+---
+title: Gutters and Downspouts
+category: Building Envelope
+toc_depth: 3
+description: >
+ When to use: Exterior rainwater conveyance hung at or immediately below the
+ building eave - eave-hung gutters (K-style, half-round, box/built-in), leader
+ heads, downspouts, elbows, offsets, outlet tubes, strainers, splash blocks,
+ and grade or storm-connection terminations. Covers sloped-roof commercial,
+ institutional, industrial, multifamily, and residential-scale commercial
+ buildings, and flat-roof perimeter edge drainage where gutters replace
+ internal drains; in prefinished aluminum, galvanized steel, Galvalume, copper,
+ and zinc; seamless field-formed or shop-fabricated sections.
+ Not intended for: Internal roof drains, overflow drains, and below-deck storm
+ piping ([[sync/roof-drainage]]); roof scuppers ([[sync/roof-drainage]] and
+ [[sync/sheet-metal-flashing-and-trim]]); gravel stops, copings, and
+ non-gutter edge metal ([[sync/roof-specialties-and-copings]] and
+ [[sync/sheet-metal-flashing-and-trim]]); through-wall and embedded flashing
+ at gutter-to-wall junctions ([[sync/sheet-metal-flashing-and-trim]]); membrane
+ roofing field and perimeter edge details ([[sync/membrane-roofing]]);
+ underground storm sewer and site drainage beyond the building face (site
+ civil scope); in-gutter snow-melt heat cable ([[sync/snow-melt-systems]]);
+ and joint-sealant-primary work at end caps and miters
+ ([[sync/exterior-weather-sealants]]).
+---
+
+# Scope {toc}
+
+## This standard covers the design, material selection, fabrication, and installation of exterior rainwater conveyance attached to or immediately below the building eave, including eave-hung gutters, leader heads, downspouts, and their fittings and terminations. {note}
+
+## Gutters in this standard collect roof runoff at the eave and convey it to downspouts that discharge to grade or to a storm connection at the building face. The eave gutter is the point where roof drainage leaves the roof plane and enters a dedicated conveyance; everything upstream of that line is roofing and everything downstream of the building face is site civil work. {note}
+
+## Covered components include eave-hung gutters in K-style (ogee), half-round, and box/built-in (yankee) profiles; leader heads and conductor heads; round, rectangular, and corrugated downspouts; elbows, offsets, and outlet tubes; outlet strainers; splash blocks; and downspout extensions. {note}
+
+## Covered substrate materials are prefinished aluminum, galvanized steel, Galvalume (55% aluminum-zinc alloy-coated steel), copper, and zinc alloy, in both seamless field-formed and shop-fabricated sectional construction. {note}
+
+## Exclusions: the following are out of scope for this standard. {note}
+
+- Internal roof drains, primary drain bowls, overflow drains, and horizontal below-deck storm piping ([[sync/roof-drainage]])
+- Roof scuppers, whether through-wall or through-parapet ([[sync/roof-drainage]] and [[sync/sheet-metal-flashing-and-trim]])
+- Gravel stops, copings, and perimeter edge metal that do not form a gutter cross-section ([[sync/roof-specialties-and-copings]] and [[sync/sheet-metal-flashing-and-trim]])
+- Through-wall and embedded flashing at gutter-to-wall junctions ([[sync/sheet-metal-flashing-and-trim]])
+- Membrane roofing field and perimeter edge details ([[sync/membrane-roofing]])
+- Underground storm sewer piping and site drainage downstream of the building face (site civil scope)
+- In-gutter snow-melt heat cable ([[sync/snow-melt-systems]])
+- Work at end caps and miters where the primary scope is sealant ([[sync/exterior-weather-sealants]])
+
+# Referenced Standards {toc}
+
+## Equipment, materials, and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited.
+
+## Where referenced standards conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
+
+## Code-required sizing shall be based on the rainfall intensity adopted by the Authority Having Jurisdiction; where the construction documents and the adopted code specify different bases, the more conservative result shall govern.
