−---
−title: Roof Drainage
−category: Plumbing
−toc_depth: 3
−description: >
− When to use: Roof drainage systems on and within the building, including primary roof drains, the required secondary (overflow) drainage by overflow roof drains or overflow scuppers, vertical rainwater leaders and conductors, and horizontal storm drainage piping within the building from each roof drain to the point of connection with the site storm drainage system. Covers rainfall-rate-based sizing, drain types (roof, overflow, deck, balcony, planter, and area drains), controlled-flow roof drainage, drain bodies with domes and strainers, flashing- and membrane-clamp integration with the roofing, piping materials, joining, hangers and supports, expansion provisions, and condensation insulation of conductors. Applicable to commercial, institutional, and industrial buildings with low-slope and steep-slope roofs.
− Not intended for: Site and underground storm drainage outside the building from the point of connection onward, including catch basins, manholes, detention, and outfalls (see [[sync/storm-drainage]]); sanitary drain, waste, and vent piping (see [[sync/sanitary-waste-and-vent-piping]]); gutters and downspouts that are part of the roofing or sheet-metal scope (see [[sync/membrane-roofing]]); the roof membrane, membrane flashing, and roof insulation themselves (see [[sync/membrane-roofing]]); foundation and subsurface drainage; rainwater harvesting and cistern storage systems; and siphonic roof drainage systems, which require manufacturer-engineered design beyond the gravity-flow scope of this standard.
−---
−
−# Scope
−
−This standard covers the design coordination, material selection, fabrication, installation, testing, and acceptance of roof drainage systems on and within the building. The scope encompasses primary roof drains and their bodies, domes, strainers, and flashing-clamp assemblies; the secondary (overflow) drainage system required to protect the structure when the primary system is blocked, provided either as overflow roof drains or as overflow scuppers; the vertical rainwater leaders and conductors that carry roof flow downward through the building; and the horizontal storm drainage piping within the building from the base of each leader to the point of connection with the site storm drainage system.
−
−Roof drainage is a life-safety scope, not merely a plumbing convenience. A blocked or undersized primary drainage system with no functioning secondary system allows water to pond on the roof; ponded water is one of the heaviest live loads a roof can experience, and progressive ponding has collapsed roofs that were otherwise structurally sound. For this reason the secondary drainage system is required to be sized and routed independently of the primary system, on the assumption that the primary system is completely blocked. The narrative throughout this standard is written to preserve that independence and to close the gaps between code-minimum drainage and reliable long-term performance.
−
−This standard does not include the site or underground storm drainage system that begins at the building's point of connection. Where the building storm drain exits the building and connects to the site storm system, the transition point shall be as indicated on [[drawing: the plumbing and civil drawings]] and the downstream system is governed by [[sync/storm-drainage]]. The roof membrane, membrane base flashing, tapered roof insulation, and roof slope-to-drain are part of the roofing scope and are governed by [[sync/membrane-roofing]]; this standard governs only the drain components that penetrate and clamp to the roof assembly and the piping below. Condensation insulation of conductors and drain bodies is coordinated with [[sync/plumbing-insulation]].
−
−# Referenced Standards
−
−Materials, equipment, and installation shall comply with the latest adopted edition of the following standards and codes unless a specific year is cited elsewhere in the contract documents. Where the contract documents or a referenced standard conflicts with the adopted building or plumbing code, the more stringent requirement governs unless the Engineer of Record directs otherwise in writing.
−
−| Standard | Title |
−|----------|-------|
−| IPC | International Plumbing Code (Chapter 11 — Storm Drainage) |
−| UPC | Uniform Plumbing Code (Chapter 11 — Storm Drainage) |
−| IBC | International Building Code (Section 1503.4 — Roof Drainage; Section 1611 — Rain Loads) |
−| ASME A112.6.4 | Roof, Deck, and Balcony Drains |
−| ASME A112.6.3 | Floor and Trench Drains (area and deck drains connected to storm system) |
−| ASME A112.21.2M | Roof Drains (legacy reference; superseded by A112.6.4) |
−| ASTM A74 | Standard Specification for Cast Iron Soil Pipe and Fittings (hub and spigot) |
−| ASTM A888 | Standard Specification for Hubless Cast Iron Soil Pipe and Fittings for Sanitary and Storm Drain, Waste, and Vent Piping Applications |
−| CISPI 301 | Standard Specification for Hubless Cast Iron Soil Pipe and Fittings for Sanitary and Storm Drain, Waste, and Vent Piping Applications |
−| CISPI 310 | Specification for Coupling for Use in Connection with Hubless Cast Iron Soil Pipe and Fittings |
−| ASTM C1277 | Standard Specification for Shielded Couplings Joining Hubless Cast Iron Soil Pipe and Fittings |
−| ASTM C564 | Standard Specification for Rubber Gaskets for Cast Iron Soil Pipe and Fittings |
−| ASTM D2665 | Standard Specification for Poly(Vinyl Chloride) (PVC) Plastic Drain, Waste, and Vent Pipe and Fittings |
−| ASTM D2564 | Standard Specification for Solvent Cements for Poly(Vinyl Chloride) (PVC) Plastic Pipe and Fittings |
−| ASTM F656 | Standard Specification for Primers for Use in Solvent Cement Joints of PVC Plastic Pipe and Fittings |
−| ASTM B306 | Standard Specification for Copper Drainage Tube (DWV) |
−| MSS SP-58 | Pipe Hangers and Supports — Materials, Design and Manufacture |
−| MSS SP-69 | Pipe Hangers and Supports — Selection and Application |
−| ASME A13.1 | Scheme for the Identification of Piping Systems |
−| NSF/ANSI 14 | Plastics Piping System Components and Related Materials |
−
−Where the project is located in a jurisdiction that has adopted the Uniform Plumbing Code rather than the International Plumbing Code, references to IPC chapter and section numbers shall be understood to refer to the equivalent UPC provisions. The Contractor shall confirm the adopted edition and any local amendments with the Authority Having Jurisdiction prior to submitting the permit application.
−
−# Submittals
−
−## Action Submittals
−
−Contractor shall submit the following for the Engineer's review and comment prior to fabrication, procurement, or installation of any portion of the work. No substitutions for specified materials shall be used until the substitution has been reviewed and accepted in writing.
−
−- Product data for all roof drains, overflow roof drains, deck drains, balcony drains, planter drains, and area drains, including the drain body material, outlet size and type, dome or strainer type and free area, flashing-clamp / gravel-guard configuration, underdeck clamp, sump receiver, and any extension or expansion accessories, with confirmation of compliance with ASME A112.6.4
−- Product data for all piping materials, including pipe and fittings conforming to the applicable ASTM or CISPI standard, with confirmation of the standard designation and applicable weight or schedule class
−- Product data for shielded couplings for hubless cast iron pipe, including the manufacturer's published torque specification and listing information
−- Roof drainage sizing calculations showing the design rainfall rate used, the roof area tributary to each drain, the resulting required drain, leader, and horizontal pipe sizes, and the independent sizing of the secondary (overflow) system assuming the primary system is fully blocked
−- Coordination drawings showing each drain location relative to the structural roof framing, the roof slope-to-drain, the membrane flashing clamp interface, and the leader routing through the building
−- Product data for pipe hangers, supports, riser clamps, and seismic restraints, including the manufacturer's load tables for the sizes and pipe materials specified
−- Condensation insulation product data and the extent of insulated piping, coordinated with [[sync/plumbing-insulation]]
−- Penetration details for all fire-rated floor and wall penetrations, with fire-stop product data and listed assembly numbers
−
−```datasheet
−label: Action Submittals Required
−type: checkbox
−options:
− - "Roof drain, overflow drain, and specialty drain product data (ASME A112.6.4)"
− - "Pipe and fitting product data"
− - "Shielded coupling product data with torque specification"
− - "Roof drainage sizing calculations (primary and independent secondary)"
− - "Drain location and leader routing coordination drawings"
− - "Hanger, support, and seismic restraint product data with load tables"
− - "Condensation insulation product data and extent"
− - "Fire-stop penetration details"
−default: "Roof drainage sizing calculations (primary and independent secondary)"
−```
−
−## Closeout Submittals
−
−Contractor shall provide the following at substantial completion before the roof drainage system is accepted.
−
−- As-built drawings showing the installed drain locations, leader routing, horizontal piping invert elevations at cleanouts and connection points, and any deviations from the contract documents
−- Field test reports for all water and air tests performed on the storm piping, signed by the testing technician, with pass/fail determination and corrective actions taken
−- Manufacturer's warranty documentation for roof drains and specialty drainage products
−- Operation and maintenance data covering drain dome and strainer cleaning intervals and secondary-system inspection recommendations
−
−# Quality Assurance
−
−## Installer Qualifications
−
−All roof drainage piping shall be installed by a licensed plumbing contractor and by journeymen or apprentice plumbers working under the direct supervision of a licensed journeyman. The installing contractor shall have verifiable experience in commercial storm drainage installation on at least three projects of comparable size and complexity within the preceding five years.
−
−## Listing and Marking
−
−All drains, pipe, fittings, and couplings shall be listed and marked by a nationally recognized testing laboratory for the applicable product standard. Roof drains shall bear the ASME A112.6.4 designation and the manufacturer's identification. Cast iron soil pipe shall be marked with the applicable standard designation (ASTM A74 or ASTM A888 / CISPI 301), the pipe weight class, and the manufacturer's identification. PVC pipe shall carry the NSF/ANSI 14 listing mark. Unlisted or unmarked pipe, fittings, and drains shall be rejected and removed from the project regardless of documentation provided by the supplier.
−
−## Coordination with the Roofing Trade
−
−The roof drain flashing-clamp interface is a shared responsibility between the plumbing and roofing trades, and the most common source of roof leaks at drains is a poorly coordinated clamp installation. The Contractor shall coordinate the setting elevation of each drain body, the sequence of membrane installation and clamp-ring tightening, and the responsibility for the membrane target sheet or flashing collar with the roofing contractor before any drain is set. The roof drain body shall be set so that its flange sits in the plane of the roof structural deck or sump, with the membrane clamping ring positioned to clamp the roofing membrane uniformly to the drain flange. Coordination shall conform to the requirements of [[sync/membrane-roofing]] for the membrane-side detailing.
−
−## Regulatory Inspection Hold Points
−
−The Contractor shall schedule inspections by the Authority Having Jurisdiction for the rough storm piping before concealment. No portion of the storm drainage system shall be concealed before the applicable rough plumbing inspection has been completed and released.
−
−# Storm Drainage Design Basis
−
−## Design Rainfall Rate
−
−The size of all roof drains, leaders, conductors, and horizontal storm piping shall be based on the local design rainfall rate. Unless the contract documents specify otherwise, the design rainfall rate shall be the 100-year, 1-hour rainfall rate for the project location, expressed in inches per hour, taken from the rainfall figures in IPC Section 1106 or from approved local weather data. The design rainfall rate is a project-specific value and shall be confirmed against the geographic location before sizing.
