-inch single hem, formed by bending the sheet 180 degrees back on itself. Double hems (folded twice) are 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.
+
+```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)"
+```
+
+## Expansion Joint Provisions
+
+All metals expand and contract with temperature; failure to accommodate this movement results in buckling in hot weather, joint tearing in cold weather, and fastener pull-through over many thermal cycles. The expansion joint spacing in running sheet metal shall be designed for the metal's coefficient of thermal expansion and the expected temperature range. Approximate maximum running lengths between expansion joints, for prefinished coil exposed to direct sun on a low-slope roof in temperate climates, are:
+
+- 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
+
+These are general guidelines; the SMACNA Architectural Sheet Metal Manual provides specific tables keyed to climate zone and surface color (darker surfaces reach higher peak temperatures and therefore require closer joint spacing). 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 as described above. 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.
+
+```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"
+```
+
+## Soldering and Welding
+
+Soldering of copper and lead-coated copper joints shall use lead-free solder per current code requirements; rosin flux shall be 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; voids in soldered seams shall be re-soldered. Soldering of copper greater than 16 oz/sf requires 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 are not soldered or welded in architectural sheet metal practice; joints in galvanized and aluminum sheet are 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
+
+## Compliance Requirement
+
+ANSI/SPRI/FM 4435/ES-1 establishes the wind-pressure resistance of metal edge systems used on low-slope roofs. The standard defines three test methods: RE-1 (horizontal displacement of the edge cover after wind pressure), RE-2 (vertical pull-out of the edge cover under wind uplift), and RE-3 (cyclic pressure simulating fluctuating wind). An ES-1 listing classifies the assembly by the pressure (psf) it resisted in the test. 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. 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 (this last path is rarely cost-effective compared to specifying an ES-1-listed product).
+
+```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: [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"
+```
+
+## Cleat and Fastener Pattern
+
+For ES-1-listed edge-metal assemblies, the cleat material, gauge, fastener type, fastener spacing, and substrate (typically a continuous wood nailer of a minimum thickness, pre-treated for the climate) are integral to the listing. 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; preservatives that release chloride or that are highly acidic shall be avoided where they are in contact with 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
+
+## Counterflashings at Membrane Roof Base Flashings
+
+Counterflashings are formed metal pieces that lap over the top edge of a membrane base flashing on a vertical surface, providing a watertight transition from the wall to the roof membrane. The counterflashing protects 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 protection that is mechanically removable for membrane re-roofing in the future.
+
+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 — counterflashings fastened directly to the wall face with exposed fasteners and a sealant joint at the top edge — are a lower-tier detail acceptable only on retrofits where reglet cutting is not feasible; surface-mounted counterflashings depend on the sealant joint for water exclusion and require periodic sealant replacement.
+
+```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"
+```
+
+The counterflashing shall lap over the top of the membrane base flashing by a minimum of 4 inches. The lap zone is not sealed (counterflashings are removable to allow future re-roofing), but the geometry of the lap 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.
+
+```datasheet
+label: Counterflashing Lap Over Membrane Base Flashing (minimum)
+type: select
+unit: in
+options:
+ - "3 in"
+ - "4 in"
+ - "6 in"
+default: "4 in"
+```
+
+## Through-Wall Flashings at Masonry
+
+Through-wall flashings are continuous flashings installed within masonry walls at the base of the wall, at floor lines, at heads and sills of openings, and at shelf angles, that intercept water that has penetrated the outer wythe of masonry and direct it back out at the wall face through weep openings. Through-wall flashings are not strictly sheet metal in modern construction (membrane through-wall flashings — self-adhering rubberized asphalt or composite stainless-and-membrane laminates — have largely replaced solid metal through-wall flashings); however, 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. Coordinate the through-wall flashing assembly 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
+
+Head flashings over wall openings (windows, doors, louvers) shall be continuous formed metal pieces that lap over the top of the window or louver frame and turn up at the back behind the wall water-resistive barrier (WRB) so that any 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 flashings (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 at 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.
+
+```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"
+```
+
+# Gutters and Downspouts
+
+## Gutter Design Basis
+
+Gutter sizing — the cross-sectional area, the front and back heights, the downspout outlet size and spacing — is established by the roof drainage calculation, which is the responsibility of the Designer of Record. Gutter sizing shall be 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 slope of the gutter. SMACNA provides gutter sizing tables; the gutter cross-section shall be confirmed against the calculated flow before fabrication. Under-sized gutters that overflow during a design storm direct water onto the wall below, leading to wall water-intrusion problems that are commonly misdiagnosed as wall-construction failures.
+
+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 do not drain reliably (small construction tolerances result in localized low spots and ponding) and shall not be specified. Gutter expansion joints shall be located at maximum 40-ft spacing for steel and stainless, 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]].
+
+```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: true
+default: "Per Designer of Record roof drainage calculation — see civil and roof drawings"
+```
+
+## Gutter Joinery
+
+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. Soldered copper gutters provide a watertight, monolithic gutter that does not depend on sealant for water exclusion; aluminum and steel gutters that cannot be soldered depend on butyl tape and sealant at lapped joints and shall be detailed accordingly. Lapped-and-sealed gutter joints shall be in the direction of flow (upstream piece outside, downstream piece inside) and shall be 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). Field-cut gutter end caps from a flat sheet without forming to match the profile are a common installation error that results in a poor fit, multiple sealant beads, and a leak source.