+
+| Standard | Title |
+|----------|-------|
+| SMACNA Architectural Sheet Metal Manual | Architectural Sheet Metal Manual, Chapter 1: Roof Drainage |
+| ASTM B209 | Aluminum and Aluminum-Alloy Sheet and Plate |
+| 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 B370 | Copper Sheet and Strip for Building Construction |
+| ASTM A755/A755M | Steel Sheet, Metallic Coated and Prepainted by the Coil-Coating Process for Exterior Exposed Building Products |
+| AAMA 2604 | Voluntary Specification for High Performance Organic Coatings on Aluminum Extrusions and Panels |
+| AAMA 2605 | Voluntary Specification for Superior Performing Organic Coatings on Aluminum Extrusions and Panels |
+| IPC Section 1106 | International Plumbing Code, Size of Conductors, Leaders and Storm Drains |
+| IBC Section 1503 | International Building Code, Weather Protection |
+| IRC Section P2912 | International Residential Code, Roof Drains, Gutters and Downspouts |
+| ASCE 7 Chapter 8 | Minimum Design Loads and Associated Criteria for Buildings and Other Structures, Rain Loads |
+
+# Submittals {toc}
+
+## Action Submittals {toc}
+
+### The Contractor shall submit the following action submittals for review before fabrication:
+
+- Product data for each gutter profile, downspout, hanger, outlet, leader head, and accessory, identifying material, alloy or coating class, thickness, and finish.
+- Shop drawings showing gutter layout, slope, expansion joint locations, hanger spacing, outlet and downspout locations, miter and end-cap details, and connection to roofing and to discharge terminations.
+- Sizing calculations relating projected roof area, design rainfall intensity, gutter cross-section, and downspout count to the governing sizing basis (SMACNA tables or IPC Section 1106).
+- Color samples of the specified finish on the actual substrate, and a representative seamed and mitered corner sample for each gutter material.
+- Fabrication-method statement identifying which runs are field-formed seamless and which are shop-fabricated sectional, including joint method.
+
+```datasheet
+label: Action submittals required
+type: checkbox
+options:
+ - Product data (gutters, downspouts, hangers, outlets, accessories)
+ - Shop drawings (layout, slope, expansion joints, hangers, outlets)
+ - Sizing calculations (roof area, rainfall intensity, gutter/downspout sizing)
+ - Color and corner samples on actual substrate
+ - Fabrication-method statement (seamless vs. sectional)
+default:
+ - Product data (gutters, downspouts, hangers, outlets, accessories)
+ - Shop drawings (layout, slope, expansion joints, hangers, outlets)
+ - Sizing calculations (roof area, rainfall intensity, gutter/downspout sizing)
+ - Color and corner samples on actual substrate
+```
+
+## Informational Submittals {toc}
+
+### The Contractor shall submit the following informational submittals:
+
+- Manufacturer's coating warranty for prefinished products, stating resin system, film integrity, and color/chalk terms.
+- Installer qualification statement documenting prior seamless-gutter and architectural sheet metal experience.
+- Coordination record identifying the responsible party for each downspout discharge termination (splash block, underground connection, or dry well).
+
+```datasheet
+label: Informational submittals required
+type: checkbox
+options:
+ - Coating warranty documentation
+ - Installer qualification statement
+ - Discharge-termination coordination record
+default:
+ - Coating warranty documentation
+ - Discharge-termination coordination record
+```
+
+## Closeout Submittals {toc}
+
+### The Contractor shall submit the following closeout submittals before final acceptance:
+
+- Maintenance instructions covering cleaning intervals, debris removal, and finish care.
+- Executed material and coating warranties.
+- Record drawings showing final gutter layout, expansion joint locations, and downspout terminations as installed.