−
−```datasheet
−label: Design Rainfall Rate (100-year, 1-hour)
−type: range
−unit: in/hr
−drawing_ref: true
−options:
− min: 1
− max: 10
− setpoints: [2, 3, 4, 5, 6, 7, 8]
−default: 4
−```
−
−The 100-year, 1-hour rainfall rate varies widely across the United States, from roughly 2 in/hr in the arid interior west to 8 in/hr or more along the Gulf Coast and parts of the southeast. The default value of 4 in/hr is representative of much of the central and eastern United States but must not be used without confirming the value for the actual project location, because under-sizing the drainage system to an incorrect rainfall rate defeats the entire purpose of the design. The rainfall rate used shall be recorded on the sizing calculation submittal.
−
−## Tributary Roof Area
−
−Each roof drain shall be assigned the roof area that drains to it, including any adjacent vertical wall area that sheds water onto the roof in accordance with the adopted code's vertical-wall area provisions. Tributary areas, drain locations, and roof slope-to-drain shall be [[drawing: as indicated on the roof plan and the plumbing roof drainage plan]]. The Contractor shall verify that the drain locations shown produce the tributary areas assumed in the sizing calculations and shall report any discrepancy to the Engineer of Record before installation.
−
−## Primary System Sizing
−
−Vertical leaders, conductors, and horizontal storm drains for the primary system shall be sized for the design rainfall rate and the tributary area in accordance with the sizing tables of the adopted plumbing code (IPC Section 1106 or the UPC equivalent). No reduction in pipe size shall be made in the direction of flow. Horizontal storm piping shall be sized for its installed slope; flatter slopes require larger pipe to carry the same flow.
−
−```datasheet
−label: Primary Leader and Pipe Sizes
−type: select
−drawing_ref: true
−options:
− - "2 inch"
− - "3 inch"
− - "4 inch"
− - "5 inch"
− - "6 inch"
− - "8 inch"
− - "10 inch"
− - "12 inch"
− - "Per drawings"
−default: "Per drawings"
−```
−
−## Secondary (Overflow) System Sizing — Independent of Primary
−
−A secondary (overflow) drainage system shall be provided wherever the roof construction extends above the roof surface in a manner that would entrap water if the primary drains became blocked — which describes nearly every roof bounded by a parapet, an equipment screen wall, or an adjacent higher structure. The secondary system shall be sized for the full design rainfall rate on the assumption that the primary drainage system is completely blocked; the flow capacity of the primary system shall not be credited when sizing the secondary system. This is the single most important requirement in this standard: the secondary system exists to protect the structure from ponding collapse when the primary system fails, and crediting the primary capacity would defeat that protection.
−
−```datasheet
−label: Secondary (Overflow) Drainage Method
−type: radio
−options:
− - "Overflow roof drains with independent piping to a conspicuous discharge"
− - "Overflow scuppers through the parapet wall"
− - "Combination — overflow drains at interior low points, scuppers at parapet"
− - "Per drawings"
−default: "Overflow roof drains with independent piping to a conspicuous discharge"
−```
−
−The choice between overflow roof drains and overflow scuppers is driven by roof geometry. Overflow scuppers are simple, reliable, and require no additional interior piping, and they are the preferred method wherever a parapet wall is adjacent to the roof low point. Overflow roof drains are required where the roof low point is remote from any exterior wall, where the parapet is too high to scupper economically, or where the architecture does not permit a parapet penetration. Overflow drains carry the disadvantage of requiring a complete independent piping system, but they are unavoidable on large interior roof areas.
−
−# Roof Drains
−
−## General
−
−Roof drains shall conform to ASME A112.6.4 and shall be of the type, body material, outlet size, and accessory configuration indicated. Each drain shall be furnished with a body, a removable dome or strainer, a combination membrane flashing clamp and gravel guard, and the deck-attachment and extension accessories appropriate to the roof assembly. Drain types, sizes, and locations shall be [[drawing: as indicated on the plumbing roof drainage plan and the roof drain schedule]].
−
−## Drain Body Material
−
−```datasheet
−label: Roof Drain Body Material
−type: radio
−options:
− - "Cast iron with corrosion-resistant coating"
− - "Cast iron with epoxy or PVC coating (corrosive or coastal environments)"
− - "Cast aluminum (weight-sensitive applications)"
− - "Per drawings"
−default: "Cast iron with corrosion-resistant coating"
−```
−
−Coated cast iron is the standard drain body material for commercial and institutional roofs. Its mass and rigidity hold the flashing-clamp interface flat under thermal cycling, and the coating protects against the corrosive concentration of roof runoff. Cast aluminum bodies are used where roof structural weight is a governing concern or where the drain is mounted in a lightweight deck, but aluminum is less tolerant of the abrasion and impact of roof maintenance traffic. Epoxy- or PVC-coated cast iron is warranted in coastal salt-air environments and where the roof receives chemical exhaust.
−
−## Drain Outlet Type
−
−```datasheet
−label: Roof Drain Outlet Connection
−type: radio
−options:
− - "No-hub outlet (hubless cast iron coupling connection)"
− - "Inside-caulk outlet (hub-and-spigot)"
− - "Threaded outlet"
− - "Per drawings"
−default: "No-hub outlet (hubless cast iron coupling connection)"
−```
−
−The drain outlet shall match the leader piping material and joining method. No-hub outlets connecting to hubless cast iron couplings are the most common configuration in modern commercial construction and allow the drain to be set and the leader connected without disturbing the membrane clamp once it is tightened.
−
−## Dome and Strainer
−
−Each primary roof drain on a low-slope roof shall be furnished with a removable dome-type strainer extending not less than 4 inches above the roof surface, with a free inlet area not less than 1.5 times the area of the drain outlet so that the strainer cannot become the flow-limiting element when partially blocked by debris. Drains on gravel-surfaced or ballasted roofs shall include a gravel guard or gravel stop integral with the flashing clamp to keep ballast out of the drain. Drains in walkable deck and balcony locations shall use a flat, secured grate rated for foot traffic rather than a dome, and shall comply with the slip-resistance and accessibility requirements applicable to the walking surface.
−
−```datasheet
−label: Primary Roof Drain Dome / Strainer Type
−type: select
−options:
− - "Cast iron dome strainer (low-slope roof, non-traffic)"
− - "Polyethylene / polymer dome strainer (low-slope roof, non-traffic)"
− - "Aluminum dome strainer (low-slope roof, non-traffic)"
− - "Flat secured grate (deck, balcony, walkable surfaces)"
− - "Per drawings"
−default: "Cast iron dome strainer (low-slope roof, non-traffic)"
−```
−
−The dome strainer's purpose is to keep leaves, debris, and ballast out of the leader while presenting enough free area that partial blockage does not choke the drain. Polymer domes are lighter and resist corrosion but can become brittle and crack under cold-weather impact from maintenance traffic; cast iron and aluminum domes are more durable for roofs that see regular foot traffic. The dome shall be removable for cleaning without tools where the roof is regularly maintained by the Owner's personnel.
−
−## Flashing Clamp and Membrane Integration
−
−Each drain shall be furnished with a combination membrane flashing clamp ring and gravel guard that clamps the roofing membrane uniformly to the drain body flange. The clamping ring shall be secured with the manufacturer's bolts at the spacing indicated in the drain's listing, tightened uniformly in a cross pattern so that the membrane is compressed evenly around the full circumference without wrinkles or gaps. The membrane-side detailing — the target sheet, the stripping, and the membrane termination at the clamp — shall be installed by the roofing trade in accordance with [[sync/membrane-roofing]]. The plumbing Contractor shall not tighten the clamp ring until the roofing membrane has been dressed into the drain and the roofing contractor confirms the membrane is ready to be clamped.
−
−## Underdeck Clamp and Deck Attachment
−
−Where the drain is set in a structural deck without a poured sump, the drain shall be furnished with an underdeck clamp that secures the drain body to the underside of the deck and transfers the drain weight and connected piping load to the structure rather than to the membrane or the leader. The drain shall not be supported by the leader piping alone. Where the drain is set in a poured concrete sump, the drain flange shall bear on the sump and the body shall be secured against rotation before the membrane is clamped.
−
−```datasheet
−label: Drain Deck Attachment
−type: radio
−options:
− - "Underdeck clamp to structural deck"
− - "Set in poured concrete roof sump"
− - "Sump receiver / sump pan for tapered insulation sump"
− - "Per drawings"
−default: "Underdeck clamp to structural deck"
−```
−
−## Extension and Adjustment
−
−Where the drain body must accommodate the thickness of rigid roof insulation between the structural deck and the membrane, a drain extension (sump extender) or an adjustable extension collar shall be provided so that the membrane flashing clamp finishes flush at the membrane plane while the drain body is anchored at the deck. The extension shall be of the same manufacturer and series as the drain body to ensure a sealed, listed assembly.
−
−# Overflow (Secondary) Drainage
−
−## Overflow Roof Drains
−
−Where overflow roof drains are used, each overflow drain shall be a roof drain conforming to ASME A112.6.4 with a water dam (standpipe collar) at its inlet so that the overflow inlet flow line is set not less than 2 inches above the adjacent roof low point. The 2-inch dam ensures that the overflow drain remains dry during normal operation and admits water only when the depth on the roof rises above the level at which the primary drain should have carried it away — that is, only when the primary drain is blocked. Overflow drains shall be of the same body material and dome type as the primary drains they back up.
−
−```datasheet
−label: Overflow Roof Drain Inlet Dam Height
−type: range
−unit: in
−options:
− min: 2
− max: 4
− setpoints: [2, 3, 4]
−default: 2
−```
−
−The minimum 2-inch dam height is the code requirement; it positions the overflow inlet above the normal flow depth at the primary drain. A taller dam may be specified where the roof structure can tolerate a greater ponding depth and the designer wishes to keep the overflow inactive under more frequent storms, but the dam height plus the head required to drive the design flow through the overflow drain must not exceed the ponding depth the roof structure is designed to carry. The dam height shall be coordinated with the structural rain-load analysis under IBC Section 1611.
−
−## Overflow Drain Piping — Independent and Conspicuous Discharge
−
−The piping serving overflow roof drains shall be entirely independent of the primary roof drain piping system from the drain to the point of discharge; the two systems shall not be combined at any point. The overflow piping shall discharge above grade at a location that is normally observed by building occupants or maintenance personnel — typically to a splash block, a downspout boot, or a wall outlet not more than the code-permitted height above grade. A conspicuous discharge is required so that flow from the overflow system is immediately visible as a signal that the primary system has failed and requires attention.