+
+## Gutter Hangers and Brackets
+
+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; in cold climates, ice-loaded gutters can weigh several times the empty gutter weight, and undersized hangers will fail in the first ice cycle.
+
+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 any water in the gutter does not encounter a fastener penetration.
+
+```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)"
+```
+
+## Downspouts and Conductor Heads
+
+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. Downspouts that discharge to a horizontal grade-level surface without a splash block or routing erode the soil at the discharge point and route water back toward the foundation. Coordinate downspout discharge with [[sync/below-grade-waterproofing]] foundation drainage at any below-grade outlet condition.
+
+```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."
+```
+
+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
+
+## Function and Design Basis
+
+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. 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. Level copings retain water; sloped copings shed water reliably. The slope direction shall be toward the roof side so that water leaving the coping falls onto the membrane (which can handle it) rather than onto the wall face (which over time accumulates staining and increases wall water-intrusion risk).
+
+```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 Joinery and Expansion
+
+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. Lapped joints shall be 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.
+
+```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)"
+```
+
+# Wall Expansion Joints and Expansion Joint Covers
+
+Building expansion joints — joints that allow the structural framing on either side to move independently — penetrate the building envelope at the wall and roof. 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. Expansion-joint covers vary widely in design; common types include preformed bellows of EPDM or silicone retained by formed metal trim pieces on each side of the joint, formed-metal covers with a flexible inner liner, and proprietary engineered expansion-joint products that combine the sealing element and the trim into a unitized assembly.
+
+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; a discontinuous expansion-joint cover at the wall-roof transition is a common leak source and is among the most difficult details in the sheet metal scope.
+
+```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: true
+default: "Per Structural Engineer of Record — see structural drawings"
+```
+
+# Dissimilar Metal Isolation
+
+## Galvanic Compatibility
+
+Dissimilar metals in direct or water-coupled electrical contact form a galvanic cell that drives accelerated corrosion of the less noble (more anodic) metal. The standard galvanic series for architectural metals, ordered from most anodic (least noble, sacrificed first) to most cathodic (most noble, protected), is approximately: zinc, aluminum, galvanized steel, mild steel, copper alloys, stainless steel. Aluminum, zinc, and galvanized steel are the metals most commonly corroded by galvanic action in architectural sheet metal applications; copper and stainless are the metals most commonly responsible for driving corrosion of others.
+
+Galvanic isolation shall be provided wherever metals at significantly different points in the galvanic series will be in direct contact, in water-coupled proximity (water from one metal running onto another), or in shared-fastener contact. Isolation is achieved by separating the metals with a barrier of polymer (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 (so that the fastener does not become the galvanic source).
+
+```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"
+```
+
+## Specific Contact Conditions
+
+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 have specific compatibility requirements that shall be 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. Fresh concrete and mortar produce a high-pH water that dissolves the aluminum oxide protective layer and continues into the base metal until the concrete cures; once cured, the chemistry stabilizes, but unmitigated contact during the cure period leaves pitting and discoloration. ACQ-treated lumber is acidic and contains soluble copper, both of which attack aluminum; isolation between an aluminum cleat and an ACQ-treated wood nailer is required.
+
+Galvanized steel and zinc sheet are degraded by direct contact with fresh mortar and concrete (similar mechanism as aluminum) and by direct copper contact. Stainless steel is broadly compatible with all common architectural metals as the cathodic (protected) member of a couple, but stainless fasteners through aluminum, galvanized, or zinc sheet are still galvanic cells where the fastener is the cathode and the sheet is sacrificed; the small area ratio (small fastener, large sheet) generally limits corrosion to acceptable levels, but EPDM-washered fasteners are standard to seal the fastener penetration and reduce moisture coupling.
+
+# Installation Sequence
+
+## Coordination with the Roofing Trade
+
+The sheet metal scope is interleaved with the roofing scope at every roof-to-wall, roof-to-curb, and roof-edge interface. 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 (some single-source warranty programs include the edge metal), 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 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 is installed as part of the panel scope rather than the sheet metal scope).
+
+## Substrate Acceptance
+
+The sheet metal installer shall inspect all substrates before installation and shall not proceed until the substrate meets the following conditions: wood nailers shall be properly fastened, of the specified thickness and treatment, at the correct elevation and width; membrane base flashings shall be fully bonded and probed where they will be lapped by counterflashings or copings; masonry shall be at the correct dimension and reglet cuts shall be clean and to the specified depth; and structural framing supporting heavy pieces (gutters, conductor heads) shall be in place and at the correct elevation. Deficient substrates shall be reported to the General Contractor in writing; the sheet metal Contractor shall not proceed over a non-conforming substrate without correction.
