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SynC · Historical revision

Roof Drainage

Revision7
EditedSep 26, 2026
StatusSuperseded
Contents

View changes in this revision   Revision history

Historical revision. This is editorial revision 7, kept so citations to it stay resolvable. It is not the current text of this standard — see the current revision.

SynC Standards Team — Specifier (Platform Standards) ✓ OfficialDiscloses employment SynC (SynC Platform Team)
Remade from scratch under the authoring cheatsheet: field inventory from the decision space, a trade-off note beside every choice, ranges for the numeric ladders, and the boundary with storm drainage fixed at five feet outside the foundation wall

1 Scope

NOTE This standard governs the selection, materials, installation, and testing of the system that takes rainwater off the roof and carries it through the building to the storm sewer: the roof drains and their accessories, the secondary drainage that protects the structure when the primary drains are blocked, the leaders, and the horizontal storm piping. (1.1)
NOTE The scope begins at the roof drain body, the overflow drain body, or the scupper opening, and ends at the building storm drain five feet outside the foundation wall, where the building storm sewer begins. (1.2)
NOTE The following are outside this standard: (1.3)
  • The building storm sewer and the site storm system beyond five feet outside the foundation wall
  • The roof membrane, its base flashing, the tapered insulation and the sump formed in it, and the membrane termination at the clamping ring and at the scupper opening
  • Fabrication of through-wall scupper sleeves, conductor heads, and exterior sheet-metal downspouts
  • Eave-hung gutters and the downspouts hung from them
  • Sanitary drain, waste, and vent piping, and any combined building sewer downstream of the storm connection
  • Interior floor drains and trench drains, including the floor drains of parking structures
  • Cleanout ferrules, plugs, and access covers, which this standard locates but does not specify
  • Storm sump pumps and their basins, controls, and alarms
  • Condensation insulation of the drain bodies and the pipe
  • Firestop systems at rated penetrations, and seismic bracing of the pipe
NOTE Water that cannot leave a low-slope roof is a live load, and it grows as it deepens: a deflecting roof ponds deeper at its center, the deeper water deflects it further, and the progression has collapsed roofs whose structure was sound. A roof drainage system is therefore a structural safeguard first and a plumbing convenience second, and the secondary system is the part of it that carries the safeguard. (1.4)
1.5 Drain locations and the tributary area assigned to each drain shall be as indicated on the plumbing roof drainage plan.
1.6 Drain outlet sizes, leader sizes, and horizontal storm pipe sizes shall be as indicated on the storm riser diagram and the roof drain schedule.
1.7 Leader and horizontal pipe routing shall be as indicated on the plumbing floor plans.
NOTE Pipe sizes are a project quantity: they follow from the rainfall rate, the tributary area, the slope, and the sizing tables of the adopted plumbing code, and the same drain body serves roofs that need a 3 in. leader and roofs that need a 6 in. leader, so this standard sets what the system must be and leaves every size to the drawings. (1.8)
1.9 The Contractor shall report to the Engineer of Record any drain location, outlet size, or pipe size shown on the drawings that does not agree with the sizing calculation submitted under this standard, before the affected work is installed.

2 Referenced Standards

2.1 Materials, components, and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited.
2.2 Where the Contract Documents, the adopted plumbing code, and the referenced standards conflict, the more stringent requirement shall govern 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 1502, Roof Drainage; Section 1611, Rain Loads)
ASCE 7 Minimum Design Loads and Associated Criteria for Buildings and Other Structures (Chapter 8, Rain Loads)
ASME A112.6.4 Roof, Deck, and Balcony Drains
ASME A112.6.9 Siphonic Roof Drains
ASPE 45 Siphonic Roof Drainage Systems
ASME A112.3.1 Stainless Steel Drainage Systems for Sanitary DWV, Storm, and Vacuum Applications, Above- and Below-Ground
ASTM A74 Cast Iron Soil Pipe and Fittings
ASTM A888 Hubless Cast Iron Soil Pipe and Fittings for Sanitary and Storm Drain, Waste, and Vent Piping Applications
CISPI 301 Hubless Cast Iron Soil Pipe and Fittings for Sanitary and Storm Drain, Waste, and Vent Piping Applications
CISPI 310 Couplings for Use in Connection with Hubless Cast Iron Soil Pipe and Fittings
ASTM C1277 Shielded Couplings Joining Hubless Cast Iron Soil Pipe and Fittings
ASTM C1540 Heavy Duty Shielded Couplings Joining Hubless Cast Iron Soil Pipe and Fittings
ASTM C564 Rubber Gaskets for Cast Iron Soil Pipe and Fittings
ASTM D2665 Poly(Vinyl Chloride) (PVC) Plastic Drain, Waste, and Vent Pipe and Fittings
ASTM F891 Coextruded Poly(Vinyl Chloride) (PVC) Plastic Pipe With a Cellular Core
ASTM D2564 Solvent Cements for Poly(Vinyl Chloride) (PVC) Plastic Piping Systems
ASTM F656 Primers for Use in Solvent Cement Joints of Poly(Vinyl Chloride) (PVC) Plastic Pipe and Fittings
ASTM D2661 Acrylonitrile-Butadiene-Styrene (ABS) Schedule 40 Plastic Drain, Waste, and Vent Pipe and Fittings
ASTM D2235 Solvent Cement for Acrylonitrile-Butadiene-Styrene (ABS) Plastic Pipe and Fittings
ASTM B306 Copper Drainage Tube (DWV)
ASME B16.23 Cast Copper Alloy Solder Joint Drainage Fittings: DWV
ASME B16.29 Wrought Copper and Wrought Copper Alloy Solder-Joint Drainage Fittings: DWV
ASTM A53/A53M Pipe, Steel, Black and Hot-Dipped, Zinc-Coated, Welded and Seamless
ASME B16.12 Cast Iron Threaded Drainage Fittings
ASTM F714 Polyethylene (PE) Plastic Pipe (DR-PR) Based on Outside Diameter
ASTM F2620 Heat Fusion Joining of Polyethylene Pipe and Fittings
NSF/ANSI 14 Plastics Piping System Components and Related Materials
MSS SP-58 Pipe Hangers and Supports: Materials, Design, Manufacture, Selection, Application, and Installation
MSS SP-69 Pipe Hangers and Supports: Selection and Application
ASME A13.1 Scheme for the Identification of Piping Systems
2.3 Where the project is in a jurisdiction that has adopted the Uniform Plumbing Code, a reference in this standard to a provision of the International Plumbing Code shall be read as the corresponding provision of the Uniform Plumbing Code.

3 Submittals

3.1 Action Submittals

3.1.1 The Contractor shall submit the following for the Engineer of Record's review before any drain or pipe is procured:
  • Product data for each roof drain, overflow drain, deck drain, balcony drain, and planter drain, identifying the body material and coating, the outlet size and connection, the dome or grate material and its free inlet area, the clamping ring and gravel stop, the deck attachment, the extension, and every accessory furnished
  • Product data for each pipe and fitting material, identifying the governing product standard, the weight class, schedule, or wall construction, and the joint type
  • Product data for shielded couplings, identifying the coupling standard and the published installation torque
  • Product data for hangers, riser clamps, and inserts, with the load tables for the pipe sizes and materials furnished
  • Product data for expansion joints and flexible connectors, identifying the movement each accommodates
  • Coordination drawings showing each drain relative to the structural framing and deck openings, the sump in the tapered insulation, the leader offset below the deck, and the routing of leaders and horizontal piping through the building
  • Where siphonic drainage is selected, the siphonic system design prepared by the siphonic drain manufacturer or a designer the manufacturer qualifies, showing every drain, the pipe network with sizes and elevations, and the hydraulic calculation for the design rainfall rate
  • Where controlled-flow drainage is selected, the weir setting and the metered discharge rate of each drain at the design head
Action Submittals Requiredcheckbox
☐ Drain product data with accessories and free inlet area
☐ Pipe and fitting product data with standard, class, and joint type
☐ Shielded coupling product data with installation torque
☐ Hanger, riser clamp, and insert product data with load tables
☐ Expansion joint and flexible connector product data
☐ Coordination drawings for drains, sumps, offsets, and routing
☐ Siphonic system design
☐ Controlled-flow weir settings and metered discharge rates
3.1.2 No drain or pipe shall be installed in any area for which the action submittals covering that work have not been reviewed and returned.