−
−```datasheet
−label: Overflow Drain Discharge Location
−type: select
−drawing_ref: true
−options:
− - "Through exterior wall to splash block at grade (conspicuous)"
− - "To downspout boot at grade, separate from primary downspouts"
− - "To a visible point above grade at a building entrance or occupied area"
− - "Per drawings"
−default: "Through exterior wall to splash block at grade (conspicuous)"
−```
−
−Overflow piping shall not be tied into the building storm drain, the site storm system, or any concealed discharge where occupants would not see it. A secondary system that discharges to the same concealed point as the primary system gives no warning that the primary system has failed, and a blockage common to both systems (a clogged building drain) would disable both at once.
−
−## Overflow Scuppers
−
−Where overflow scuppers are used, each scupper shall be an opening through the parapet or perimeter wall with the inlet flow line set not more than 2 inches above the adjacent roof low point and a clear opening height of not less than 4 inches. The scupper width shall be sized to carry the design rainfall flow from its tributary area at the head available within the roof structure's permitted ponding depth; where a scupper backs up a single primary roof drain, its opening shall be not less than the circumference of a primary roof drain sized for the same area. Scuppers shall be furnished with a sheet-metal or membrane-flashed sleeve through the wall and an exterior face that discharges clear of the wall to a conspicuous point.
−
−```datasheet
−label: Overflow Scupper Minimum Opening Height
−type: range
−unit: in
−options:
− min: 4
− max: 12
− setpoints: [4, 6, 8]
−default: 4
−```
−
−The 4-inch minimum opening height is a code floor; in practice the opening is sized for flow, and a wider, taller opening is often required to pass the design flow at the limited head the roof structure can tolerate. Scupper sleeves and their flashing shall be coordinated with the membrane and sheet-metal work under [[sync/membrane-roofing]]; the scupper is a wall and roofing penetration as much as a drainage device, and a poorly flashed scupper is a chronic leak source.
−
−# Conductors and Storm Piping
−
−## Conductor and Leader Materials
−
−Conductors (vertical leaders) and horizontal storm drainage piping within the building shall be of the materials indicated. Conductor pipe shall not be used as soil, waste, or vent pipe, and soil, waste, or vent pipe shall not be used as a conductor; the storm and sanitary systems shall remain separate within the building unless a combined system is specifically permitted by the Authority Having Jurisdiction and indicated on the drawings.
−
−```datasheet
−label: Interior Storm Piping Material
−type: radio
−options:
− - "Hubless cast iron (ASTM A888 / CISPI 301)"
− - "Hub-and-spigot cast iron (ASTM A74), compression gasket joints"
− - "Copper DWV (ASTM B306)"
− - "PVC DWV Schedule 40 (ASTM D2665)"
− - "Per drawings"
−default: "Hubless cast iron (ASTM A888 / CISPI 301)"
−```
−
−Hubless cast iron is the preferred material for interior storm conductors in commercial and institutional buildings for the same reasons it is preferred for sanitary piping: superior noise attenuation, impact resistance, fire resistance, and service life. The acoustic advantage matters for storm conductors because heavy rainfall produces a loud, intermittent rush of water that is objectionable in occupied spaces when carried by thin-wall plastic pipe. Copper DWV is used in exposed or architectural locations where appearance matters. PVC DWV is acceptable where noise is not a concern and the adopted code permits it, but shall not be used in chases adjacent to occupied spaces where acoustic performance is required, consistent with [[sync/sanitary-waste-and-vent-piping]].
−
−## Cast Iron — Hubless
−
−Hubless cast iron soil pipe and fittings used as storm conductors shall conform to ASTM A888 or CISPI 301 and shall be joined with shielded couplings conforming to CISPI 310 and ASTM C1277. Couplings shall have a stainless steel outer shield, stainless steel worm-drive clamp bands, and a neoprene sleeve gasket, and shall be installed with a calibrated torque wrench set to the coupling manufacturer's published torque. Service weight pipe shall be used unless extra-heavy weight is indicated for buried or heavily loaded locations.
−
−```datasheet
−label: Hubless Cast Iron Weight Class
−type: radio
−options:
− - "Service weight"
− - "Extra-heavy weight"
−default: "Service weight"
−```
−
−## Cast Iron — Hub-and-Spigot
−
−Hub-and-spigot cast iron storm conductors shall conform to ASTM A74 and shall be joined with compression rubber gaskets conforming to ASTM C564. Lead and oakum caulked joints shall not be used in new construction. The compression gasket joint creates a watertight, root-resistant seal and tolerates minor movement without the rigidity of solvent-cemented joints.
−
−## Copper DWV
−
−Copper drainage tube shall conform to ASTM B306 (DWV) and shall be joined with cast or wrought copper drainage fittings using lead-free solder or brazing. Copper conductors are appropriate for exposed architectural runs and for connection to copper roof drains; the Contractor shall protect copper conductors from galvanic contact with dissimilar metals at hangers and supports.
−
−## PVC DWV
−
−PVC pipe and fittings used as storm conductors shall conform to ASTM D2665, shall be Schedule 40, and shall carry the NSF/ANSI 14 listing mark. PVC shall be joined by the two-step primer-and-solvent-cement method using a primer conforming to ASTM F656 and solvent cement conforming to ASTM D2564. The primer is not optional; a joint made without primer does not develop the surface dissolution that creates a true chemical weld.
−
−## Pipe Size Schedule
−
−Pipe sizes shall be as indicated on the drawings and shall match the sizing calculations. No reduction in pipe size shall be made in the direction of flow. The Contractor shall verify that the pipe sizes shown comply with the sizing calculations for the design rainfall rate and tributary areas, and shall report any discrepancy to the Engineer of Record before installation.
−
−# Controlled-Flow Roof Drainage
−
−## Application
−
−Controlled-flow (restrictive-flow) roof drainage intentionally meters the rate at which rainwater leaves the roof, using the roof itself as temporary detention storage so that the leaders, conductors, and downstream storm system can be smaller than they would be for a conventional free-draining roof. Controlled-flow drainage shall be used only where the contract documents specifically require it — typically where the site storm system or a municipal connection has limited capacity and the jurisdiction requires on-roof detention — and only where the roof structure has been specifically designed to carry the resulting ponded-water load. Controlled-flow drainage shall not be applied to a roof that has not been structurally analyzed for the controlled ponding depth.
−
−```datasheet
−label: Controlled-Flow Roof Drainage
−type: radio
−options:
− - "Not used — conventional free-draining roof drainage"
− - "Used — controlled-flow primary drainage per drawings and structural analysis"
−default: "Not used — conventional free-draining roof drainage"
−```
−
−## Controlled-Flow Drain Requirements
−
−Where controlled-flow drainage is used, each primary drain shall be a controlled-flow roof drain with a calibrated weir or flow-restricting device that limits the discharge rate to the design metered flow at the corresponding head. The metered flow rate, the maximum design head (ponding depth) at each drain, and the corresponding structural roof loading shall be [[drawing: as indicated on the plumbing and structural drawings]]. A secondary (overflow) drainage system sized for the full design rainfall rate with the primary controlled-flow system assumed blocked shall always be provided, and the overflow inlet shall be set at or below the maximum permitted controlled ponding depth so that the roof cannot pond beyond its structural capacity.
−
−# Hangers, Supports, and Expansion
−
−## General Requirements
−
−All storm piping shall be supported continuously so that it cannot sag, deflect, or move under the weight of the pipe, the water it carries, and construction loads. Piping shall not rely on adjacent pipe, conduit, ductwork, or building insulation for support, and shall not be supported by the roof drain. Hangers and supports shall conform to MSS SP-58 for materials and design and shall be selected and spaced in accordance with MSS SP-69. Field-fabricated hangers are not permitted.
−
−## Maximum Hanger Spacing
−
−```datasheet
−label: Cast Iron Storm Pipe Hanger Spacing
−type: select
−unit: ft on center
−options:
− - "5 ft on center, plus at each joint and coupling"
− - "At each joint and coupling, plus at midspan of lengths exceeding 5 ft"
− - "Per drawings"
−default: "5 ft on center, plus at each joint and coupling"
−```
−
−Cast iron storm conductors — both hubless and hub-and-spigot — shall be supported at every coupling and at not more than 5-foot intervals between couplings. Supporting at every joint prevents the joint from experiencing a bending moment from span loads, which over time would work the coupling gasket loose under the cyclic flow loading of storm events.
−
−```datasheet
−label: PVC / Copper Storm Pipe Hanger Spacing
−type: select
−unit: ft on center
−options:
− - "4 ft on center maximum (PVC)"
− - "Per pipe manufacturer for material, size, and temperature"
− - "Per drawings"
−default: "4 ft on center maximum (PVC)"
−```
−
−PVC storm conductors shall be supported at not more than 4-foot intervals and shall not be cinched tightly against the pipe wall; the hanger shall support the pipe without constricting it so that the pipe can move longitudinally as it expands and contracts with temperature. Copper conductors shall be supported per MSS SP-69 for the tube size, with isolation at the hanger to prevent galvanic corrosion.
−
−## Vertical Leader Support
−
−Vertical leaders shall be supported at the base of each leader and at each floor penetration with riser clamps sized for the pipe. The leader support at each floor shall transfer the leader weight to the building structure, not to the roof drain above or to the horizontal piping below.
−
−```datasheet
−label: Vertical Leader Support
−type: radio
−options:
− - "Riser clamp below each floor slab"
− - "Riser clamp through floor sleeve with clamping collar"
− - "Per drawings"
−default: "Riser clamp below each floor slab"
−```
−
−## Thermal Expansion
−
−Long vertical leaders and long horizontal runs are subject to thermal movement from the temperature difference between cold rainwater and warm building air, and from solar-warmed roof water entering a cool conductor. Where the leader length, the pipe material, and the temperature range produce calculated movement exceeding the capacity of the joints and supports, an expansion joint or an engineered offset shall be provided. PVC and copper conductors move substantially more than cast iron for a given temperature change; expansion provisions shall be evaluated for plastic and copper leaders taller than the height at which the calculated movement exceeds the joint and hanger tolerance.
−
−```datasheet
−label: Vertical Leader Expansion Provision
−type: radio
−options:
− - "None required (cast iron, within joint and support tolerance)"
− - "Expansion joint at leader base or as indicated"
− - "Engineered offset / expansion loop per drawings"
− - "Per drawings"
−default: "None required (cast iron, within joint and support tolerance)"
−```
−
−## Seismic Restraint
−
−Where the project is located in a seismic design category requiring seismic restraint of nonstructural systems, lateral bracing and longitudinal restraint for the storm piping shall be designed and installed per the adopted building code and the contract documents. The Contractor shall not proceed with seismic restraint installation without reviewed shop drawings prepared by or reviewed by a licensed structural engineer.