+
+```datasheet
+label: Closeout submittals required
+type: checkbox
+options:
+ - Maintenance instructions
+ - Executed warranties (material and coating)
+ - Record drawings (as-installed layout and terminations)
+default:
+ - Maintenance instructions
+ - Executed warranties (material and coating)
+ - Record drawings (as-installed layout and terminations)
+```
+
+# Quality Assurance {toc}
+
+## Sheet metal fabrication and installation shall conform to the applicable fabrication details and tolerances of the SMACNA Architectural Sheet Metal Manual. {note}
+
+## The installer shall have completed sheet metal gutter and downspout work of comparable scope, material, and profile on prior projects.
+
+## Seamless field-forming, soldered copper joints, and concealed-hanger layout each depend on craft skill that product data alone cannot assure. {note}
+
+## Gutter and downspout systems shall be installed by a single installer of record for the entire project.
+
+## The installer shall demonstrate prior experience with the specified gutter material and profile, including soldered joints where copper or zinc is specified.
+
+## A pre-installation conference shall be held to coordinate gutter slope, expansion joint locations, outlet and downspout positions, roofing terminations, and discharge connections.
+
+## Where the gutter material differs from adjacent metals at the roof edge, the contractor shall confirm galvanic compatibility before fabrication.
+
+## Dissimilar-metal contact is the most common cause of premature gutter failure. {note}
+
+## A representative mock-up of a gutter run with one outlet, one downspout, one expansion joint, and one mitered corner shall be erected and approved before production work begins on projects with exposed architectural sheet metal.
+
+# Environmental and Service Conditions {toc}
+
+## Rainfall intensity is the controlling environmental variable for sizing, and it must be drawn from the correct basis. SMACNA sizing tables use a 5-minute duration, 100-year return-period intensity, while IPC Section 1106 uses a 1-hour, 100-year rate; the 1-hour rate is substantially lower and will undersize a gutter against fast, high-intensity storms if used in place of the 5-minute basis. Local intensity data is taken from NOAA Atlas 14 for the project location. {note}
+
+## Gutters and downspouts shall be sized to the SMACNA 5-minute, 100-year rainfall intensity, or to the basis required by the Authority Having Jurisdiction, whichever produces the larger cross-section.
+
+## The design rainfall intensity used for sizing shall be recorded on the sizing calculations and on the construction documents.
+
+```datasheet
+label: Design rainfall intensity (5-minute, 100-year basis)
+type: range
+unit: in/hr
+min: 4
+max: 11
+step: 0.5
+```
+
+## In cold climates, gutters carry ground snow and ice loads and are subject to ice damming, so hanger spacing and gutter attachment must account for snow load rather than rainwater weight alone. {note}
+
+## Where the ground snow load exceeds 25 psf, hanger spacing and attachment shall be designed for the snow and ice load on the gutter, not for water weight alone.
+
+```datasheet
+label: Ground snow load (governs hanger spacing)
+type: range
+unit: psf
+min: 0
+max: 90
+step: 5
+```
+
+## Coastal, industrial, and high-pollution exposures accelerate corrosion of bare and coated metals, and they govern the choice between a standard polyester finish and a premium PVDF finish as well as the choice of substrate. {note}
+
+```datasheet
+label: Exterior exposure severity
+type: radio
+options:
+ - Moderate (inland, suburban)
+ - Severe (coastal, industrial, high-pollution)
+default: Moderate (inland, suburban)
+```
+
+# Materials {toc}
+
+## Material selection is the first decision and it drives every downstream compatibility constraint: fastener metal, solder or sealant joint method, and contact with adjacent roof-edge metals. Prefinished aluminum is the 80% commercial default; galvanized steel and Galvalume are economical alternatives; copper and zinc are premium institutional, historic, and high-exposure choices. {note}
+
+```datasheet
+label: Gutter and downspout substrate material
+type: radio
+options:
+ - Prefinished aluminum (alloy 3105-H24)
+ - Galvanized steel (G90)
+ - Galvalume (AZ50)
+ - Copper (ASTM B370)
+ - Zinc alloy
+default: Prefinished aluminum (alloy 3105-H24)
+```
+
+## Aluminum {toc}
+
+### Aluminum gutter and downspout coil shall be alloy 3105-H24 conforming to ASTM B209.