3.2 Informational Submittals

3.2.1 The Contractor shall submit the following with, or before, the action submittals:
  • The roof drainage sizing calculation, stating the rainfall rate used, the tributary area of each drain including any vertical wall area that sheds onto the roof, the slope assumed for each horizontal run, and the resulting drain, leader, and horizontal pipe sizes for the primary system and, separately, for the secondary system with the primary system assumed blocked
  • Where controlled-flow drainage is selected, written confirmation from the structural engineer of record that the roof structure is designed for the ponding depth the controlled-flow design produces
  • The thermal movement calculation for each leader of plastic, copper, or steel pipe, and for each horizontal run longer than the length at which the pipe material's movement exceeds the capacity of its joints
  • The qualification records of the personnel who will make heat fusion joints where polyethylene pipe is furnished
Informational Submittals Requiredcheckbox
☐ Roof drainage sizing calculation, primary and secondary
☐ Structural confirmation of controlled-flow ponding depth
☐ Thermal movement calculation
☐ Heat fusion joining qualification records

3.3 Closeout Submittals

3.3.1 The Contractor shall submit the following before the roof drainage system is accepted:
  • Record drawings showing the installed drain locations, the leader routing, the invert elevation of every cleanout and of the building storm drain at the foundation wall, and every deviation from the Contract Documents
  • Signed test reports for every section tested, recording the test method, the head or pressure, the hold time, the result, and the witness
  • Manufacturer warranties for drains, expansion joints, and siphonic system components, assigned to the Owner
  • Maintenance instructions covering dome and grate removal and cleaning, the inspection of overflow inlets, and the cleanout locations
Closeout Submittals Requiredcheckbox
☐ Record drawings with invert elevations
☐ Signed test reports by section
☐ Assigned manufacturer warranties
☐ Maintenance instructions

4 Quality Assurance

4.1 Installer Qualifications

4.1.1 Roof drainage piping shall be installed by personnel holding the plumbing license the Authority Having Jurisdiction requires for that work.
4.1.2 Heat fusion joints in polyethylene pipe shall be made only by personnel who have completed the pipe manufacturer's training for the fusion method and the equipment used, and the training records shall be on site before fusion begins.
4.1.3 Where siphonic drainage is selected, the installing foreman shall have completed the siphonic drain manufacturer's installation training for the system furnished.

4.2 Product Marking

4.2.1 Drains shall bear the ASME A112.6.4 designation, or the ASME A112.6.9 designation where siphonic, together with the manufacturer's identification and the outlet size.
4.2.2 Pipe and fittings shall bear the manufacturer's identification, the governing product standard, and the weight class or schedule, and plastic pipe and fittings shall additionally bear the NSF/ANSI 14 mark.
4.2.3 Drains, pipe, fittings, and couplings that do not carry the required markings shall not be installed, and any that are installed shall be removed and replaced at the Contractor's expense.

4.3 Coordination With the Roofing Trade

NOTE The roof drain is the one point where the plumbing and roofing trades hold a single joint between them: the plumber sets the body and furnishes the clamping ring, the roofer dresses the membrane into the drain and sets the ring, and a drain set at the wrong elevation or a ring set before the membrane is ready leaks at a location that the piping test never reaches. (4.3.1)
4.3.2 Before the first drain is set, the Contractor shall hold a coordination meeting with the roofing contractor and the Engineer of Record to fix, for each drain type, the setting elevation of the body flange relative to the deck and the sump, the extension length required by the insulation thickness at the drain, the party responsible for setting the clamping ring, and the sequence in which the drain is set, the membrane is installed, and the ring is set.
4.3.3 The Contractor shall record the agreements reached at the coordination meeting and shall distribute the record to every party before drains are set.

4.4 Inspection Hold Points

4.4.1 The Contractor shall give the Engineer of Record and the Authority Having Jurisdiction's inspector not less than 24 hours' notice before each hold point listed below, and shall not proceed past a hold point until the inspection has been performed and released:
  • Drain bodies set and secured, before the membrane is installed over them
  • Rough piping complete and under test, before any pipe is concealed
  • Firestop and sleeve installation at rated assemblies, before the penetration is closed in
  • Overflow inlet elevations, after the roofing is complete and before the roof is accepted
4.4.2 Work concealed before its hold point has been released shall be uncovered for inspection at the Contractor's expense, and the concealing construction shall be reinstated at the Contractor's expense.

5 Drainage Design Basis

5.1 Rainfall Rate and Tributary Area

5.1.1 Primary roof drains, leaders, and horizontal storm piping shall be sized for Rainfall Rate 100 Year 1 HourRainfall Rate 100 Year 1 HourParameterEach project supplies its own value.rainfall-rate-100-year-1-hour applied to the tributary area of each drain, using the sizing method of the adopted plumbing code.
NOTE The 100-year hourly rainfall rate is a fact about the site rather than a design choice: it is read from the rainfall map of the adopted plumbing code or from the precipitation frequency data the Authority Having Jurisdiction accepts, and it ranges from about 1 in/hr in the Pacific Northwest to more than 4 in/hr along the Gulf Coast, so a system sized for the wrong region can be half the capacity the roof needs. (5.1.2)
5.1.3 The tributary area of each drain shall include the roof area that drains to it and the portion of any adjacent vertical wall that sheds rainwater onto that roof area, computed as the adopted plumbing code directs for vertical walls.
5.1.4 The rainfall rate used and the tributary area assigned to each drain shall be stated in the sizing calculation submitted under this standard.

5.2 Hydraulic Basis of the Primary System

5.2.1 The hydraulic basis of the primary drainage system shall be as indicated in the datasheet.
Primary Drainage Hydraulic Basisradio
● Gravity flow
○ Siphonic full-bore flow
NOTE A gravity system runs partly full and needs a slope on every horizontal run and a leader near every drain, and it is sized from code tables without a hydraulic model; a siphonic system primes to full-bore flow at the design rainfall, runs its horizontal collector level at high velocity, serves many drains from one leader placed where the structure allows, and needs a manufacturer's hydraulic design for every pipe and an engineered air-free inlet at every drain. (5.2.2)
NOTE Siphonic drainage repays its design cost on large, flat roofs where a gravity system would need many leaders through occupied space or a large-diameter sloped collector below the deck, and it is at its least forgiving on small roofs and on roofs with few drains, where it cannot prime reliably at light rainfall. (5.2.3)

5.3 Discharge Control of the Primary System

5.3.1 The discharge control of the primary drainage system shall be as indicated in the datasheet.
Primary Drainage Discharge Controlradio
● Free draining
○ Controlled flow with roof detention
NOTE A free-draining roof discharges as fast as the drains will pass water; a controlled-flow roof meters the discharge through a weir at each drain and stores the difference on the roof, which lets the leaders and the storm connection be smaller and is used where the site or the municipal system limits the discharge rate, at the cost of designing the roof structure for the stored water and of a roof that ponds by design after every storm. (5.3.2)

5.4 Sizing of Leaders and Horizontal Piping

5.4.1 Leaders and horizontal storm piping of a gravity system shall be sized from the sizing tables of the adopted plumbing code for the rainfall rate, the tributary area, and the slope at which each horizontal run is installed.
5.4.2 Pipe size shall not be reduced in the direction of flow.
5.4.3 The minimum slope of horizontal storm piping shall be as indicated in the datasheet.
Minimum Horizontal Storm Pipe Sloperange
in/ft
0.06250.1250.250.5
NOTE A flatter slope carries less flow in the same pipe, so the sizing tables give a larger size at 1/8 in/ft than at 1/4 in/ft for the same area; the steeper slope buys a smaller pipe and a self-cleaning velocity, and costs ceiling height on every foot of run, which is why the flatter rate is what most long horizontal runs are laid at and the steeper rate is chosen where the ceiling allows it. (5.4.4)
5.4.5 Each horizontal run shall be sized for the slope at which it is actually installed, and a run installed flatter than the slope assumed in the sizing calculation shall be resized and replaced at the Contractor's expense.