−
−# Condensation Insulation
−
−Horizontal storm conductors, roof drain bodies, and roof drain sumps within conditioned or occupied spaces shall be insulated to prevent condensation. Cold rainwater entering a warm, humid building cools the pipe wall and the drain body below the dew point, and uninsulated storm piping sweats heavily during and after rainfall, dripping onto ceilings, finishes, and equipment below. The drain body and the first portion of the leader are the worst offenders because the drain is in direct contact with cold roof water and is often located above finished, occupied space.
−
−```datasheet
−label: Condensation Insulation Extent
−type: select
−options:
− - "Roof drain bodies and all horizontal conductors in occupied / conditioned spaces"
− - "All storm conductors, horizontal and vertical, in occupied / conditioned spaces"
− - "Roof drain bodies and sumps only"
− - "Per drawings"
−default: "Roof drain bodies and all horizontal conductors in occupied / conditioned spaces"
−```
−
−Insulation thickness, material, and vapor-barrier jacketing shall comply with [[sync/plumbing-insulation]]. At minimum, horizontal conductors and drain bodies in occupied spaces shall be insulated with not less than 1 inch of insulation with a continuous vapor barrier; the vapor barrier is essential, because insulation without a sealed vapor barrier allows humid air to reach the cold pipe and condense inside the insulation, which is worse than no insulation at all. Vertical leaders concealed in chases that are not air-conditioned generally do not require condensation insulation, but the Contractor shall insulate any conductor passing through a humid occupied space.
−
−# Installation
−
−## Drain Setting and Roof Coordination
−
−Roof drains shall be set at the roof low points indicated, with the body flange in the plane of the sump or deck so that the membrane flashing clamp finishes flush at the membrane. Drains shall be set and secured to the structure before the membrane is installed, and the flashing clamp shall be tightened only after the roofing contractor has dressed the membrane into the drain. The Contractor shall verify that the roof slope-to-drain shown on [[drawing: the roof plan]] actually directs water to each drain; a drain set high relative to its surrounding roof leaves a permanent puddle and is a chronic complaint and a ponding-load source.
−
−## Connection of Leader to Drain
−
−The leader shall be connected to the drain outlet with the joint type matching the drain outlet and the leader material. The connection shall be made so that the drain is not supporting the weight of the leader; the leader shall be independently supported within the distance required by the hanger spacing of its material. The connection shall be completed and tested before the drain area is concealed by ceiling construction.
−
−## Horizontal Piping Slope
−
−Horizontal storm drainage piping shall be installed at a uniform slope in the direction of flow without dips, sags, or reverse grades, at not less than the slope used in the sizing calculation. Slope shall be verified during installation using a level on each pipe section; visual inspection alone is not sufficient.
−
−```datasheet
−label: Horizontal Storm Pipe Slope
−type: select
−unit: in/ft
−drawing_ref: true
−options:
− - "1/8 inch per foot (1 percent)"
− - "1/4 inch per foot (2 percent)"
− - "Per drawings"
−default: "1/8 inch per foot (1 percent)"
−```
−
−The minimum slope for horizontal storm piping is 1/8 inch per foot for typical pipe sizes; the pipe must be sized for the slope actually installed, because a flatter slope carries less flow at the same pipe size. Where greater slope can be achieved without conflict it is preferred for self-cleaning velocity, but the slope used must match the slope assumed in the sizing calculation.
−
−## Cleanouts
−
−Cleanouts shall be provided at the base of each leader, at each change of horizontal direction greater than 45 degrees, and at intervals not exceeding 100 feet along horizontal runs, accessible without removing permanent construction. A cleanout at the base of each vertical leader is essential because the base of the leader is where debris washed off the roof collects and where blockages form.
−
−```datasheet
−label: Cleanout at Base of Each Leader
−type: radio
−options:
− - "Required at base of every leader"
− - "Per drawings"
−default: "Required at base of every leader"
−```
−
−## Penetrations and Fire Stopping
−
−Pipes penetrating floor slabs and rated walls shall be sleeved and, in fire-rated assemblies, fire-stopped with a listed firestop system appropriate to the pipe material and the assembly rating. Plastic conductors penetrating fire-rated assemblies shall be fire-stopped with a listed intumescent system tested for plastic pipe in the applicable assembly.
−
−```datasheet
−label: Fire-Rated Penetration Firestop (Plastic Pipe)
−type: radio
−options:
− - "Listed intumescent collar / wrap"
− - "Listed intumescent sealant with mineral wool backer"
− - "Per UL or FM listed assembly as specified on drawings"
−default: "Listed intumescent collar / wrap"
−```
−
−## Connection to the Building Storm Drain and Site System
−
−The horizontal storm piping shall connect to the building storm drain and exit the building to the site storm system at the point indicated on [[drawing: the plumbing and civil drawings]]. The connection shall use a listed transition fitting appropriate to the materials joined. The site storm drainage system beyond the building connection is outside the scope of this standard and is governed by [[sync/storm-drainage]]; the Contractor shall coordinate the connection point and invert elevation with the site utility scope.
−
−# Testing
−
−## General
−
−The storm drainage piping shall be tested after rough-in is complete and before any piping is concealed by insulation, finishes, or fire-rated construction. No piping shall be covered or enclosed before the applicable test has been completed and accepted. Tests shall be performed in the presence of the Engineer's inspector and, where required, the building department inspector. Any portion of the system that shows leakage or loss of test head shall be repaired and re-tested until it demonstrates compliance.
−
−## Water Test
−
−```datasheet
−label: Storm Piping Test Method
−type: radio
−options:
− - "Water test (10-foot head per IPC Section 312)"
− - "Air pressure test (5 psi / 15 minutes)"
−default: "Water test (10-foot head per IPC Section 312)"
−```
−
−For the water test, all openings shall be plugged and the section filled with water to a point not less than 10 feet above the lowest fitting in the section, or to the top of the leader if shorter, and held for not less than 15 minutes with no visible leakage. The water test makes leaks immediately visible and is the preferred acceptance method; air testing can mask slow leaks that the water column reveals.
−
−## Air Test
−
−Where a water test cannot be performed due to freezing temperatures or structural loading limits, an air pressure test may be substituted. The system shall be plugged and pressurized to 5 psi and held for not less than 15 minutes with no pressure loss observed on a calibrated gauge. The Contractor shall confirm that all test plugs are rated and restrained for the test pressure before pressurizing; air testing of PVC pipe is discouraged because PVC can shatter under pressure if it contains a defect.
−
−## Roof Flood Test Coordination
−
−The watertightness of the roof drain flashing-clamp assembly is verified by the roof flood test or other membrane watertightness test performed under [[sync/membrane-roofing]], not by the piping test. The Contractor shall coordinate with the roofing trade so that the drain and clamp are complete and the leader is plugged or capped to allow the roof to be flooded for the membrane test, and shall confirm no leakage occurs at the drain clamp interface during that test.
−
−## Test Reporting
−
−The Contractor shall maintain a test log recording each test section, the date, the test method, the inspector present, the head or pressure at the start and end of the hold period, and the pass/fail determination, and shall submit the log as part of the closeout package.
−
−# Identification and Labeling
−
−Storm drainage piping shall be identified in accessible locations so that maintenance personnel can distinguish storm piping from sanitary waste, domestic water, and other systems. Piping in concealed spaces and mechanical rooms shall be marked with pipe markers conforming to ASME A13.1 indicating the contents (STORM or RAINWATER) and the direction of flow on horizontal lines, at spacing not greater than 25 feet in straight runs, at each change of direction, at each side of wall and floor penetrations, and at each cleanout.
−
−```datasheet
−label: Pipe Marker Scheme (Storm)
−type: radio
−options:
− - "Green background, white text (ASME A13.1 — drains)"
− - "Custom scheme per owner's color-coding standard"
−default: "Green background, white text (ASME A13.1 — drains)"
−```
−
−# Delivery, Storage, and Handling
−
−Pipe, fittings, and drains shall be delivered in the manufacturer's original packaging with identification markings intact, and inspected on delivery for cracks, spalled ends, damaged hubs, and deformed sockets; damaged material shall be returned and not installed. Pipe shall be stored on a flat surface supported continuously along its length. Plastic pipe shall be stored out of direct sunlight, as UV exposure degrades PVC. Roof drains shall be stored with domes and clamp rings kept with their bodies so that matched, listed assemblies are not mixed across drain series. Solvent cement and primer shall be stored cool, away from heat sources, and not used past the shelf-life date.
−
−# Warranty
−
−The Contractor shall warrant all materials and installation covered by this standard against defects in workmanship and against leakage for the project warranty period following substantial completion. The warranty shall cover all joints, connections, hangers, supports, drain assemblies, and the watertightness of the drain flashing-clamp interface to the extent it is within the plumbing scope.
−
−```datasheet
−label: Installation Warranty Period
−type: select
−options:
− - "1 year from substantial completion"
− - "2 years from substantial completion"
−default: "1 year from substantial completion"
−```
−
−Manufacturer warranties for roof drains and specialty drainage products shall be passed through to the Owner as part of the closeout documentation. The warranty shall not limit the Contractor's obligation to comply with all applicable code requirements and the requirements of this standard; a system that does not leak but was installed with an undersized or non-independent secondary system, incorrect slopes, or inadequate supports shall be corrected at the Contractor's expense if deficiencies are discovered within the warranty period.
+---
+title: Roof Drainage
+category: Plumbing
+toc_depth: 3
+description: >
+ When to use: Roof drainage systems on and within the building, including primary roof drains, the required secondary (overflow) drainage by overflow roof drains or overflow scuppers, vertical rainwater leaders and conductors, and horizontal storm drainage piping within the building from each roof drain to the point of connection with the site storm drainage system. Covers rainfall-rate-based sizing, drain types (roof, overflow, deck, balcony, planter, and area drains), controlled-flow roof drainage, drain bodies with domes and strainers, flashing- and membrane-clamp integration with the roofing, piping materials, joining, hangers and supports, expansion provisions, and condensation insulation of conductors. Applicable to commercial, institutional, and industrial buildings with low-slope and steep-slope roofs.
+ Not intended for: Site and underground storm drainage outside the building from the point of connection onward, including catch basins, manholes, detention, and outfalls (see [[sync/storm-drainage]]); sanitary drain, waste, and vent piping (see [[sync/sanitary-waste-and-vent-piping]]); gutters and downspouts that are part of the roofing or sheet-metal scope (see [[sync/membrane-roofing]]); the roof membrane, membrane flashing, and roof insulation themselves (see [[sync/membrane-roofing]]); foundation and subsurface drainage; rainwater harvesting and cistern storage systems; and siphonic roof drainage systems, which require manufacturer-engineered design beyond the gravity-flow scope of this standard.