+
+### Aluminum is specified by decimal thickness, not by gauge; stating a gauge for aluminum is ambiguous because the gauge-to-thickness relationship differs from steel. The commercial default is 0.032 in for 5 in and 6 in gutters, with 0.027 in acceptable for residential and light-commercial work and 0.040 in for heavy-commercial and built-in gutters. {note}
+
+### Aluminum sheet thickness shall not be less than the value scheduled for the gutter size and exposure.
+
+```datasheet
+label: Aluminum sheet thickness
+type: radio
+options:
+ - 0.027 in (residential / light commercial)
+ - 0.032 in (commercial default, 5 in and 6 in)
+ - 0.040 in (heavy commercial / built-in)
+default: 0.032 in (commercial default, 5 in and 6 in)
+```
+
+## Galvanized Steel {toc}
+
+### Galvanized steel gutter and downspout sheet shall conform to ASTM A653/A653M with a G90 zinc coating designation.
+
+### A G60 coating is a residential minimum and shall not be used for commercial gutters; G90 is required for commercial durability because the heavier zinc coating substantially extends service life in the standing-water and debris environment of a gutter. {note}
+
+### Prepainted galvanized steel gutter stock shall conform to ASTM A755/A755M for the coil-coating process.
+
+```datasheet
+label: Galvanized steel gauge and coating
+type: radio
+options:
+ - 26 gauge, G90 (residential minimum)
+ - 24 gauge, G90 (commercial default)
+ - 22 gauge, G90 (built-in / box gutters)
+default: 24 gauge, G90 (commercial default)
+```
+
+## Galvalume {toc}
+
+### Galvalume gutter and downspout sheet shall conform to ASTM A792/A792M with an AZ50 coating class.
+
+### Galvalume offers longer corrosion life than galvanized steel at similar cost, but its cut edges and fastener penetrations require the same compatible-fastener discipline as any coated steel. {note}
+
+## Copper {toc}
+
+### Copper gutter and downspout sheet shall conform to ASTM B370, minimum H00 temper.
+
+### Copper weight is selected by application: 16 oz/sq ft (0.0216 in) is the default for hung gutters, and 20 oz/sq ft (0.0270 in) is required for built-in gutters, which carry more water and more structural and thermal stress. {note}
+
+### Hung copper gutters shall be a minimum of 16 oz/sq ft.
+
+### Built-in copper gutters shall be a minimum of 20 oz/sq ft.
+
+```datasheet
+label: Copper weight
+type: radio
+options:
+ - 16 oz/sq ft (hung gutters)
+ - 20 oz/sq ft (built-in gutters)
+default: 16 oz/sq ft (hung gutters)
+```
+
+## Fasteners and Accessories {toc}
+
+### Fasteners, hangers, rivets, and solder shall be the same metal as the gutter or a metal that is galvanically compatible with it; carbon-steel fasteners shall not contact copper or aluminum.
+
+### Aluminum gutters shall be fastened with aluminum or stainless steel fasteners.
+
+### Copper gutters shall be fastened with copper or copper-alloy fasteners and joined with lead-free solder suitable for copper.