5.5 Secondary Drainage Requirement

5.5.1 A secondary drainage system shall be provided for every roof area on which water would be retained by a parapet, a curb, an adjacent wall, or any other construction above the roof surface if the primary drains at that area were blocked.
5.5.2 The secondary system shall be sized for the same rainfall rate as the primary system, over the same tributary area, on the assumption that the primary system passes no flow.
5.5.3 The capacity of the primary system shall not be credited toward the capacity of the secondary system.
NOTE The secondary system is sized as though the primary system does not exist because the condition it protects against is exactly that one: a dome buried in leaves, a leader frozen at its base, or a building drain surcharged from the sewer, any of which stops the primary system entirely and leaves the secondary inlets as the only way off the roof. (5.5.4)
5.5.5 The secondary inlet elevation and the structural rain load shall be established together, so that the depth of water on the roof at the secondary design flow, including the hydraulic head above the secondary inlet, does not exceed the depth the roof structure is designed to carry under Adopted Building CodeAdopted Building CodeParameterEach project supplies its own value.adopted-building-code and ASCE 7 Chapter 8.
NOTE The rain load on a roof is set by the water depth at the secondary inlet plus the head needed to drive the design flow through it, so raising the secondary inlet to keep it dry in ordinary storms, or choosing a small secondary opening that needs a large head, both raise the structural load in the same way. (5.5.6)

6 Roof Drains

6.1 Drain Body

6.1.1 Roof drains and overflow roof drains shall conform to ASME A112.6.4.
6.1.2 Each roof drain shall be furnished with a body, a removable dome or strainer, a clamping ring with an integral gravel stop, and the deck attachment, extension, and accessories this standard requires for the roof assembly at that drain.
6.1.3 The roof drain body material shall be as indicated in the datasheet.
Roof Drain Body Materialselect
Coated cast iron
Cast aluminum
Cast bronze
PVC or ABS plastic
NOTE Cast iron has the mass to hold the clamping ring flat under thermal cycling and the wall to survive impact from roof traffic and ballast; aluminum weighs a third as much, which matters on a lightweight deck or a re-roof, and resists the concentrated runoff on most roofs, though it pits under some chemical exhausts; bronze suits copper leaders and corrosive marine air at a price several times that of iron; plastic bodies are the lightest and are joined directly to plastic leaders by solvent cement, and they are limited to the sizes and the temperatures their listing covers and to roofs where the deck attachment does not depend on the body's stiffness. (6.1.4)
6.1.5 The coating on cast iron drain bodies shall be as indicated in the datasheet.
Cast Iron Drain Body Coatingradio
○ Bituminous or enamel dip coating
○ Epoxy or polyester powder coating
Manufacturer's standard (by default)
NOTE The dip coating is what every cast iron drain leaves the foundry with and is adequate wherever the runoff is ordinary rainwater; a powder coating is specified where the roof receives salt spray, cooling tower drift, or the exhaust of a process, because the concentrated runoff that reaches the drain bowl attacks the iron where the dip coating is thinnest. (6.1.6)
6.1.7 Drain bodies over which a powder coating is specified shall be coated on every wetted surface, including the underside of the flange and the interior of the outlet.

6.2 Outlet Connection

6.2.1 The roof drain outlet connection shall be as indicated in the datasheet.
Roof Drain Outlet Connectionselect
No-hub outlet for a shielded coupling
Inside caulk outlet for a hub-and-spigot joint
Threaded outlet
Push-on gasketed outlet
Solvent cement socket outlet
NOTE The outlet has to match the leader: a no-hub outlet takes the shielded coupling used on hubless cast iron and lets the leader be connected and disconnected without disturbing the clamped membrane above; an inside caulk outlet receives a spigot end and is joined with a compression gasket or caulked lead; a threaded outlet suits steel or a threaded adapter and is the one that cannot be made up after the drain is fixed to the deck without turning the pipe; a push-on outlet joins a plain-end pipe with a gasket; and a solvent cement socket is the outlet of a plastic drain body. (6.2.2)
6.2.3 The outlet connection shall be of the type and size that the leader material and joining method selected in this standard can be joined to without a field-fabricated adapter.
6.2.4 The outlet orientation of each drain, whether bottom, side, or offset, shall be as indicated on the roof drain schedule.

6.3 Dome Strainer

6.3.1 The dome strainer material shall be as indicated in the datasheet.
Roof Drain Dome Strainer Materialselect
Cast iron
Cast aluminum
Polyethylene or polypropylene
Cast bronze
NOTE The dome is the part of the drain that roof traffic, ballast, and ultraviolet exposure reach: a cast iron dome survives being stepped on and is the heaviest to lift for cleaning; an aluminum dome is light and does not rust but dents; a polymer dome costs the least, cannot corrode, and turns brittle after years of sun and can crack under a boot in cold weather; a bronze dome matches a bronze body and outlasts all of them at a price that is justified only where the body is bronze. (6.3.2)
6.3.3 Each roof drain on a low-slope roof shall have a dome strainer extending not less than 4 in. above the roof surface at the drain, with a free inlet area not less than 1.5 times the cross-sectional area of the drain outlet.
NOTE The 4 in. height keeps the inlet above the layer of leaves and gravel that collects at a roof low point, and the free area ratio means that half the dome can be blocked before the strainer, rather than the leader, sets the drain's capacity. (6.3.4)
6.3.5 Domes shall be secured to the drain body so that they cannot be dislodged by wind, foot traffic, or ballast, and shall be removable for cleaning without cutting or breaking any part of the drain.
6.3.6 Roof drains on ballasted or gravel-surfaced roofs shall have a gravel stop integral with the clamping ring, extending above the ballast surface, with slots or perforations no larger than will retain the ballast.

6.4 Deck Attachment

6.4.1 The attachment of the roof drain to the deck shall be as indicated in the datasheet.
Roof Drain Deck Attachmentselect
Underdeck clamp
Underdeck clamp with a sump receiver spanning the deck opening
Cast into the concrete deck
NOTE The deck attachment carries the weight of the drain, the water in it, and any load the leader connection transfers, and keeps that load off the membrane: an underdeck clamp alone bears on a solid deck of wood or concrete; a sump receiver is a steel pan that spans the flutes of a metal deck and gives the underdeck clamp a flat surface to bear on, and it also forms the recess the drain sits in; a drain cast into a concrete deck is set on the form before the pour and needs no clamp, and it cannot be moved afterward. (6.4.2)
6.4.3 The drain shall not be supported by the leader, and the leader shall not be supported by the drain.
6.4.4 Where an underdeck clamp is furnished, it shall bear on the deck around the full opening and shall be tightened after the body is set to the coordinated elevation.
6.4.5 Where a drain is cast into a concrete deck, the Contractor shall secure the body against movement during the pour and shall verify its elevation before and after the pour.

6.5 Extension for Insulation Thickness

6.5.1 The roof drain extension shall be as indicated in the datasheet.
Roof Drain Extensionselect
None because the body flange reaches the membrane plane
Fixed extension of the length the insulation thickness requires
Adjustable extension
Derived — the insulation thickness at the drain sump and the extension lengths the drain manufacturer publishes for that body (by default)
NOTE The body is anchored at the deck and the clamping ring has to sit at the membrane, so the distance between them is the insulation thickness at the drain, and the extension is whatever the manufacturer makes to bridge it; an adjustable extension takes up field variation in that thickness and costs more than a fixed one of the right length. (6.5.2)
6.5.3 Extensions shall be of the same manufacturer and series as the drain body, and shall be sealed to the body by the method the manufacturer publishes.