+---
+
+# Scope {toc}
+
+## This standard covers the design coordination, material selection, fabrication, installation, testing, and acceptance of roof drainage systems on and within the building. {note}
+## The scope encompasses primary roof drains and their bodies, domes, strainers, and flashing-clamp assemblies; the secondary (overflow) drainage system required to protect the structure when the primary system is blocked, provided either as overflow roof drains or as overflow scuppers; the vertical rainwater leaders and conductors that carry roof flow downward through the building; and the horizontal storm drainage piping within the building from the base of each leader to the point of connection with the site storm drainage system. {note}
+
+## Roof drainage is a life-safety scope, not merely a plumbing convenience — a blocked or undersized primary system with no functioning secondary system allows water to pond, and ponded water is one of the heaviest live loads a roof can experience; progressive ponding has collapsed roofs that were otherwise structurally sound. {note}
+
+## The secondary drainage system is required to be sized and routed independently of the primary system, on the assumption that the primary system is completely blocked.
+
+## Where the building storm drain exits the building and connects to the site storm system, the transition point shall be as indicated on [[drawing: the plumbing and civil drawings]] and the downstream system is governed by [[sync/storm-drainage]].
+
+## The roof membrane, membrane base flashing, tapered roof insulation, and roof slope-to-drain are part of the roofing scope and are governed by [[sync/membrane-roofing]]; this standard governs only the drain components that penetrate and clamp to the roof assembly and the piping below.
+
+## Condensation insulation of conductors and drain bodies shall be coordinated with [[sync/plumbing-insulation]].
+
+# Referenced Standards {toc}
+
+## Materials, equipment, and installation shall comply with the latest adopted edition of the following standards and codes unless a specific year is cited elsewhere in the contract documents.
+
+| Standard | Title |
+|----------|-------|
+| IPC | International Plumbing Code (Chapter 11 — Storm Drainage) |
+| UPC | Uniform Plumbing Code (Chapter 11 — Storm Drainage) |
+| IBC | International Building Code (Section 1503.4 — Roof Drainage; Section 1611 — Rain Loads) |
+| ASME A112.6.4 | Roof, Deck, and Balcony Drains |
+| ASME A112.6.3 | Floor and Trench Drains (area and deck drains connected to storm system) |
+| ASME A112.21.2M | Roof Drains (legacy reference; superseded by A112.6.4) |
+| ASTM A74 | Standard Specification for Cast Iron Soil Pipe and Fittings (hub and spigot) |
+| ASTM A888 | Standard Specification for Hubless Cast Iron Soil Pipe and Fittings for Sanitary and Storm Drain, Waste, and Vent Piping Applications |
+| CISPI 301 | Standard Specification for Hubless Cast Iron Soil Pipe and Fittings for Sanitary and Storm Drain, Waste, and Vent Piping Applications |
+| CISPI 310 | Specification for Coupling for Use in Connection with Hubless Cast Iron Soil Pipe and Fittings |
+| ASTM C1277 | Standard Specification for Shielded Couplings Joining Hubless Cast Iron Soil Pipe and Fittings |
+| ASTM C564 | Standard Specification for Rubber Gaskets for Cast Iron Soil Pipe and Fittings |
+| ASTM D2665 | Standard Specification for Poly(Vinyl Chloride) (PVC) Plastic Drain, Waste, and Vent Pipe and Fittings |
+| ASTM D2564 | Standard Specification for Solvent Cements for Poly(Vinyl Chloride) (PVC) Plastic Pipe and Fittings |
+| ASTM F656 | Standard Specification for Primers for Use in Solvent Cement Joints of PVC Plastic Pipe and Fittings |
+| ASTM B306 | Standard Specification for Copper Drainage Tube (DWV) |
+| MSS SP-58 | Pipe Hangers and Supports — Materials, Design and Manufacture |
+| MSS SP-69 | Pipe Hangers and Supports — Selection and Application |
+| ASME A13.1 | Scheme for the Identification of Piping Systems |
+| NSF/ANSI 14 | Plastics Piping System Components and Related Materials |
+
+## Where the contract documents or a referenced standard conflicts with the adopted building or plumbing code, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
+
+## Where the project is located in a jurisdiction that has adopted the Uniform Plumbing Code rather than the International Plumbing Code, references to IPC chapter and section numbers shall be understood to refer to the equivalent UPC provisions.
+
+## The Contractor shall confirm the adopted edition and any local amendments with the Authority Having Jurisdiction prior to submitting the permit application.
+
+# Submittals {toc}
+
+## Action Submittals {toc}
+
+### Contractor shall submit the following for the Engineer's review and comment prior to fabrication, procurement, or installation of any portion of the work:
+
+- Product data for all roof drains, overflow roof drains, deck drains, balcony drains, planter drains, and area drains, including the drain body material, outlet size and type, dome or strainer type and free area, flashing-clamp / gravel-guard configuration, underdeck clamp, sump receiver, and any extension or expansion accessories, with confirmation of compliance with ASME A112.6.4
+- Product data for all piping materials, including pipe and fittings conforming to the applicable ASTM or CISPI standard, with confirmation of the standard designation and applicable weight or schedule class
+- Product data for shielded couplings for hubless cast iron pipe, including the manufacturer's published torque specification and listing information
+- Roof drainage sizing calculations showing the design rainfall rate used, the roof area tributary to each drain, the resulting required drain, leader, and horizontal pipe sizes, and the independent sizing of the secondary (overflow) system assuming the primary system is fully blocked
+- Coordination drawings showing each drain location relative to the structural roof framing, the roof slope-to-drain, the membrane flashing clamp interface, and the leader routing through the building
+- Product data for pipe hangers, supports, riser clamps, and seismic restraints, including the manufacturer's load tables for the sizes and pipe materials specified
+- Condensation insulation product data and the extent of insulated piping, coordinated with [[sync/plumbing-insulation]]
+- Penetration details for all fire-rated floor and wall penetrations, with fire-stop product data and listed assembly numbers
+
+```datasheet
+label: Action Submittals Required
+type: checkbox
+options:
+ - "Roof drain, overflow drain, and specialty drain product data (ASME A112.6.4)"
+ - "Pipe and fitting product data"
+ - "Shielded coupling product data with torque specification"
+ - "Roof drainage sizing calculations (primary and independent secondary)"
+ - "Drain location and leader routing coordination drawings"
+ - "Hanger, support, and seismic restraint product data with load tables"
+ - "Condensation insulation product data and extent"
+ - "Fire-stop penetration details"
+default: "Roof drainage sizing calculations (primary and independent secondary)"
+```
+
+### The Contractor shall submit the action submittals listed above prior to fabrication, procurement, or installation of any portion of the work.
+
+### No substitutions for specified materials shall be used until the substitution has been reviewed and accepted in writing.
+
+## Closeout Submittals {toc}
+
+### Contractor shall provide the following at substantial completion before the roof drainage system is accepted:
+
+- As-built drawings showing the installed drain locations, leader routing, horizontal piping invert elevations at cleanouts and connection points, and any deviations from the contract documents
+- Field test reports for all water and air tests performed on the storm piping, signed by the testing technician, with pass/fail determination and corrective actions taken
+- Manufacturer's warranty documentation for roof drains and specialty drainage products
+- Operation and maintenance data covering drain dome and strainer cleaning intervals and secondary-system inspection recommendations
+
+```datasheet
+label: Required Closeout Submittals
+type: checkbox
+options:
+ - "As-built drawings (drain locations, leader routing, invert elevations, deviations)"
+ - "Field test reports for water and air tests, signed, with pass/fail determination"
+ - "Manufacturer's warranty documentation for roof drains and specialty products"
+ - "Operation and maintenance data (cleaning intervals, secondary-system inspection)"
+default: [As-built drawings (drain locations, leader routing, invert elevations, deviations), Field test reports for water and air tests, signed, with pass/fail determination, Manufacturer's warranty documentation for roof drains and specialty products, Operation and maintenance data (cleaning intervals, secondary-system inspection)]
+```
+
+### The Contractor shall provide the closeout submittals listed above at substantial completion before the roof drainage system is accepted.
+
+# Quality Assurance {toc}
+
+## Installer Qualifications {toc}
+
+### All roof drainage piping shall be installed by a licensed plumbing contractor and by journeymen or apprentice plumbers working under the direct supervision of a licensed journeyman.
+
+### The installing contractor shall have verifiable experience in commercial storm drainage installation on at least three projects of comparable size and complexity within the preceding five years.
+
+## Listing and Marking {toc}
+
+### All drains, pipe, fittings, and couplings shall be listed and marked by a nationally recognized testing laboratory for the applicable product standard.
+
+### Roof drains shall bear the ASME A112.6.4 designation and the manufacturer's identification.
+
+### Cast iron soil pipe shall be marked with the applicable standard designation (ASTM A74 or ASTM A888 / CISPI 301), the pipe weight class, and the manufacturer's identification.
+
+### PVC pipe shall carry the NSF/ANSI 14 listing mark.
+
+### Unlisted or unmarked pipe, fittings, and drains shall be rejected and removed from the project regardless of documentation provided by the supplier.
+
+## Coordination with the Roofing Trade {toc}
+
+## The roof drain flashing-clamp interface is a shared responsibility between the plumbing and roofing trades, and the most common source of roof leaks at drains is a poorly coordinated clamp installation. {note}
+
+### The Contractor shall coordinate the setting elevation of each drain body, the sequence of membrane installation and clamp-ring tightening, and the responsibility for the membrane target sheet or flashing collar with the roofing contractor before any drain is set.
+
+### The roof drain body shall be set so that its flange sits in the plane of the roof structural deck or sump, with the membrane clamping ring positioned to clamp the roofing membrane uniformly to the drain flange.
+
+### Coordination shall conform to the requirements of [[sync/membrane-roofing]] for the membrane-side detailing.
+
+## Regulatory Inspection Hold Points {toc}
+
+### The Contractor shall schedule inspections by the Authority Having Jurisdiction for the rough storm piping before concealment.
+
+### No portion of the storm drainage system shall be concealed before the applicable rough plumbing inspection has been completed and released.
+
+# Storm Drainage Design Basis {toc}
+
+## Design Rainfall Rate {toc}
+
+```datasheet
+label: Design Rainfall Rate (100-year, 1-hour)
+type: range
+unit: in/hr
+drawing_ref: true
+options:
+ min: 1
+ max: 10
+ setpoints: [2, 3, 4, 5, 6, 7, 8]
+default: 4
+```
+
+### The size of all roof drains, leaders, conductors, and horizontal storm piping shall be based on the local design rainfall rate.
+
+### Unless the contract documents specify otherwise, the design rainfall rate shall be the 100-year, 1-hour rainfall rate for the project location, expressed in inches per hour, taken from the rainfall figures in IPC Section 1106 or from approved local weather data.