+
+### Galvanic incompatibility is the dominant premature-failure mode for gutters: pairing aluminum gutters with copper downspouts or fasteners, or carbon-steel screws with either, sets up a corrosion cell that fails the joint long before the metal would otherwise wear out. Specifying a single metal family throughout, with stainless steel as the only mixed-metal fastener allowance, eliminates the risk. {note}
+
+```datasheet
+label: Fastener / hanger material
+type: radio
+options:
+ - Matching gutter metal
+ - Stainless steel (compatible with all)
+default: Stainless steel (compatible with all)
+```
+
+# Gutter Configuration {toc}
+
+## The gutter profile sets capacity, appearance, fabrication method, and hanger type. K-style (ogee) is the commercial default and develops the most capacity per face height; half-round is favored for traditional and copper work and sheds debris well; box/built-in (yankee) gutters are custom shop-fabricated, often historic or institutional, and carry structural and overflow obligations addressed in their own section. {note}
+
+```datasheet
+label: Gutter profile
+type: radio
+options:
+ - K-style (ogee)
+ - Half-round
+ - Box / built-in (yankee)
+default: K-style (ogee)
+```
+
+## Gutter width shall be sized to the governing rainfall intensity and projected roof area, with the larger of the SMACNA-table result and the code-required result governing.
+
+## A 5 in seamless K-style gutter on a 1% slope serves roughly 4,000 to 5,300 sq ft of projected roof area at a 4 in/hr intensity, and that area shrinks as intensity rises; published SMACNA tables, not rules of thumb, are the basis of record for each project. {note}
+
+```datasheet
+label: K-style gutter width
+type: radio
+options:
+ - 4 in
+ - 5 in
+ - 6 in
+ - 7 in
+ - 8 in
+default: 5 in
+```
+
+```datasheet
+label: Half-round gutter width
+type: radio
+options:
+ - 4 in
+ - 5 in
+ - 6 in
+ - 8 in
+default: 6 in
+```
+
+## Seam Type {toc}
+
+### Seamless field-formed gutter eliminates the slip joints that are the most common leak path in sectional gutter, and it is preferred for commercial work. Sectional gutter, formed in shop lengths and joined with sealed slip joints, is acceptable where seamless field-forming is impractical, such as short or obstructed runs. {note}
+
+### Continuous runs shall be field-formed seamless on a coil-forming machine where the run geometry permits, with slip joints used only at expansion joints and at field-determined obstructions.
+
+### Where seamless gutter is specified, the contractor shall confirm by submittal that runs are field-formed and not shop-fabricated sections substituted as seamless.
+
+```datasheet
+label: Gutter seam type
+type: radio
+options:
+ - Seamless field-formed
+ - Sectional with sealed slip joints
+default: Seamless field-formed
+```
+
+## Slope {toc}
+
+### Gutter slope toward outlets shall be not less than 1/16 in per foot.
+
+### Gutter slope of 1/8 in per foot shall be the preferred default; for runs exceeding 50 ft, slope shall be not less than 1/4 in per foot.
+
+### Gutter slope shall be shown on the drawings and shall not be left to the installer's field determination.
+
+### Too little slope leaves standing water that accelerates corrosion and freezes, while inconsistent field slope produces low spots that overflow. {note}
+
+```datasheet
+label: Gutter slope to outlet
+type: radio
+options:
+ - 1/16 in per foot (absolute minimum)
+ - 1/8 in per foot (preferred default)
+ - 1/4 in per foot (runs over 50 ft)
+default: 1/8 in per foot (preferred default)
+```
+
+## Finish {toc}
+
+### Prefinished gutter and downspout coatings shall be one of: a PVDF (70% resin) coating meeting AAMA 2605, a polyester coating meeting AAMA 2604, mill (bare) aluminum, or the natural patina finish of bare copper or zinc.
+
+### A PVDF coating with minimum 70% resin content per AAMA 2605 carries a 20-year color and chalk warranty and is the default for most commercial specifications; a polyester coating meeting AAMA 2604 is acceptable for moderate exposure at lower cost. The premium finish is justified wherever the gutter is architecturally exposed or the exposure is severe. {note}
+
+```datasheet
+label: Prefinish coating
+type: radio
+options:
+ - PVDF / 70% resin (AAMA 2605, commercial default)
+ - Polyester (AAMA 2604)
+ - Mill / bare aluminum
+ - Bare copper or zinc (natural patina)
+default: PVDF / 70% resin (AAMA 2605, commercial default)
+```
+
+## Leaf Guards and Strainers {toc}
+
+### A removable strainer or basket shall be provided at each outlet to keep leaves and debris from entering the downspout.