6.6 Accessories

6.6.1 The roof drain accessories furnished shall be as indicated in the datasheet.
Roof Drain Accessoriescheckbox
☐ Secured vandal-resistant dome
☐ Sediment bucket below the dome
☐ Electric dome heater for de-icing
☐ Deck plate for a wood deck
☐ Underdeck insulation shield
NOTE A vandal-resistant dome is bolted through the clamping ring and needs a tool to remove, which stops it walking off an accessible roof and slows every cleaning; a sediment bucket catches grit before the leader and needs emptying; a dome heater keeps the inlet open where snowmelt refreezes at the drain in a freezing climate; and an insulation shield lets the underside insulation be applied without a gap at the body. (6.6.2)
6.6.3 Where an electric dome heater is furnished, it shall be listed for the purpose, self-regulating, and connected through a ground-fault protection device.

6.7 Membrane Clamp Interface

6.7.1 The clamping ring and its bolts shall be furnished with the drain, of the drain manufacturer's design for that body, and shall be delivered to the roofing contractor with the drain set.
6.7.2 The clamping ring shall not be set until the roofing contractor has dressed the membrane into the drain and confirmed that the membrane is ready to be clamped.
NOTE The membrane termination at the drain, the bonding of the membrane to the flange, the sump formed in the tapered insulation, and the setting and tightening of the clamping ring are specified in Membrane RoofingMembrane RoofingResolves to the current adopted revision.sync/membrane-roofing; this standard furnishes the ring and sets the body it clamps to. (6.7.3)
6.7.4 The Contractor shall set each drain body so that the top of the flange, or of the extension where one is furnished, lies at the membrane plane agreed at the coordination meeting, and so that the membrane can be clamped to it without a step or a wrinkle.

7 Deck, Balcony, and Planter Drains

7.1 Deck and Balcony Drains

7.1.1 Drains in walkable decks, balconies, and terraces that discharge to the building storm system shall conform to ASME A112.6.4 and shall have a flat, secured grate in place of a dome.
7.1.2 Flat grates on walking surfaces shall have a free inlet area not less than two times the cross-sectional area of the drain outlet.
NOTE A flat grate sits in the traffic and the debris rather than above it, so it needs the larger free area to hold its capacity when partly covered. (7.1.3)
7.1.4 Grate openings on walking surfaces shall be sized and oriented so that they do not admit a heel or a cane tip, and grates on accessible routes shall comply with the adopted accessibility standard for opening width and orientation.
7.1.5 The grate material for deck and balcony drains shall be as indicated in the datasheet.
Deck and Balcony Drain Grate Materialselect
Coated cast iron
Nickel bronze
Stainless steel
Polished bronze
NOTE Cast iron is the working grate for a service deck or a parking level over storm piping; nickel bronze is the finish-grade grate for a terrace or a balcony where the grate is seen and walked on barefoot, and it holds its color without polishing; stainless steel is chosen where the deck is washed with chlorides or where the design calls for it; polished bronze is a decorative finish that tarnishes and is maintained by the Owner. (7.1.6)
7.1.7 Drains in decks with a topping slab, pavers, or a wearing surface over the waterproofing shall be furnished with an extension or a secondary clamping collar so that the waterproofing is clamped at its own plane and the grate finishes flush at the wearing surface.
7.1.8 Deck and balcony drains over occupied space shall be furnished with an underdeck clamp or shall be cast into the deck, on the same basis as roof drains.

7.2 Planter Drains

7.2.1 Drains in roof planters and raised planting beds that discharge to the building storm system shall conform to ASME A112.6.4 and shall have a dome strainer with an extension reaching above the top of the drainage layer.
7.2.2 Planter drains shall be wrapped with a filter fabric over the dome, or furnished with a perforated extension that admits water from the drainage layer while excluding growing medium.
NOTE A planter drain that draws growing medium into the leader plugs the leader at the first offset below it, where no cleanout reaches. (7.2.3)

8 Secondary Drainage

8.1 Secondary Drainage Provisions

8.1.1 The provisions by which secondary drainage is furnished on the project shall be as indicated in the datasheet.
Secondary Drainage Provisions Furnishedcheckbox
☐ Overflow roof drains with independent piping
☐ Overflow scuppers through the parapet or perimeter wall
☐ Free-draining roof edge with no construction above the roof surface
8.1.2 The secondary provision serving each roof area shall be as indicated on the plumbing roof drainage plan.
NOTE An overflow scupper is an opening in a wall with nothing to freeze, block, or pipe, and it works wherever the roof low point lies against a parapet or a perimeter wall; an overflow drain with its own piping is the provision for a low point remote from any wall, for a parapet too tall to cut, or for a facade that will not accept an opening, at the cost of a second piping system through the building; and a roof whose edge is open to the sky needs neither, because water cannot be retained on it. (8.1.3)
8.1.4 Where the drawings show a roof area with construction above the roof surface and no secondary provision, the Contractor shall report the condition to the Engineer of Record before the roof drains at that area are set.

8.2 Overflow Roof Drains

8.2.1 Requirements in this article apply where overflow roof drains are furnished.
8.2.2 Overflow roof drains shall conform to ASME A112.6.4 and shall be of the same body material, coating, dome material, deck attachment, and extension as the primary roof drains they back up.
8.2.3 Each overflow roof drain shall have a water dam at its inlet, integral with the drain or furnished by the drain manufacturer for that body, setting the inlet flow line above the adjacent roof low point by the height indicated in the datasheet.
Overflow Drain Inlet Height Above the Roof Low Pointrange
in
22.5346
NOTE The dam keeps the overflow drain dry until water on the roof stands deeper than the primary drain would ever allow, which is the signal that the primary drain has failed; the adopted codes set the 2 in. minimum, and a taller dam keeps the overflow inactive through heavier ordinary storms at the price of a deeper pond and a heavier rain load before it ever operates. (8.2.4)
8.2.5 The inlet flow line of each overflow drain shall be measured from the low point of the finished roof surface adjacent to the drain, not from the deck.
8.2.6 Overflow drain piping shall be entirely separate from the primary drain piping from the drain body to the point of discharge, and the two systems shall not be joined at any point.
8.2.7 Overflow drain piping shall discharge above grade at a location that building occupants or maintenance personnel will normally see, so that flow from it is a visible signal of a blocked primary system.
8.2.8 The overflow discharge arrangement shall be as indicated in the datasheet.
Overflow Drain Discharge Arrangementselect
Through-wall outlet nozzle discharging above grade
Downspout to a splash block at grade
Separate connection to the site storm system where the Authority Having Jurisdiction permits it
8.2.9 The location of each overflow discharge shall be as indicated on the plumbing floor plans and the building elevations.
NOTE A wall nozzle puts the discharge on the facade where it is seen from the ground and needs nothing below it but a surface that can take the splash; a downspout to a splash block moves the discharge to grade at the cost of a pipe on the wall and a discharge that can be mistaken for the primary one; a separate connection to the site storm system is permitted by some jurisdictions and removes the visible signal entirely, so where it is used the jurisdiction's own requirement for an indication of overflow governs. (8.2.10)
8.2.11 Overflow discharge shall not be directed onto a walkway, an entrance, a lower roof without its own drainage, or the top of a wall.