+
+### The design rainfall rate is a project-specific value and shall be confirmed against the geographic location before sizing.
+
+### The default value of 4 in/hr shall not be used without confirming the value for the actual project location, because under-sizing the drainage system to an incorrect rainfall rate defeats the entire purpose of the design.
+
+### The rainfall rate used shall be recorded on the sizing calculation submittal.
+
+## The 100-year, 1-hour rainfall rate varies widely across the United States, from roughly 2 in/hr in the arid interior west to 8 in/hr or more along the Gulf Coast and parts of the southeast; the default of 4 in/hr is representative of much of the central and eastern United States. {note}
+
+## Tributary Roof Area {toc}
+
+### Each roof drain shall be assigned the roof area that drains to it, including any adjacent vertical wall area that sheds water onto the roof in accordance with the adopted code's vertical-wall area provisions.
+
+### Tributary areas, drain locations, and roof slope-to-drain shall be [[drawing: as indicated on the roof plan and the plumbing roof drainage plan]].
+
+### The Contractor shall verify that the drain locations shown produce the tributary areas assumed in the sizing calculations and shall report any discrepancy to the Engineer of Record before installation.
+
+## Primary System Sizing {toc}
+
+```datasheet
+label: Primary Leader and Pipe Sizes
+type: select
+drawing_ref: true
+options:
+ - "2 inch"
+ - "3 inch"
+ - "4 inch"
+ - "5 inch"
+ - "6 inch"
+ - "8 inch"
+ - "10 inch"
+ - "12 inch"
+ - "Per drawings"
+default: "Per drawings"
+```
+
+### Vertical leaders, conductors, and horizontal storm drains for the primary system shall be sized for the design rainfall rate and the tributary area in accordance with the sizing tables of the adopted plumbing code (IPC Section 1106 or the UPC equivalent).
+
+### No reduction in pipe size shall be made in the direction of flow.
+
+### Horizontal storm piping shall be sized for its installed slope; flatter slopes require larger pipe to carry the same flow.
+
+## Secondary (Overflow) System Sizing — Independent of Primary {toc}
+
+```datasheet
+label: Secondary (Overflow) Drainage Method
+type: radio
+options:
+ - "Overflow roof drains with independent piping to a conspicuous discharge"
+ - "Overflow scuppers through the parapet wall"
+ - "Combination — overflow drains at interior low points, scuppers at parapet"
+ - "Per drawings"
+default: "Overflow roof drains with independent piping to a conspicuous discharge"
+```
+
+### A secondary (overflow) drainage system shall be provided wherever the roof construction extends above the roof surface in a manner that would entrap water if the primary drains became blocked.
+
+### The secondary system shall be sized for the full design rainfall rate on the assumption that the primary drainage system is completely blocked.
+
+### The flow capacity of the primary system shall not be credited when sizing the secondary system.
+
+## This is the single most important requirement in this standard: the secondary system exists to protect the structure from ponding collapse when the primary system fails, and crediting the primary capacity would defeat that protection. {note}
+
+## The choice between overflow roof drains and overflow scuppers is driven by roof geometry — scuppers are simple, reliable, and require no additional interior piping, preferred wherever a parapet wall is adjacent to the roof low point; overflow drains are required where the low point is remote from any exterior wall, the parapet is too high to scupper economically, or the architecture does not permit a parapet penetration, but carry the disadvantage of a complete independent piping system. {note}
+
+# Roof Drains {toc}
+
+## General {toc}
+
+### Roof drains shall conform to ASME A112.6.4 and shall be of the type, body material, outlet size, and accessory configuration indicated.
+
+### Each drain shall be furnished with a body, a removable dome or strainer, a combination membrane flashing clamp and gravel guard, and the deck-attachment and extension accessories appropriate to the roof assembly.
+
+### Drain types, sizes, and locations shall be [[drawing: as indicated on the plumbing roof drainage plan and the roof drain schedule]].
+
+## Drain Body Material {toc}
+
+```datasheet
+label: Roof Drain Body Material
+type: radio
+options:
+ - "Cast iron with corrosion-resistant coating"
+ - "Cast iron with epoxy or PVC coating (corrosive or coastal environments)"
+ - "Cast aluminum (weight-sensitive applications)"
+ - "Per drawings"
+default: "Cast iron with corrosion-resistant coating"
+```
+
+## Coated cast iron is the standard drain body material for commercial and institutional roofs — its mass and rigidity hold the flashing-clamp interface flat under thermal cycling, and the coating protects against the corrosive concentration of roof runoff; cast aluminum is used where roof structural weight governs or in lightweight decks but is less tolerant of abrasion and impact; epoxy- or PVC-coated cast iron is warranted in coastal salt-air environments and where the roof receives chemical exhaust. {note}
+
+## Drain Outlet Type {toc}
+
+```datasheet
+label: Roof Drain Outlet Connection
+type: radio
+options:
+ - "No-hub outlet (hubless cast iron coupling connection)"
+ - "Inside-caulk outlet (hub-and-spigot)"
+ - "Threaded outlet"
+ - "Per drawings"
+default: "No-hub outlet (hubless cast iron coupling connection)"
+```
+
+### The drain outlet shall match the leader piping material and joining method.
+
+## No-hub outlets connecting to hubless cast iron couplings are the most common configuration in modern commercial construction and allow the drain to be set and the leader connected without disturbing the membrane clamp once it is tightened. {note}
+
+## Dome and Strainer {toc}
+
+```datasheet
+label: Primary Roof Drain Dome / Strainer Type
+type: select
+options:
+ - "Cast iron dome strainer (low-slope roof, non-traffic)"
+ - "Polyethylene / polymer dome strainer (low-slope roof, non-traffic)"
+ - "Aluminum dome strainer (low-slope roof, non-traffic)"
+ - "Flat secured grate (deck, balcony, walkable surfaces)"
+ - "Per drawings"
+default: "Cast iron dome strainer (low-slope roof, non-traffic)"
+```
+
+### Each primary roof drain on a low-slope roof shall be furnished with a removable dome-type strainer extending not less than 4 inches above the roof surface, with a free inlet area not less than 1.5 times the area of the drain outlet so that the strainer cannot become the flow-limiting element when partially blocked by debris.
+
+### Drains on gravel-surfaced or ballasted roofs shall include a gravel guard or gravel stop integral with the flashing clamp to keep ballast out of the drain.
+
+### Drains in walkable deck and balcony locations shall use a flat, secured grate rated for foot traffic rather than a dome, and shall comply with the slip-resistance and accessibility requirements applicable to the walking surface.
+
+### The dome shall be removable for cleaning without tools where the roof is regularly maintained by the Owner's personnel.
+
+## The dome strainer's purpose is to keep leaves, debris, and ballast out of the leader while presenting enough free area that partial blockage does not choke the drain; polymer domes are lighter and corrosion-resistant but can become brittle and crack under cold-weather impact, while cast iron and aluminum domes are more durable for roofs that see regular foot traffic. {note}
+
+## Flashing Clamp and Membrane Integration {toc}
+
+### Each drain shall be furnished with a combination membrane flashing clamp ring and gravel guard that clamps the roofing membrane uniformly to the drain body flange.
+
+### The clamping ring shall be secured with the manufacturer's bolts at the spacing indicated in the drain's listing, tightened uniformly in a cross pattern so that the membrane is compressed evenly around the full circumference without wrinkles or gaps.
+
+### The membrane-side detailing — the target sheet, the stripping, and the membrane termination at the clamp — shall be installed by the roofing trade in accordance with [[sync/membrane-roofing]].
+
+### The plumbing Contractor shall not tighten the clamp ring until the roofing membrane has been dressed into the drain and the roofing contractor confirms the membrane is ready to be clamped.
+
+## Underdeck Clamp and Deck Attachment {toc}
+
+```datasheet
+label: Drain Deck Attachment
+type: radio
+options:
+ - "Underdeck clamp to structural deck"
+ - "Set in poured concrete roof sump"
+ - "Sump receiver / sump pan for tapered insulation sump"
+ - "Per drawings"
+default: "Underdeck clamp to structural deck"
+```
+
+### Where the drain is set in a structural deck without a poured sump, the drain shall be furnished with an underdeck clamp that secures the drain body to the underside of the deck and transfers the drain weight and connected piping load to the structure rather than to the membrane or the leader.
+
+### The drain shall not be supported by the leader piping alone.
+
+### Where the drain is set in a poured concrete sump, the drain flange shall bear on the sump and the body shall be secured against rotation before the membrane is clamped.
+
+## Extension and Adjustment {toc}
+
+### Where the drain body must accommodate the thickness of rigid roof insulation between the structural deck and the membrane, a drain extension (sump extender) or an adjustable extension collar shall be provided so that the membrane flashing clamp finishes flush at the membrane plane while the drain body is anchored at the deck.
+
+### The extension shall be of the same manufacturer and series as the drain body to ensure a sealed, listed assembly.
+
+# Overflow (Secondary) Drainage {toc}
+
+## Overflow Roof Drains {toc}
+
+```datasheet
+label: Overflow Roof Drain Inlet Dam Height
+type: range
+unit: in
+options:
+ min: 2
+ max: 4
+ setpoints: [2, 3, 4]
+default: 2
+```
+
+### Where overflow roof drains are used, each overflow drain shall be a roof drain conforming to ASME A112.6.4 with a water dam (standpipe collar) at its inlet so that the overflow inlet flow line is set not less than 2 inches above the adjacent roof low point.
+
+### Overflow drains shall be of the same body material and dome type as the primary drains they back up.
+
+### Where a taller dam is specified, the dam height plus the head required to drive the design flow through the overflow drain shall not exceed the ponding depth the roof structure is designed to carry.
+
+### The dam height shall be coordinated with the structural rain-load analysis under IBC Section 1611.
+
+## The 2-inch dam ensures that the overflow drain remains dry during normal operation and admits water only when the depth on the roof rises above the level at which the primary drain should have carried it away — that is, only when the primary drain is blocked; a taller dam may be used where the roof structure can tolerate greater ponding depth to keep the overflow inactive under more frequent storms. {note}
+
+## Overflow Drain Piping — Independent and Conspicuous Discharge {toc}
+
+```datasheet
+label: Overflow Drain Discharge Location
+type: select
+drawing_ref: true
+options:
+ - "Through exterior wall to splash block at grade (conspicuous)"
+ - "To downspout boot at grade, separate from primary downspouts"
+ - "To a visible point above grade at a building entrance or occupied area"
+ - "Per drawings"
+default: "Through exterior wall to splash block at grade (conspicuous)"
+```
+
+### The piping serving overflow roof drains shall be entirely independent of the primary roof drain piping system from the drain to the point of discharge; the two systems shall not be combined at any point.