+
+### Whether continuous leaf protection is provided, and of what type, shall be specified explicitly rather than left to the installer, because the choice changes the maintenance interval and the assumed debris load. {note}
+
+```datasheet
+label: Continuous leaf protection
+type: radio
+options:
+ - None (strainer baskets at outlets only)
+ - Open-mesh screen
+ - Solid-hood micro-mesh
+default: None (strainer baskets at outlets only)
+```
+
+# Downspouts {toc}
+
+## Downspouts carry collected water from gutter outlets down the building face to a discharge point. Profile and size are selected to drain the area tributary to each outlet: a 3x4 in rectangular downspout drains roughly 1,200 sq ft at 4 in/hr and a 4x5 in roughly 2,400 sq ft, with round equivalents handling comparable areas. {note}
+
+## Downspout size and count shall provide a combined cross-sectional area sufficient to drain the projected roof area tributary to each gutter at the design rainfall intensity, in accordance with the SMACNA tables and IPC Section 1106.
+
+```datasheet
+label: Downspout profile
+type: radio
+options:
+ - Rectangular smooth-wall
+ - Rectangular corrugated
+ - Round corrugated
+default: Rectangular smooth-wall
+```
+
+```datasheet
+label: Rectangular downspout size
+type: radio
+options:
+ - 2x3 in (residential)
+ - 3x4 in (commercial default)
+ - 4x5 in (large roof areas)
+default: 3x4 in (commercial default)
+```
+
+```datasheet
+label: Round downspout diameter
+type: radio
+options:
+ - 3 in
+ - 4 in
+default: 4 in
+```
+
+## Outlets {toc}
+
+### Each gutter outlet shall be an inside or outside miter outlet, drop outlet, or round outlet tube matched to the downspout profile and sized to the downspout cross-section.
+
+### The outlet tube and the downspout it feeds shall be the same metal, or galvanically compatible metals, joined without dissimilar-metal contact.
+
+```datasheet
+label: Outlet type
+type: radio
+options:
+ - Drop outlet (in gutter bottom)
+ - Inside/outside miter outlet
+ - Round outlet tube
+default: Drop outlet (in gutter bottom)
+```
+
+## Downspout Routing and Offsets {toc}
+
+### Downspouts shall be secured to the wall with straps or brackets at the spacing required to resist wind and the weight of a full downspout, and at each elbow.
+
+### Where the gutter is pitched away from the structure, the downspout shall be returned to the wall with offset elbows so the downspout runs against the face of the building, and the elbow type and wall clearance shall be detailed [[drawing: gutter and downspout elevations]].
+
+### Downspout locations are an architectural and drainage coordination item that must be fixed on the drawings; leaving them to the field produces uneven tributary areas and overflow at the under-served outlets. {note}
+
+## Downspout Termination {toc}
+
+### Each downspout shall terminate at grade in a splash block, at an underground connection to the storm system, at a through-wall fitting, or at a dry well, as scheduled for the project location [[drawing: downspout discharge locations]].
+
+### The responsible party for each downspout discharge termination shall be defined in the construction documents.
+
+### An undefined boundary between a splash block (this scope) and an underground storm connection (often site civil, not in this contract) is a recurring source of field RFIs about who furnishes and installs the connection fitting. {note}
+
+```datasheet
+label: Downspout discharge termination
+type: radio
+options:
+ - Splash block at grade
+ - Underground connection to storm system
+ - Through-wall fitting
+ - Dry well
+default: Splash block at grade
+drawing_ref: "downspout discharge locations"
+```
+
+# Expansion Joints {toc}
+
+## Gutters are long, continuous metal elements that expand and contract with temperature, and without expansion joints at controlled intervals the gutter buckles, splits at miters, and leaks. Maximum spacing depends on material: aluminum every 40 ft (50 ft with a designed slip-joint), galvanized steel every 30 to 40 ft, and copper every 30 ft with soldered slip sleeves. {note}
+
+## Expansion joints shall be provided at the maximum spacing scheduled for the gutter material and shall be shown on the drawings rather than left to the installer.