8.3 Overflow Scuppers

8.3.1 Requirements in this article apply where overflow scuppers are furnished.
8.3.2 Each overflow scupper shall be an opening through the parapet or perimeter wall at the roof low point it serves, with its flow line above the adjacent roof low point by the height indicated in the datasheet.
Overflow Scupper Flow Line Height Above the Roof Low Pointrange
in
22.5346
NOTE The scupper flow line follows the same reasoning as the overflow drain dam: high enough to stay dry while the primary drains work, and no higher than the structure can afford, since every inch of flow line height is an inch of water on the whole roof area before the scupper takes any of it. (8.3.3)
8.3.4 The clear opening height of each overflow scupper shall be not less than the height indicated in the datasheet.
Overflow Scupper Minimum Clear Opening Heightrange
in
4681012
NOTE The adopted codes set the 4 in. floor on opening height so that a scupper cannot be blinded by a single leaf or a sheet of ice; a taller opening passes the design flow at less head, which lowers the rain load, and it also makes a larger hole in the wall for the sheet metal and the membrane to close. (8.3.5)
8.3.6 The width of each overflow scupper shall be established by the Engineer of Record from the design flow and the head available below the permitted ponding depth, and shall be not less than the width the adopted plumbing code requires for the tributary area.
8.3.7 The width of each overflow scupper shall be as indicated on the plumbing roof drainage plan.
8.3.8 The Contractor shall verify the flow line elevation of each scupper opening against the finished roof low point after the roofing is complete and before the scupper sleeve is fabricated, and shall report any opening whose flow line falls outside the height indicated in the datasheet.
NOTE The through-wall sleeve, the conductor head, and any downspout below the scupper are fabricated under Sheet Metal Flashing And TrimSheet Metal Flashing and TrimResolves to the current adopted revision.sync/sheet-metal-flashing-and-trim, and the membrane flashing into the opening is installed under Membrane RoofingMembrane RoofingResolves to the current adopted revision.sync/membrane-roofing; this standard sets the opening's location, flow line, and size. (8.3.9)

9 Controlled-Flow Drainage

9.1 Requirements in this section apply where controlled flow with roof detention is selected as the discharge control of the primary system.
9.2 Where controlled flow is selected, each primary roof drain shall be a controlled-flow roof drain conforming to ASME A112.6.4, with a weir or flow-restricting device of the drain manufacturer's design that limits the discharge to the metered rate at the design head.
9.3 Where controlled flow is selected, the metered discharge rate and the design head at each drain shall be as indicated on the roof drain schedule.
9.4 Where controlled flow is selected, the weir setting of each drain shall be fixed at the factory or field-set and locked to the scheduled rate, and shall be recorded on the record drawings.
9.5 Where controlled flow is selected, the secondary drainage system shall be sized for the full design rainfall rate with the controlled-flow drains assumed blocked, and its inlets shall be set no higher than the maximum ponding depth the roof structure is designed for.
9.6 Where controlled flow is selected, the Contractor shall not install the drains until the structural engineer of record's written confirmation of the design ponding depth has been submitted under this standard.
NOTE A controlled-flow roof is a detention basin whose walls are the parapets and whose floor is the roof structure, and the drain weirs are the outlet control: the roof stores several inches of water after a storm and releases it over hours, so the structure must be designed for that stored depth plus the secondary head, and the membrane must tolerate standing water as a matter of routine rather than as a defect. (9.7)

10 Siphonic Drainage

10.1 Requirements in this section apply where siphonic full-bore flow is selected as the hydraulic basis of the primary system.
10.2 Where siphonic drainage is selected, roof drains shall conform to ASME A112.6.9 and shall be furnished with the air baffle and the inlet geometry the drain manufacturer designed for full-bore priming.
10.3 Where siphonic drainage is selected, the system shall be designed in accordance with ASPE 45 by the siphonic drain manufacturer or by a designer the manufacturer qualifies, for the design rainfall rate stated in this standard, and the design shall be submitted under this standard before any pipe is ordered.
10.4 Where siphonic drainage is selected, the pipe sizes, the elevations, the fitting types, and the routing of the siphonic network shall be installed exactly as the siphonic design shows, and no size, elevation, or fitting shall be changed in the field without the siphonic designer's written revision.
NOTE A siphonic network is a hydraulic circuit in balance: each pipe is sized so that the drains it serves prime together and the pressures at every junction stay within the design range, and a field substitution of one size or one fitting type unbalances the circuit so that some drains never prime and others cavitate. (10.5)
10.6 Where siphonic drainage is selected, the horizontal collector may be installed level and shall be installed at the elevations the siphonic design shows.
10.7 Where siphonic drainage is selected, the piping shall be of a material the siphonic designer qualifies for the negative pressures the design produces, and polyethylene pipe used for it shall conform to ASTM F714 and shall be joined by heat fusion in accordance with ASTM F2620.
10.8 Where siphonic drainage is selected, the network shall be anchored and guided as the siphonic design shows, so that the thrust and the thermal movement of a full-bore, high-velocity pipe are taken to the structure and not to the drains.
10.9 Where siphonic drainage is selected, the transition from the siphonic network to the gravity building storm drain shall be made at the location and by the vented fitting the siphonic design shows, and the gravity piping downstream of the transition shall be sized and sloped as a gravity system under this standard.
10.10 Where siphonic drainage is selected, the secondary drainage system shall be provided under this standard and may itself be siphonic, sized for the full design rainfall rate with the primary network assumed blocked.

11 Storm Piping Materials

11.1 Material Selection by Location

11.1.1 The material of leaders and horizontal storm piping above the floor slab shall be as indicated in the datasheet.
Above-Ground Storm Piping Materialselect
Hubless cast iron
Hub-and-spigot cast iron
PVC drain, waste, and vent pipe
ABS drain, waste, and vent pipe
Copper drainage tube
Galvanized steel pipe with drainage fittings
Stainless steel drainage pipe
Polyethylene pipe, heat fused
11.1.2 The material of storm piping below the floor slab and within the building footprint shall be as indicated in the datasheet.
Below-Slab Storm Piping Materialselect
Hub-and-spigot cast iron
Hubless cast iron with heavy-duty couplings
PVC drain, waste, and vent pipe
ABS drain, waste, and vent pipe
Stainless steel drainage pipe
Polyethylene pipe, heat fused
NOTE Storm piping carries a slug of cold water at high velocity in every storm and sits empty between them, and the material decision is mostly about what that does to the building: cast iron damps the noise of the rush and does not move with temperature, which is why it is the common choice in a leader chase beside occupied rooms; plastic pipe costs and weighs less, is joined without a torque wrench, transmits the sound of the flow through a partition, and moves enough with temperature that every long run needs an expansion provision; copper is chosen where the leader is exposed as an architectural element; galvanized steel with drainage-pattern fittings is a permitted material that survives where the leader is exposed to impact; stainless steel is specified for the corrosive runoff of a process roof; and heat-fused polyethylene is the material of siphonic networks and is a permitted gravity material in the jurisdictions whose code lists it. (11.1.3)
NOTE Below a slab the pipe is reached only by breaking the floor, so the choice there weighs a joint that stays tight under settlement and a wall that survives the backfill: a hub-and-spigot gasketed joint tolerates deflection, a hubless joint needs the heavy-duty coupling to hold its alignment without the pipe being supported at every coupling, and plastic pipe needs an embedment that supports it continuously. (11.1.4)
11.1.5 Plastic storm piping shall not be installed within a return-air plenum unless it is listed for that use, and where it is not listed the piping within the plenum shall be of a material this standard permits that is not plastic.
11.1.6 Transitions between piping materials shall be made with a fitting or coupling listed for the two materials joined, and a transition shall not be made with a coupling intended for one material alone.