+
+### The overflow piping shall discharge above grade at a location that is normally observed by building occupants or maintenance personnel — typically to a splash block, a downspout boot, or a wall outlet not more than the code-permitted height above grade.
+
+### Overflow piping shall not be tied into the building storm drain, the site storm system, or any concealed discharge where occupants would not see it.
+
+## A conspicuous discharge is required so that flow from the overflow system is immediately visible as a signal that the primary system has failed; a secondary system discharging to the same concealed point as the primary gives no warning, and a blockage common to both (a clogged building drain) would disable both at once. {note}
+
+## Overflow Scuppers {toc}
+
+```datasheet
+label: Overflow Scupper Minimum Opening Height
+type: range
+unit: in
+options:
+ min: 4
+ max: 12
+ setpoints: [4, 6, 8]
+default: 4
+```
+
+### Where overflow scuppers are used, each scupper shall be an opening through the parapet or perimeter wall with the inlet flow line set not more than 2 inches above the adjacent roof low point and a clear opening height of not less than 4 inches.
+
+### The scupper width shall be sized to carry the design rainfall flow from its tributary area at the head available within the roof structure's permitted ponding depth.
+
+### Where a scupper backs up a single primary roof drain, its opening shall be not less than the circumference of a primary roof drain sized for the same area.
+
+### Scuppers shall be furnished with a sheet-metal or membrane-flashed sleeve through the wall and an exterior face that discharges clear of the wall to a conspicuous point.
+
+### Scupper sleeves and their flashing shall be coordinated with the membrane and sheet-metal work under [[sync/membrane-roofing]].
+
+## The 4-inch minimum opening height is a code floor; in practice the opening is sized for flow, and a wider, taller opening is often required to pass the design flow at the limited head the roof structure can tolerate — the scupper is a wall and roofing penetration as much as a drainage device, and a poorly flashed scupper is a chronic leak source. {note}
+
+# Conductors and Storm Piping {toc}
+
+## Conductor and Leader Materials {toc}
+
+```datasheet
+label: Interior Storm Piping Material
+type: radio
+options:
+ - "Hubless cast iron (ASTM A888 / CISPI 301)"
+ - "Hub-and-spigot cast iron (ASTM A74), compression gasket joints"
+ - "Copper DWV (ASTM B306)"
+ - "PVC DWV Schedule 40 (ASTM D2665)"
+ - "Per drawings"
+default: "Hubless cast iron (ASTM A888 / CISPI 301)"
+```
+
+### Conductors (vertical leaders) and horizontal storm drainage piping within the building shall be of the materials indicated.
+
+### Conductor pipe shall not be used as soil, waste, or vent pipe, and soil, waste, or vent pipe shall not be used as a conductor.
+
+### The storm and sanitary systems shall remain separate within the building unless a combined system is specifically permitted by the Authority Having Jurisdiction and indicated on the drawings.
+
+### PVC DWV shall not be used in chases adjacent to occupied spaces where acoustic performance is required, consistent with [[sync/sanitary-waste-and-vent-piping]].
+
+## Hubless cast iron is the preferred material for interior storm conductors for the same reasons it is preferred for sanitary piping: superior noise attenuation, impact resistance, fire resistance, and service life; the acoustic advantage matters because heavy rainfall produces a loud, intermittent rush of water that is objectionable in occupied spaces when carried by thin-wall plastic pipe, while copper DWV suits exposed architectural locations and PVC DWV is acceptable where noise is not a concern and the adopted code permits it. {note}
+
+## Cast Iron — Hubless {toc}
+
+```datasheet
+label: Hubless Cast Iron Weight Class
+type: radio
+options:
+ - "Service weight"
+ - "Extra-heavy weight"
+default: "Service weight"
+```
+
+### Hubless cast iron soil pipe and fittings used as storm conductors shall conform to ASTM A888 or CISPI 301 and shall be joined with shielded couplings conforming to CISPI 310 and ASTM C1277.
+
+### Couplings shall have a stainless steel outer shield, stainless steel worm-drive clamp bands, and a neoprene sleeve gasket, and shall be installed with a calibrated torque wrench set to the coupling manufacturer's published torque.
+
+### Service weight pipe shall be used unless extra-heavy weight is indicated for buried or heavily loaded locations.
+
+## Cast Iron — Hub-and-Spigot {toc}
+
+### Hub-and-spigot cast iron storm conductors shall conform to ASTM A74 and shall be joined with compression rubber gaskets conforming to ASTM C564.
+
+### Lead and oakum caulked joints shall not be used in new construction.
+
+## The compression gasket joint creates a watertight, root-resistant seal and tolerates minor movement without the rigidity of solvent-cemented joints. {note}
+
+## Copper DWV {toc}
+
+### Copper drainage tube shall conform to ASTM B306 (DWV) and shall be joined with cast or wrought copper drainage fittings using lead-free solder or brazing.
+
+### The Contractor shall protect copper conductors from galvanic contact with dissimilar metals at hangers and supports.
+
+## Copper conductors are appropriate for exposed architectural runs and for connection to copper roof drains. {note}
+
+## PVC DWV {toc}
+
+### PVC pipe and fittings used as storm conductors shall conform to ASTM D2665, shall be Schedule 40, and shall carry the NSF/ANSI 14 listing mark.
+
+### PVC shall be joined by the two-step primer-and-solvent-cement method using a primer conforming to ASTM F656 and solvent cement conforming to ASTM D2564.
+
+## The primer is not optional; a joint made without primer does not develop the surface dissolution that creates a true chemical weld. {note}
+
+## Pipe Size Schedule {toc}
+
+### Pipe sizes shall be as indicated on the drawings and shall match the sizing calculations.
+
+### No reduction in pipe size shall be made in the direction of flow.
+
+### The Contractor shall verify that the pipe sizes shown comply with the sizing calculations for the design rainfall rate and tributary areas, and shall report any discrepancy to the Engineer of Record before installation.
+
+# Controlled-Flow Roof Drainage {toc}
+
+## Application {toc}
+
+```datasheet
+label: Controlled-Flow Roof Drainage
+type: radio
+options:
+ - "Not used — conventional free-draining roof drainage"
+ - "Used — controlled-flow primary drainage per drawings and structural analysis"
+default: "Not used — conventional free-draining roof drainage"
+```
+
+### Controlled-flow drainage shall be used only where the contract documents specifically require it, and only where the roof structure has been specifically designed to carry the resulting ponded-water load.
+
+### Controlled-flow drainage shall not be applied to a roof that has not been structurally analyzed for the controlled ponding depth.
+
+## Controlled-flow (restrictive-flow) roof drainage intentionally meters the rate at which rainwater leaves the roof, using the roof itself as temporary detention storage so that the leaders, conductors, and downstream storm system can be smaller than for a conventional free-draining roof — typically required where the site or municipal storm connection has limited capacity and the jurisdiction requires on-roof detention. {note}
+
+## Controlled-Flow Drain Requirements {toc}
+
+### Where controlled-flow drainage is used, each primary drain shall be a controlled-flow roof drain with a calibrated weir or flow-restricting device that limits the discharge rate to the design metered flow at the corresponding head.
+
+### The metered flow rate, the maximum design head (ponding depth) at each drain, and the corresponding structural roof loading shall be [[drawing: as indicated on the plumbing and structural drawings]].
+
+### A secondary (overflow) drainage system sized for the full design rainfall rate with the primary controlled-flow system assumed blocked shall always be provided.
+
+### The overflow inlet shall be set at or below the maximum permitted controlled ponding depth so that the roof cannot pond beyond its structural capacity.
+
+# Hangers, Supports, and Expansion {toc}
+
+## General Requirements {toc}
+
+### All storm piping shall be supported continuously so that it cannot sag, deflect, or move under the weight of the pipe, the water it carries, and construction loads.
+
+### Piping shall not rely on adjacent pipe, conduit, ductwork, or building insulation for support, and shall not be supported by the roof drain.
+
+### Hangers and supports shall conform to MSS SP-58 for materials and design and shall be selected and spaced in accordance with MSS SP-69.
+
+### Field-fabricated hangers are not permitted.
+
+## Maximum Hanger Spacing {toc}
+
+```datasheet
+label: Cast Iron Storm Pipe Hanger Spacing
+type: select
+unit: ft on center
+options:
+ - "5 ft on center, plus at each joint and coupling"
+ - "At each joint and coupling, plus at midspan of lengths exceeding 5 ft"
+ - "Per drawings"
+default: "5 ft on center, plus at each joint and coupling"
+```
+
+```datasheet
+label: PVC / Copper Storm Pipe Hanger Spacing
+type: select
+unit: ft on center
+options:
+ - "4 ft on center maximum (PVC)"
+ - "Per pipe manufacturer for material, size, and temperature"
+ - "Per drawings"
+default: "4 ft on center maximum (PVC)"
+```
+
+### Cast iron storm conductors — both hubless and hub-and-spigot — shall be supported at every coupling and at not more than 5-foot intervals between couplings.
+
+### PVC storm conductors shall be supported at not more than 4-foot intervals and shall not be cinched tightly against the pipe wall; the hanger shall support the pipe without constricting it so that the pipe can move longitudinally as it expands and contracts with temperature.
+
+### Copper conductors shall be supported per MSS SP-69 for the tube size, with isolation at the hanger to prevent galvanic corrosion.
+
+## Supporting cast iron at every joint prevents the joint from experiencing a bending moment from span loads, which over time would work the coupling gasket loose under the cyclic flow loading of storm events. {note}
+
+## Vertical Leader Support {toc}
+
+```datasheet
+label: Vertical Leader Support
+type: radio
+options:
+ - "Riser clamp below each floor slab"
+ - "Riser clamp through floor sleeve with clamping collar"
+ - "Per drawings"
+default: "Riser clamp below each floor slab"
+```
+
+### Vertical leaders shall be supported at the base of each leader and at each floor penetration with riser clamps sized for the pipe.
+
+### The leader support at each floor shall transfer the leader weight to the building structure, not to the roof drain above or to the horizontal piping below.
+
+## Thermal Expansion {toc}
+
+```datasheet
+label: Vertical Leader Expansion Provision
+type: radio
+options:
+ - "None required (cast iron, within joint and support tolerance)"
+ - "Expansion joint at leader base or as indicated"
+ - "Engineered offset / expansion loop per drawings"
+ - "Per drawings"
+default: "None required (cast iron, within joint and support tolerance)"
+```
+
+### Where the leader length, the pipe material, and the temperature range produce calculated movement exceeding the capacity of the joints and supports, an expansion joint or an engineered offset shall be provided.
+
+### Expansion provisions shall be evaluated for plastic and copper leaders taller than the height at which the calculated movement exceeds the joint and hanger tolerance.