+
+## Expansion joint locations shall be coordinated with outlet and downspout positions so that each gutter segment between joints drains to at least one outlet.
+
+```datasheet
+label: Expansion joint maximum spacing
+type: radio
+options:
+ - 40 ft (aluminum)
+ - 50 ft (aluminum, designed slip-joint)
+ - 30-40 ft (galvanized steel)
+ - 30 ft (copper, soldered slip sleeve)
+default: 40 ft (aluminum)
+```
+
+# Hangers and Supports {toc}
+
+## Concealed hidden-hanger clips are the current standard; spike-and-ferrule hangers are obsolete and shall not be used. {note}
+
+## Gutters shall be supported on concealed hidden-hanger clips, concealed brackets, fascia-mount straps, or standoff brackets matched to the eave condition and the gutter profile.
+
+## Concealed-bracket hanger spacing shall not exceed 24 in on center for aluminum gutters under normal conditions.
+
+## Where the ground snow load exceeds 25 psf, hanger spacing shall not exceed 16 in on center, or structural strap hangers shall be used, so the gutter and its attachment carry the snow and ice load without pulling away from the fascia.
+
+```datasheet
+label: Hanger spacing
+type: radio
+options:
+ - 24 in on center (normal conditions)
+ - 16 in on center (ground snow load over 25 psf)
+default: 24 in on center (normal conditions)
+```
+
+```datasheet
+label: Hanger type
+type: radio
+options:
+ - Concealed hidden-hanger clip
+ - Concealed bracket
+ - Fascia-mount strap
+ - Standoff bracket (exposed rafter tails)
+default: Concealed hidden-hanger clip
+```
+
+# Leader Heads and Conductor Heads {toc}
+
+## A leader head (conductor head) is an open collection box at the top of a downspout that receives water from a gutter outlet or scupper and provides overflow relief and a decorative element. Where leader heads appear on the architectural elevations they must be specified here, or the contractor will issue an RFI or omit them; the alternative is an explicit cross-reference to [[sync/sheet-metal-flashing-and-trim]] if the leader heads are owned there. {note}
+
+## Leader heads, where scheduled, shall be fabricated of the same metal and finish as the gutters and downspouts they serve.
+
+## Ornamental leader heads at major facade locations shall be detailed [[drawing: leader head locations and profiles]]; plain leader heads at utilitarian locations may be standard manufactured units.
+
+```datasheet
+label: Leader head / conductor head
+type: radio
+options:
+ - None
+ - Plain (utilitarian locations)
+ - Ornamental (major facade locations)
+default: None
+```
+
+# Box and Built-In Gutters {toc}
+
+## A box or built-in gutter is set into the roof edge or cornice and becomes part of the structure rather than hanging from the fascia, so it carries water loads that an eave-hung gutter never sees and it has no automatic overflow path if the outlet blocks. {note}
+
+## Built-in gutters shall be designed in coordination with the structural engineer for the rain load and ponding condition determined under ASCE 7 Chapter 8.
+
+## Overflow scuppers shall be provided as a mandatory secondary drainage path for every built-in gutter, sized and located in coordination with [[sync/roof-drainage]].
+
+## Built-in gutters shall be lined continuously with the specified metal, with soldered or welded joints appropriate to the lining material, and shall not rely on sealant alone at the lining seams.