11.2 Hubless Cast Iron

11.2.1 Requirements in this article apply where hubless cast iron is selected for a location.
11.2.2 Hubless cast iron pipe and fittings shall conform to ASTM A888 or CISPI 301.
11.2.3 The weight class of hubless cast iron pipe shall be as indicated in the datasheet.
Hubless Cast Iron Weight Classradio
● Service weight
○ Extra-heavy weight
NOTE Extra-heavy pipe carries a thicker wall for the same nominal size and is specified where the pipe is buried under a slab that sees vehicle loads or where the leader is exposed to impact. (11.2.4)
11.2.5 The shielded coupling type for hubless cast iron shall be as indicated in the datasheet.
Hubless Coupling Typeradio
● Standard shielded coupling to CISPI 310 and ASTM C1277
○ Heavy-duty shielded coupling to ASTM C1540
NOTE A standard coupling holds the joint watertight and relies on the hangers at each side of it to hold the pipe in line; a heavy-duty coupling adds a wider, thicker shield and more clamp bands, so that the joint itself resists deflection and the internal pressure of a surcharged or tested line. (11.2.6)
11.2.7 Hubless joints below the slab, and hubless joints in any leader that is tested above the code minimum head, shall be made with heavy-duty shielded couplings.
11.2.8 Shielded couplings shall have a stainless steel shield, stainless steel clamp bands, and an elastomeric sleeve gasket conforming to ASTM C564, and shall be tightened with a calibrated torque wrench to the coupling manufacturer's published torque.
NOTE Couplings tightened by feel are the recurring source of leaks at test on hubless systems: an under-torqued band leaks at the test head and an over-torqued band strips or cuts the gasket, and neither is visible until water is in the line. (11.2.9)

11.3 Hub-and-Spigot Cast Iron

11.3.1 Requirements in this article apply where hub-and-spigot cast iron is selected for a location.
11.3.2 Hub-and-spigot cast iron pipe and fittings shall conform to ASTM A74.
11.3.3 The hub-and-spigot joint type shall be as indicated in the datasheet.
Hub-and-Spigot Joint Typeradio
● Compression gasket to ASTM C564
○ Caulked lead and oakum
NOTE A compression gasket joint is made by driving the spigot into a gasket seated in the hub, and it flexes without leaking; a caulked joint is made by packing oakum and pouring lead, and it is the joint some jurisdictions require to match an existing system and the joint chosen where the seal cannot depend on an elastomer. (11.3.4)
11.3.5 Compression gaskets shall be lubricated with the gasket manufacturer's lubricant and the spigot shall be driven fully home in the hub.
11.3.6 Where caulked joints are furnished, the lead shall be poured in one pour to fill the hub and caulked to a dense, flush finish.

11.4 PVC and ABS Pipe

11.4.1 Requirements in this article apply where PVC or ABS drain, waste, and vent pipe is selected for a location.
11.4.2 PVC pipe and fittings shall conform to ASTM D2665, and the PVC wall construction shall be as indicated in the datasheet.
PVC Storm Pipe Wall Constructionradio
● Solid wall Schedule 40 to ASTM D2665
○ Cellular core to ASTM F891
NOTE Cellular-core pipe has a foamed inner layer between two solid skins, weighs less and costs less than solid wall, and carries a lower crush rating and a lower impact resistance, which is why it is permitted above ground in the adopted codes and restricted below a slab in many jurisdictions. (11.4.3)
11.4.4 ABS pipe and fittings shall conform to ASTM D2661.
11.4.5 PVC joints shall be made with a primer conforming to ASTM F656 and a solvent cement conforming to ASTM D2564, and ABS joints shall be made with a solvent cement conforming to ASTM D2235.
11.4.6 PVC and ABS shall not be joined to each other by solvent cement, and a transition between them shall be made with a listed transition cement or a listed mechanical coupling.
11.4.7 Solvent cement joints shall be made at ambient temperatures within the range the cement manufacturer publishes, and joints shall be allowed to cure for the period the cement manufacturer publishes for the pipe size and the temperature before the line is filled or tested.
11.4.8 Plastic pipe shall be cut square, deburred, and dry-fit to full socket depth before cement is applied, and pipe that does not enter the socket to full depth shall not be forced.

11.5 Copper Drainage Tube

11.5.1 Requirements in this article apply where copper drainage tube is selected for a location.
11.5.2 Copper drainage tube shall conform to ASTM B306, and fittings shall be cast copper alloy drainage fittings conforming to ASME B16.23 or wrought copper drainage fittings conforming to ASME B16.29.
11.5.3 Copper joints shall be soldered with a lead-free solder, and the joint shall be cleaned of flux residue after soldering.
11.5.4 Copper tube shall be isolated from ferrous hangers and from contact with any dissimilar metal by a dielectric insert or a plastic-coated hanger.

11.6 Galvanized Steel Pipe

11.6.1 Requirements in this article apply where galvanized steel pipe is selected for a location.
11.6.2 Galvanized steel pipe shall conform to ASTM A53/A53M, Schedule 40, hot-dip galvanized, and fittings shall be galvanized cast iron threaded drainage fittings conforming to ASME B16.12.
NOTE Drainage-pattern fittings carry a recessed shoulder so that the pipe end does not project into the flow path, and a pressure-pattern fitting used in its place leaves a ledge that catches debris at every joint. (11.6.3)
11.6.4 Threaded joints shall be made with a thread compound that is compatible with the zinc coating, and the cut end of each pipe shall be reamed to full bore before assembly.

11.7 Stainless Steel Drainage Pipe

11.7.1 Requirements in this article apply where stainless steel drainage pipe is selected for a location.
11.7.2 Stainless steel drainage pipe and fittings shall conform to ASME A112.3.1 and shall be joined by the push-fit gasketed joint or the mechanical coupling that standard covers.
11.7.3 Stainless steel shall not be brought into contact with carbon steel tools, brushes, or wool, and tools used on stainless steel shall be dedicated to it.

12 Leaders and Horizontal Piping

12.1 Separation From Sanitary Drainage

12.1.1 Storm piping within the building shall be separate from sanitary drain, waste, and vent piping, and a leader or storm drain shall not receive sanitary waste.
12.1.2 Sanitary piping shall not be used as a leader or a storm drain, and a leader shall not serve as a vent.
12.1.3 Where the adopted code and the Authority Having Jurisdiction permit the building storm drain to connect to a combined sewer, each leader or the building storm drain shall be trapped by a running trap with a cleanout on each side, as the adopted plumbing code directs for combined connections.
NOTE Without the trap, sewer gas from a combined sewer rises through every leader to the roof drains, and a dry leader in a drought carries it into the building at the first open cleanout. (12.1.4)

12.2 Leader Base and Offsets

12.2.1 The base of each leader shall turn to the horizontal through a long-sweep fitting or two 45-degree fittings, and a short-radius quarter bend shall not be used at the base of a leader.
12.2.2 Offsets in a leader below the roof drain, made to move the leader out of the drain sump and into a chase, shall be made with fittings no sharper than 45 degrees, and the offset shall be supported so that the drain carries none of its weight.
NOTE The bottom of a leader is where the falling column of water turns and where every piece of debris that got past the dome stops: a sweeping turn keeps the velocity and carries the debris on, and a sharp turn takes the impact of the column at every storm and traps what it carried. (12.2.3)

12.3 Cleanout Locations

12.3.1 Cleanouts shall be provided at the base of each leader, at each change in direction of horizontal piping greater than 45 degrees, at intervals not exceeding 100 ft along horizontal runs, and where the building storm drain leaves the building.
12.3.2 Cleanouts shall be installed so that they can be opened and rodded without removing permanent construction, and cleanouts in finished spaces shall be provided with an access cover at the finished surface.
NOTE Cleanout ferrules, plugs, and access covers are specified in Plumbing SpecialtiesPlumbing SpecialtiesResolves to the current adopted revision.sync/plumbing-specialties; this standard sets where cleanouts occur on the storm piping. (12.3.3)

12.4 Building Storm Drain and Sewer Connection

12.4.1 The building storm drain shall extend to a point five feet outside the foundation wall at the location and invert elevation indicated on the plumbing site plan.
12.4.2 The Contractor shall verify the invert elevation of the building storm sewer at the connection point before the horizontal storm piping inside the building is installed, and shall report any elevation that does not permit the minimum slope indicated in the datasheet.
NOTE An invert discovered too high after the horizontal piping is hung leaves no fix short of resetting every hanger on the run, so the elevation is checked at the outside end first. (12.4.3)
12.4.4 The building storm drain shall pass through the foundation wall in a sleeve or a wall pipe with clearance for the pipe to move, and the annular space shall be sealed against water entry.
12.4.5 Where the horizontal storm piping cannot reach the building storm drain by gravity, it shall discharge to a storm sump at the location indicated on the plumbing floor plans.
NOTE The storm sump, its pump, and its controls are furnished under Sump And Sewage PumpsSump and Sewage PumpsResolves to the current adopted revision.sync/sump-and-sewage-pumps; this standard carries the piping to the sump inlet. (12.4.6)
12.4.7 Storm water that has entered the building storm drain shall not be discharged into the sanitary system, and sanitary waste shall not be discharged into a storm sump.