+
+## Field Cutting and Fitting
+
+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
+
+## Storage and Handling
+
+Prefinished coil and panel shall be stored on edge, off the ground, under protective wrap or cover, in a dry location. 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; water trapped between panels of prefinished coil 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
+
+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; these damage the finish and the Owner will see the damage as the unprotected substrate weathers over time. 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
+
+Touch-up paint matching the coil finish shall be applied to all field-cut edges, fastener heads where exposed, 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
+
+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
+
+## Fabricator and Installer Warranty
+
+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.
+
+```datasheet
+label: Contractor Sheet Metal Workmanship Warranty Period (minimum)
+type: select
+unit: years
+options:
+ - "1 year"
+ - "2 years"
+ - "5 years"
+default: "2 years"
+```
+
+## Finish Manufacturer Warranty
+
+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 shorter — 20 years for similar metrics. The specific warranty terms vary by manufacturer; the Contractor shall submit the finish manufacturer's warranty form with the submittals.
+
+```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 finish warranty typically excludes damage from atmospheric contaminants beyond the coil-coating standard exposure assumptions (heavy industrial fallout, marine spray within 1,500 ft of salt water, agricultural ammonia exposure), damage from chemical exposure, damage from physical impact, and substrates outside the manufacturer's approved substrate list. Project conditions that match any exclusion shall be identified before submittal so that the finish system can be confirmed appropriate for the exposure.
+
+## Roof-Edge Assembly Warranty
+
+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; 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
+
+Architectural sheet metal generates a consistent set of field errors and RFIs. The following are among the most frequently encountered.
+
+**Field-fabricated coping or gravel stop on a low-slope roof.** Field-fabricated roof-edge metal without an ES-1 listing for the as-built profile is not IBC-compliant for low-slope roofs. The Contractor shall not field-fabricate roof-edge metal on a low-slope roof; ES-1-listed manufactured product or engineered profile is required.
+
+**Sealant bridging across expansion joints.** Sealant applied across a slip-and-lock expansion joint constrains thermal movement and will be torn open at the first significant temperature swing. Expansion joints shall be sealed only on the upstream side with butyl tape; the moving portion of the joint shall not be sealed.
+
+**Termination bar on a horizontal surface.** Termination bars used in membrane base-flashing scope are designed for vertical application; the sheet metal Contractor's 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 that project less than 1/2 inch and are not turned downward will conduct water back along the underside to the substrate, depositing the water at the substrate face rather than dripping clear. Drip edges shall project at least 1/2 inch and be turned downward at least 30 degrees from horizontal.
+
+**Missing head flashing end dams.** Head flashings without turned-up end dams allow water to run off the side of the flashing back into the wall cavity. Every head flashing shall have an end dam on each end, formed and sealed at the flashing's back leg.
+
+**Galvanized fasteners in copper or stainless sheet.** Galvanized fasteners in copper or stainless sheet form an aggressive galvanic couple in which the fastener corrodes rapidly, the fastener head fails within years, and rust staining tracks down the metal face. Fastener material shall always be at least as noble as the sheet, never less noble.
+
+**ACQ-treated nailer in contact with aluminum coping cleat.** Aluminum cleats fastened to ACQ-treated (alkaline copper quaternary) lumber corrode at the contact face within months in wet exposures. The aluminum-ACQ contact shall be isolated with a polymer barrier or a non-ACQ preservative shall be specified for the nailer.
+
+**Solder flux not cleaned after copper soldering.** Rosin flux residue left on soldered copper joints absorbs moisture and accelerates corrosion under the solder line, eventually breaking the solder bond. All flux residue shall be neutralized and washed off after the joint cools.
+
+**Coping pieces installed without a slope.** Level coping caps retain water along their length; standing water on a coping top accelerates finish degradation and increases the likelihood of water entry at any joint or fastener. Coping shall be installed with a minimum 1/4 inch per foot transverse slope, typically toward the roof side.
+
+**Gutter or downspout undersized for the contributory area.** Undersized gutters overflow during design storms and route water onto the wall below and the foundation. Gutter and downspout sizing is the Designer of Record's responsibility but is a frequent field RFI when the indicated size appears small for the contributory area. Sizing shall be confirmed against the SMACNA tables or a roof drainage calculation before fabrication.
+
+**Mortar smears on prefinished coil left to cure.** Mortar in contact with prefinished aluminum or Galvalume produces a permanent visual mark even after removal, because the alkaline contact bleaches the finish. Mortar smears shall be removed with water within minutes of contact, not at end of day.
+
+**Copper runoff onto aluminum, zinc, or galvanized below.** Copper above an aluminum, zinc, or galvanized component allows copper salts to wash onto the metal below, where they drive galvanic corrosion. 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.
+
+**Coil-coated panels stored flat with weight on top.** Storage flat with stacking pressure causes oil-canning, finish indentation, and edge damage along contact lines. Panels shall be stored on edge or otherwise unloaded during storage.
+
+**Coping cleat fastener pattern not matching ES-1 listing.** Substituting fastener type, spacing, or substrate from the ES-1-listed assembly voids the listing. The Contractor shall verify the as-installed cleat fastener pattern against the listing documentation in the submittal before closing in the work.