+
+## The combination of structural load, ponding risk, and concealed location makes a built-in gutter the highest-consequence configuration in this standard; the structural coordination and the overflow-scupper backup are not optional refinements but the conditions under which a built-in gutter may be used at all. {note}
+
+```datasheet
+label: Built-in gutter overflow provision
+type: checkbox
+options:
+ - Overflow scuppers provided (coordinate with roof-drainage)
+ - Structural ponding check per ASCE 7 Chapter 8 completed
+ - Continuous soldered/welded metal lining
+default:
+ - Overflow scuppers provided (coordinate with roof-drainage)
+ - Structural ponding check per ASCE 7 Chapter 8 completed
+ - Continuous soldered/welded metal lining
+```
+
+# Testing {toc}
+
+## Completed gutters and downspouts shall be water-tested by flooding representative runs and confirming flow to the outlets and downspouts with no leakage at joints, miters, end caps, or outlets.
+
+## Slope shall be verified after installation by confirming that no standing water remains in the gutter after a water test drains, because a low spot that holds water is both a corrosion site and a freeze hazard. {note}
+
+## Soldered copper and zinc joints shall be visually inspected for full, continuous solder fill at every seam and outlet.
+
+# Installation {toc}
+
+## Gutters and downspouts shall be installed in accordance with the approved shop drawings, the SMACNA fabrication details, and the gutter manufacturer's instructions for the specified profile and material.
+
+## Gutters shall be installed to the slope and expansion-joint layout shown on the drawings, with hangers at the scheduled spacing, and with outlets positioned so each gutter segment drains as designed.
+
+## End caps and miters shall be sealed or soldered watertight according to the gutter material, using lead-free solder for copper and zinc and the specified sealant for aluminum and coated steel.
+
+## Dissimilar-metal contact shall be prevented at every interface between the gutter system and adjacent roof-edge metals, fasteners, and supports, using isolation or compatible materials.
+
+## Gutters shall be installed below the slope line of the roof so that snow and water sliding off the roof clear the back of the gutter and discharge into it, and shall not block the roof drainage edge.
+
+## Downspouts shall be installed plumb, strapped at the scheduled spacing and at each elbow, with offset elbows returning the downspout to the wall where required.
+
+## Penetrations, cut edges, and field-formed seams in coated steel and Galvalume shall be touched up or sealed so that no bare cut edge or fastener penetration is left exposed to accelerate corrosion.
+
+# Delivery, Storage, and Handling {toc}
+
+## Prefinished gutter coil and fabricated sections shall be delivered with the factory finish protected and shall be stored off the ground, under cover, and sloped to drain.
+
+## Coil and fabricated sections shall be handled to avoid kinking, scratching the finish, or deforming the profile, because a deformed profile cannot be field-corrected without weakening the metal or marring the finish.
+
+## Dissimilar metals shall be separated in storage so that copper, steel, and aluminum products do not bear on one another and transfer corrosion-promoting contact.
+
+# Warranty {toc}
+
+## The Contractor shall warrant the installed gutter and downspout system against leakage and defective workmanship for a period of not less than two years from Substantial Completion.
+
+## The finish warranty for PVDF-coated products shall provide not less than 20 years of coverage against color change and chalking consistent with AAMA 2605.
+
+## The manufacturer's material and coating warranties shall be transferred to the Owner at closeout.
+
+```datasheet
+label: Workmanship warranty period
+type: radio
+options:
+ - 2 years
+ - 5 years
+default: 5 years
+```
+
+```datasheet
+label: Finish warranty period (PVDF)
+type: radio
+options:
+ - 20 years
+ - 25 years
+default: 20 years
+```
+
+# Spare Parts {toc}
+
+## The Contractor shall furnish to the Owner not less than one full coil or representative length of each gutter profile and finish used on the project for future repair.
+
+## The Contractor shall furnish spare strainer baskets and a representative quantity of hangers, outlets, and downspout sections matching those installed.
+
+```datasheet
+label: Spare materials furnished
+type: checkbox
+options:
+ - Gutter coil / length per profile and finish
+ - Strainer baskets
+ - Hangers, outlets, downspout sections
+default:
+ - Gutter coil / length per profile and finish
+ - Strainer baskets
+```