13 Expansion and Movement

13.1 Expansion Provision at the Roof Drain

13.1.1 The expansion provision between the roof drain outlet and the leader shall be as indicated in the datasheet.
Roof Drain Outlet Expansion Provisionselect
None
Expansion joint below the drain outlet
Flexible elastomeric connector below the drain outlet
NOTE A cast iron leader on a rigid deck needs no provision at the drain; an expansion joint below the outlet takes up the vertical movement of a plastic or copper leader and the deflection of a long-span deck under snow, so that the drain flange is not levered off the membrane; a flexible connector does the same for a smaller movement and also isolates the drain from the leader's vibration. (13.1.2)
13.1.3 Where an expansion joint or flexible connector is furnished below a drain, it shall be rated for the movement stated in the thermal movement calculation and for the test pressure of the leader, and the leader shall be anchored below it so that the movement is taken at the joint.

13.2 Leader and Horizontal Movement

13.2.1 Where the thermal movement calculation shows a movement in a leader or a horizontal run greater than the movement the pipe's joints accommodate, an expansion joint, an expansion loop, or an offset with swing joints shall be provided for that run.
NOTE Plastic and copper pipe move several times as much as cast iron for the same temperature change, and a leader that runs from a sunlit roof to a cool basement sees the largest change in the building; the movement accumulates over the leader's height and arrives at the base fitting, where a solvent-cemented plastic joint has no give at all. (13.2.2)
13.2.3 Expansion joints in storm piping shall be of a type listed for drainage service, installed with the pipe anchored on one side and guided on the other, and located where they remain accessible.
13.2.4 Plastic leaders shall be anchored at the top or at one intermediate floor and guided at the others so that the movement is directed toward the expansion provision.
13.2.5 Storm piping crossing a building expansion joint or a seismic joint shall be provided with a flexible connection accommodating the movement in every direction stated on the structural drawings.

14 Hangers and Supports

14.1 Hanger Materials

14.1.1 Hangers and supports shall conform to MSS SP-58 and shall be selected and applied in accordance with MSS SP-69.
14.1.2 The hanger and support material shall be as indicated in the datasheet.
Hanger and Support Materialselect
Carbon steel, electroplated zinc
Carbon steel, hot-dip galvanized
Stainless steel
Copper-plated or plastic-coated carbon steel
NOTE An electroplated hanger is the ordinary interior hanger and is adequate wherever the pipe stays dry on the outside; hot-dip galvanizing is chosen for a parking level, a loading dock, or any location that is washed or wet; stainless steel is specified where the atmosphere is corrosive; and a copper-plated or plastic-coated hanger is what isolates copper tube from a ferrous hanger. (14.1.3)
14.1.4 Hangers on piping in a parking structure, a loading dock, an unconditioned space open to the weather, or any washed-down space shall be hot-dip galvanized or stainless steel.
14.1.5 Hangers on insulated storm piping shall bear on an insulation shield and insert at each support, so that the vapor retarder is continuous across the hanger.
14.1.6 Field-fabricated hangers, perforated strap, wire, and chain shall not be used to support storm piping.

14.2 Horizontal Support Spacing

14.2.1 Horizontal cast iron storm piping shall be supported at each side of every coupling or hub and at intervals not exceeding 5 ft, and 10 ft lengths of pipe may be supported at 10 ft intervals with a support at each coupling.
14.2.2 Horizontal PVC and ABS storm piping shall be supported at intervals not exceeding 4 ft, and the hanger shall hold the pipe without constricting it so that the pipe can move through it.
14.2.3 Horizontal copper drainage tube shall be supported at intervals not exceeding 6 ft for tube 1-1/4 in. and smaller and 10 ft for tube 1-1/2 in. and larger.
14.2.4 Horizontal galvanized steel and stainless steel storm piping shall be supported at intervals not exceeding 12 ft.
14.2.5 Horizontal polyethylene storm piping shall be supported at the intervals the pipe manufacturer publishes for the pipe size and the temperature, and in a siphonic network at the intervals the siphonic design shows.
14.2.6 Where the adopted plumbing code requires closer support than this standard states for a material, the code spacing shall govern.
NOTE A support at each side of a cast iron coupling keeps the joint from carrying a bending moment: the coupling is a watertight seal and not a structural connection, and a span load across it works the gasket loose with every fill and drain of the line. (14.2.7)
14.2.8 Horizontal piping shall be supported so that it holds the installed slope without sag between supports, and the slope shall be verified with a level at each support before the piping is concealed.

14.3 Vertical Support

14.3.1 Each leader shall be supported at its base and at every floor by a riser clamp bearing on the structure, and the clamp shall carry the leader's weight to the structure rather than to the drain above or to the horizontal piping below.
14.3.2 Cast iron leaders shall be supported at intervals not exceeding 15 ft, and plastic and copper leaders at every floor and at intervals not exceeding 10 ft.
14.3.3 Riser clamps on plastic leaders shall be installed so that the leader can move through the clamp at every floor except the anchor floor.
14.3.4 Leaders shall be installed plumb, and an offset shall be supported on each side of the offset.

14.4 Seismic Restraint

14.4.1 The seismic restraint of storm piping shall follow from Seismic Design CategorySeismic Design CategoryParameterEach project supplies its own value.seismic-design-category and the pipe size threshold at which the adopted building code and ASCE 7 Chapter 13 require restraint of a nonstructural piping system.
14.4.2 Where seismic restraint is required, the storm piping shall be braced laterally and longitudinally in accordance with Vibration Isolation And Seismic RestraintVibration Isolation and Seismic RestraintResolves to the current adopted revision.sync/vibration-isolation-and-seismic-restraint, and the bracing shall not restrain the movement that the expansion provisions in this standard depend on.

15 Insulation and Penetrations

15.1 Condensation Insulation

15.1.1 Roof drain bodies, overflow drain bodies, horizontal storm and overflow piping inside the building, and the leaders in the locations that standard identifies shall be insulated for condensation control in accordance with Plumbing InsulationPlumbing InsulationResolves to the current adopted revision.sync/plumbing-insulation.
15.1.2 Drain bodies shall be set, and the leader offsets below them made, so that the insulation and its vapor retarder can be applied continuously over the body and the piping without a gap at the underdeck clamp or the outlet.
NOTE Cold rainwater fills the drain body and the horizontal piping to well below the dew point of a conditioned building, and an uninsulated drain body over a finished ceiling sweats onto it during every storm and for hours afterward; the insulation is specified elsewhere, but the drain has to be set so that it can be applied. (15.1.3)

15.2 Sleeves and Firestopping

15.2.1 Storm piping passing through a floor, a wall, or a roof deck shall pass through a sleeve or a cored opening sized to leave clearance around the pipe, and the annular space shall be sealed against the passage of water at floors.
15.2.2 Storm piping passing through a fire-resistance-rated floor, wall, or shaft shall be firestopped with a system listed for the pipe material, the pipe size, and the assembly, installed in accordance with FirestoppingFirestoppingResolves to the current adopted revision.sync/firestopping.
NOTE A plastic leader through a rated floor is the case that needs the intumescent collar rather than a sealant, because the pipe itself burns away and leaves the opening it occupied. (15.2.3)
15.2.4 The roof deck opening at each drain shall be located, sized, and reinforced as the structural drawings show, and the Contractor shall not cut an opening in the deck that the structural drawings do not show without the structural engineer of record's written direction.