+
+## Long vertical leaders and long horizontal runs are subject to thermal movement from the temperature difference between cold rainwater and warm building air, and from solar-warmed roof water entering a cool conductor; PVC and copper conductors move substantially more than cast iron for a given temperature change. {note}
+
+## Seismic Restraint {toc}
+
+### Where the project is located in a seismic design category requiring seismic restraint of nonstructural systems, lateral bracing and longitudinal restraint for the storm piping shall be designed and installed per the adopted building code and the contract documents.
+
+### The Contractor shall not proceed with seismic restraint installation without reviewed shop drawings prepared by or reviewed by a licensed structural engineer.
+
+# Condensation Insulation {toc}
+
+```datasheet
+label: Condensation Insulation Extent
+type: select
+options:
+ - "Roof drain bodies and all horizontal conductors in occupied / conditioned spaces"
+ - "All storm conductors, horizontal and vertical, in occupied / conditioned spaces"
+ - "Roof drain bodies and sumps only"
+ - "Per drawings"
+default: "Roof drain bodies and all horizontal conductors in occupied / conditioned spaces"
+```
+
+## Horizontal storm conductors, roof drain bodies, and roof drain sumps within conditioned or occupied spaces shall be insulated to prevent condensation.
+
+## Insulation thickness, material, and vapor-barrier jacketing shall comply with [[sync/plumbing-insulation]].
+
+## At minimum, horizontal conductors and drain bodies in occupied spaces shall be insulated with not less than 1 inch of insulation with a continuous vapor barrier.
+
+## The Contractor shall insulate any conductor passing through a humid occupied space, although vertical leaders concealed in chases that are not air-conditioned generally do not require condensation insulation.
+
+## Cold rainwater entering a warm, humid building cools the pipe wall and the drain body below the dew point, and uninsulated storm piping sweats heavily during and after rainfall, dripping onto ceilings, finishes, and equipment below; the drain body and the first portion of the leader are the worst offenders because the drain is in direct contact with cold roof water and is often located above finished, occupied space. {note}
+
+## The vapor barrier is essential, because insulation without a sealed vapor barrier allows humid air to reach the cold pipe and condense inside the insulation, which is worse than no insulation at all. {note}
+
+# Installation {toc}
+
+## Drain Setting and Roof Coordination {toc}
+
+### Roof drains shall be set at the roof low points indicated, with the body flange in the plane of the sump or deck so that the membrane flashing clamp finishes flush at the membrane.
+
+### Drains shall be set and secured to the structure before the membrane is installed, and the flashing clamp shall be tightened only after the roofing contractor has dressed the membrane into the drain.
+
+### The Contractor shall verify that the roof slope-to-drain shown on [[drawing: the roof plan]] actually directs water to each drain.
+
+## A drain set high relative to its surrounding roof leaves a permanent puddle and is a chronic complaint and a ponding-load source. {note}
+
+## Connection of Leader to Drain {toc}
+
+### The leader shall be connected to the drain outlet with the joint type matching the drain outlet and the leader material.
+
+### The connection shall be made so that the drain is not supporting the weight of the leader; the leader shall be independently supported within the distance required by the hanger spacing of its material.
+
+### The connection shall be completed and tested before the drain area is concealed by ceiling construction.
+
+## Horizontal Piping Slope {toc}
+
+```datasheet
+label: Horizontal Storm Pipe Slope
+type: select
+unit: in/ft
+drawing_ref: true
+options:
+ - "1/8 inch per foot (1 percent)"
+ - "1/4 inch per foot (2 percent)"
+ - "Per drawings"
+default: "1/8 inch per foot (1 percent)"
+```
+
+### Horizontal storm drainage piping shall be installed at a uniform slope in the direction of flow without dips, sags, or reverse grades, at not less than the slope used in the sizing calculation.
+
+### Slope shall be verified during installation using a level on each pipe section; visual inspection alone is not sufficient.
+
+### The pipe shall be sized for the slope actually installed, because a flatter slope carries less flow at the same pipe size.
+
+## The minimum slope for horizontal storm piping is 1/8 inch per foot for typical pipe sizes; where greater slope can be achieved without conflict it is preferred for self-cleaning velocity, but the slope used must match the slope assumed in the sizing calculation. {note}
+
+## Cleanouts {toc}
+
+```datasheet
+label: Cleanout at Base of Each Leader
+type: radio
+options:
+ - "Required at base of every leader"
+ - "Per drawings"
+default: "Required at base of every leader"
+```
+
+### Cleanouts shall be provided at the base of each leader, at each change of horizontal direction greater than 45 degrees, and at intervals not exceeding 100 feet along horizontal runs, accessible without removing permanent construction.
+
+## A cleanout at the base of each vertical leader is essential because the base of the leader is where debris washed off the roof collects and where blockages form. {note}
+
+## Penetrations and Fire Stopping {toc}
+
+```datasheet
+label: Fire-Rated Penetration Firestop (Plastic Pipe)
+type: radio
+options:
+ - "Listed intumescent collar / wrap"
+ - "Listed intumescent sealant with mineral wool backer"
+ - "Per UL or FM listed assembly as specified on drawings"
+default: "Listed intumescent collar / wrap"
+```
+
+### Pipes penetrating floor slabs and rated walls shall be sleeved and, in fire-rated assemblies, fire-stopped with a listed firestop system appropriate to the pipe material and the assembly rating.
+
+### Plastic conductors penetrating fire-rated assemblies shall be fire-stopped with a listed intumescent system tested for plastic pipe in the applicable assembly.
+
+## Connection to the Building Storm Drain and Site System {toc}
+
+### The horizontal storm piping shall connect to the building storm drain and exit the building to the site storm system at the point indicated on [[drawing: the plumbing and civil drawings]].
+
+### The connection shall use a listed transition fitting appropriate to the materials joined.
+
+### The Contractor shall coordinate the connection point and invert elevation with the site utility scope.
+
+## The site storm drainage system beyond the building connection is outside the scope of this standard and is governed by [[sync/storm-drainage]]. {note}
+
+# Testing {toc}
+
+## General {toc}
+
+### The storm drainage piping shall be tested after rough-in is complete and before any piping is concealed by insulation, finishes, or fire-rated construction.
+
+### No piping shall be covered or enclosed before the applicable test has been completed and accepted.
+
+### Tests shall be performed in the presence of the Engineer's inspector and, where required, the building department inspector.
+
+### Any portion of the system that shows leakage or loss of test head shall be repaired and re-tested until it demonstrates compliance.
+
+## Water Test {toc}
+
+```datasheet
+label: Storm Piping Test Method
+type: radio
+options:
+ - "Water test (10-foot head per IPC Section 312)"
+ - "Air pressure test (5 psi / 15 minutes)"
+default: "Water test (10-foot head per IPC Section 312)"
+```
+
+### For the water test, all openings shall be plugged and the section filled with water to a point not less than 10 feet above the lowest fitting in the section, or to the top of the leader if shorter, and held for not less than 15 minutes with no visible leakage.
+
+## The water test makes leaks immediately visible and is the preferred acceptance method; air testing can mask slow leaks that the water column reveals. {note}
+
+## Air Test {toc}
+
+### Where a water test cannot be performed due to freezing temperatures or structural loading limits, an air pressure test may be substituted.
+
+### The system shall be plugged and pressurized to 5 psi and held for not less than 15 minutes with no pressure loss observed on a calibrated gauge.
+
+### The Contractor shall confirm that all test plugs are rated and restrained for the test pressure before pressurizing.
+
+## Air testing of PVC pipe is discouraged because PVC can shatter under pressure if it contains a defect. {note}
+
+## Roof Flood Test Coordination {toc}
+
+### The Contractor shall coordinate with the roofing trade so that the drain and clamp are complete and the leader is plugged or capped to allow the roof to be flooded for the membrane test, and shall confirm no leakage occurs at the drain clamp interface during that test.
+
+## The watertightness of the roof drain flashing-clamp assembly is verified by the roof flood test or other membrane watertightness test performed under [[sync/membrane-roofing]], not by the piping test. {note}
+
+## Test Reporting {toc}
+
+### The Contractor shall maintain a test log recording each test section, the date, the test method, the inspector present, the head or pressure at the start and end of the hold period, and the pass/fail determination.
+
+### The Contractor shall submit the test log as part of the closeout package.
+
+# Identification and Labeling {toc}
+
+```datasheet
+label: Pipe Marker Scheme (Storm)
+type: radio
+options:
+ - "Green background, white text (ASME A13.1 — drains)"
+ - "Custom scheme per owner's color-coding standard"
+default: "Green background, white text (ASME A13.1 — drains)"
+```
+
+## Storm drainage piping shall be identified in accessible locations so that maintenance personnel can distinguish storm piping from sanitary waste, domestic water, and other systems.
+
+## Piping in concealed spaces and mechanical rooms shall be marked with pipe markers conforming to ASME A13.1 indicating the contents (STORM or RAINWATER) and the direction of flow on horizontal lines, at spacing not greater than 25 feet in straight runs, at each change of direction, at each side of wall and floor penetrations, and at each cleanout.
+
+# Delivery, Storage, and Handling {toc}
+
+## Pipe, fittings, and drains shall be delivered in the manufacturer's original packaging with identification markings intact, and inspected on delivery for cracks, spalled ends, damaged hubs, and deformed sockets.
+
+## Damaged material shall be returned and not installed.
+
+## Pipe shall be stored on a flat surface supported continuously along its length.
+
+## Plastic pipe shall be stored out of direct sunlight, as UV exposure degrades PVC.
+
+## Roof drains shall be stored with domes and clamp rings kept with their bodies so that matched, listed assemblies are not mixed across drain series.
+
+## Solvent cement and primer shall be stored cool, away from heat sources, and not used past the shelf-life date.
+
+# Warranty {toc}
+
+```datasheet
+label: Installation Warranty Period
+type: select
+options:
+ - "1 year from substantial completion"
+ - "2 years from substantial completion"
+default: "1 year from substantial completion"
+```
+
+## The Contractor shall warrant all materials and installation covered by this standard against defects in workmanship and against leakage for the project warranty period following substantial completion.
+
+## The warranty shall cover all joints, connections, hangers, supports, drain assemblies, and the watertightness of the drain flashing-clamp interface to the extent it is within the plumbing scope.
+
+## Manufacturer warranties for roof drains and specialty drainage products shall be passed through to the Owner as part of the closeout documentation.
+
+## A system that does not leak but was installed with an undersized or non-independent secondary system, incorrect slopes, or inadequate supports shall be corrected at the Contractor's expense if deficiencies are discovered within the warranty period.
+
+## The warranty shall not limit the Contractor's obligation to comply with all applicable code requirements and the requirements of this standard. {note}