16 Identification

16.1 Storm piping in mechanical rooms, in accessible ceiling spaces, in chases with access, and wherever it is exposed shall be identified with pipe markers conforming to ASME A13.1.
16.2 The pipe marker legend shall be as indicated in the datasheet.
Storm Pipe Marker Legendselect
STORM
STORM DRAIN
RAINWATER
ROOF DRAIN
NOTE The legend is the word maintenance staff will read when they open a ceiling and find two black pipes, so it is chosen to match the word used on the Owner's other buildings and on the record drawings, and none of the four is wrong. (16.3)
16.4 Markers shall be placed at intervals not exceeding 25 ft on straight runs, at each change of direction, at each side of a wall or floor penetration, at each cleanout, and at each point where the piping enters or leaves a concealed space.
16.5 Overflow drain piping shall be marked with a legend that distinguishes it from primary storm piping, and the legend shall include the word OVERFLOW.

17 Testing

17.1 Test Method

17.1.1 Storm piping shall be tested after rough-in and before any pipe is concealed by construction, insulation, or backfill, by the method indicated in the datasheet.
Storm Piping Test Methodradio
● Water test
○ Air test
NOTE A water test shows a leak as a wet spot at the joint, and a water column holds a slow leak visible for as long as anyone watches; an air test can be run in freezing weather and on a leader whose base fitting cannot yet carry a column of water, and it shows a leak only as a gauge that falls, which then has to be found with soap. (17.1.2)
17.1.3 Plastic pipe shall not be air tested, and where an air test is indicated in the datasheet, plastic sections shall be water tested.
NOTE Plastic pipe fails under air pressure by fracture rather than by leak, and the stored energy of compressed air throws the fragments; a manufacturer's warranty on plastic pipe is void where the pipe has been air tested. (17.1.4)

17.2 Water Test

17.2.1 For a water test, every opening in the section shall be plugged and the section shall be filled with water to a head not less than 10 ft above the highest joint in the section, except that a leader shall be filled to its top, and the head shall be held for not less than 15 minutes with no drop in level and no visible leakage.
17.2.2 Test plugs shall be rated for the head applied and shall be restrained so that they cannot be ejected.

17.3 Air Test

17.3.1 For an air test, every opening in the section shall be plugged and the section shall be pressurized to not less than 5 psi, and the pressure shall be held for not less than 15 minutes with no drop shown on a gauge graduated in increments of not more than 0.1 psi.
17.3.2 Joints in a section under air test shall be checked with a soap solution where the gauge shows a loss.

17.4 Retesting and Acceptance

17.4.1 A section that leaks or loses head or pressure shall be repaired by remaking the joint or replacing the pipe, and shall be retested by the same method until it passes.
17.4.2 The cost of repair and retesting shall be borne by the Contractor.
17.4.3 Tests shall be witnessed by the Engineer of Record's representative and, where the permit requires it, by the Authority Having Jurisdiction's inspector, and a test not witnessed shall be repeated.
17.4.4 The Contractor shall keep a test log recording each section, the date, the method, the head or pressure at the start and the end of the hold, the result, and the witness, and shall include the log in the closeout submittals.

17.5 Roof Flood Test Coordination

17.5.1 Where the roofing is flood tested, the Contractor shall plug each drain outlet at the leader before the flood test and shall remove the plug when the roofing contractor releases the roof, and shall observe the clamp interface at each drain during the test for leakage.
NOTE The watertightness of the clamped membrane at the drain is proven by the roof flood test and not by the piping test, which does not reach the flange. (17.5.2)

18 Installation

18.1 Drain Setting

18.1.1 Roof drains and overflow drains shall be set at the low points indicated on the roof drainage plan, with the flange level in every direction, at the elevation agreed at the coordination meeting, and secured to the deck before the membrane is installed.
18.1.2 The Contractor shall verify, before the membrane is installed, that the deck and the tapered insulation layout fall to each drain, and shall report any drain that is not at the low point of its area.
NOTE A drain set an inch above its surrounding roof leaves a permanent puddle around it: the puddle is a ponding load, a breeding place, and a chronic complaint, and it cannot be fixed after the membrane is down without cutting the roof. (18.1.3)
18.1.4 Overflow drains and scuppers shall be set so that their flow lines are at the heights above the roof low point indicated in the datasheet, measured from the finished roof surface.

18.2 Protection During Construction

18.2.1 From the time a roof drain is set until the roofing is complete, the Contractor shall keep the drain outlet either connected to a leader that is open to discharge or plugged with a temporary secondary path provided, so that water cannot pond on the deck.
18.2.2 Temporary plugs and covers shall be tagged, and every temporary plug shall be removed and every dome and grate set in place before the roof is accepted.
18.2.3 Leader and pipe openings shall be capped or plugged whenever work is not in progress, so that construction debris cannot enter the piping.
18.2.4 The Contractor shall flush each leader and the horizontal piping to the building storm drain before acceptance, and shall remove any debris found at a cleanout.

18.3 Leader Connection at the Drain

18.3.1 The leader shall be joined to the drain outlet by the joint type the outlet connection and the leader material require, and the first support below the drain shall be within the support spacing this standard states for the material.
18.3.2 The connection at the drain shall be complete and tested before the ceiling below the drain is closed.

19 Delivery, Storage, and Handling

19.1 Drains, pipe, fittings, and couplings shall be delivered in the manufacturer's packaging with the markings legible and intact, and shall be inspected on receipt for cracks, spalled ends, damaged hubs, bent flanges, and deformed sockets.
19.2 Damaged material shall be rejected and removed from the site, and shall not be repaired for use.
19.3 Drains shall be stored with their domes, clamping rings, bolts, and extensions kept together by drain, so that matched components of one series are not mixed with those of another.
19.4 Pipe shall be stored off the ground on continuous dunnage, with the ends protected, and plastic pipe shall be stored out of direct sunlight.
19.5 Solvent cements, primers, and gasket lubricants shall be stored within the temperature range the manufacturer publishes and shall not be used after the expiration date on the container.
19.6 Cast iron pipe and fittings shall be handled without dropping, and a length that has been dropped shall be sounded for cracks before it is installed.

20 Warranty

20.1 Installation Warranty

20.1.1 The installation warranty period shall be as indicated in the datasheet.
Installation Warranty Periodrange
years
1235
20.1.2 The Contractor shall warrant the roof drainage installation, including the drains and their setting, the piping and joints, the hangers and supports, and the expansion provisions, against defects in materials and workmanship and against leakage for the period selected in the datasheet, beginning at substantial completion.
20.1.3 The installation warranty shall cover the labor and materials required to correct a defect, and the repair or replacement of finishes and contents damaged by leakage from a defective installation.
20.1.4 Where a warranted defect is corrected, the corrected work shall carry a fresh warranty for the full selected period from the date of correction, or the remainder of the original period, whichever ends later.
20.1.5 The warranty shall not cover leakage at the membrane clamp caused by the roofing work, which is warranted under the roofing standard, and where the parties disagree whether a leak at a drain originates in the plumbing work or the roofing work, the Engineer of Record shall make the initial determination.

20.2 Manufacturer Warranty Pass-Through

20.2.1 The Contractor shall obtain and transfer to the Owner the manufacturer warranty for every drain, expansion joint, flexible connector, and siphonic system component installed.
20.2.2 Where siphonic drainage is selected, the siphonic drain manufacturer's system performance warranty shall be obtained in the Owner's name and shall cover the priming and the capacity of the network as designed.

21 Spare Parts

21.1 The Contractor shall deliver the following spare parts to the Owner at substantial completion, packaged and labeled by drain type:
  • Two dome strainers of each dome size and material installed
  • One flat grate of each size and finish installed on decks and balconies
  • One set of clamping ring bolts for each drain series installed
  • Two removal keys or security bits where vandal-resistant domes are installed
Spare Parts Inventorycheckbox
☐ Dome strainers
☐ Deck and balcony grates
☐ Clamping ring bolt sets
☐ Vandal-resistant dome removal keys
NOTE The dome is the part of a roof drain that is lost: it is lifted off for cleaning and not replaced, or it is broken by a dropped tool, and a drain without its dome passes gravel into the leader at the next storm, so the spare on the shelf is what keeps the leader clear until a replacement is ordered. (21.2)