Siphonic Roof Drain

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Siphonic Roof Drain

Figure Number:  1005
Labor Saving

Smaller Pipe Diameter, Single Point of Discharge,Reduced Material Cost, Eliminates Slab Penetration Costs.

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Fatiguing drain lines have the potential to cause serious problems if they fail. Even if no work could be done inside or under the facility, a great option is to tackle the problem overhead using a siphonic system. The solution solves the problem without disrupting anything in the facility or cutting into concrete to run piping to the storm culvert.

Pro Tip:
The siphonic drain is just one component in a siphonic drainage system. These systems should always have the approval of a plumbing engineer, licensed in the locale where the installation is to occur.

Product Function:
For use in engineered siphonic roof drainage system. May be used in flat roof of any construction. Large low profile dome provides sufficient free area for quick drainage of rain water and protects the drain sump, baffle and connected piping from the intrusion of debris. Internal air baffle creates siphonic drainage action producing more efficient drainage than traditional roof drains.

Contactor Friendly and Labor Saving Features:
  • Full-bore flow within the piping reduces pipe diameter as compared to open channel, traditional gravity flow, which operates at 1/2 the capacity.
  • Siphonic action is independent of pipe pitch or gradient. Horizontal piping is not pitched. The invert leaving the building is eliminated.
  • Smaller pipe diameters allows maximum use of open space without intrusion of drainage piping. This also reduces material costs.
  • The point of discharge for the roof can be concentrated to one corner, typically, rather than out of the building in several points.
  • Slab installation costs are minimized, reducing excavation, backfill coasts, and exterior underground piping
  • Siphonic systems promote self-cleaning of debris from the piping system
  • Fully tested and certified in accordance with ANSI/ASTM A112.6.9 “Siphonic Roof Drains”

Green Building Feature:
  • Flexibility of Stack Placement-The ability to run drainage pipe horizontally overhead gives the designer the opportunity to combine several drains into one manifold and one stack. So it is possible for a building's roof drain system to use one eight inch stack (just for example) instead of three eight inch stacks . Being able to design the location of the stack(s) aides in the design of a rainwater harvesting system, a Green Building solution.

Regularly Furnished:
Duco Cast Iron Body, Flashing Clamp, Air Baffle and Polyethylene Dome.
Product Details
  • Product Type:  Roof Drain
  • Benefit:  Labor Saving
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NameDescriptionFile Size
Specifications US Govt ComplianceItems complying with U.S. government specifications34 KBDownload
CSI Specifications for Roof DrainsCSI Specifications for Roof Drains230 KB
NameDescriptionFile Size
Parts Order Guide for Roof DrainsParts Order Guide for Roof Drains632 KBView

Optional Materials

  • Aluminum Dome -AD
  • Cast Iron Dome -CID
  • Galvanized Cast Iron Dome -CIDG
  • Galvanized Cast Iron -G
  • Rough Bronze Dome -RBD


  • Sump Receiver -R
  • Underdeck Clamp -C
  • Underdeck Clamp for 10" Deck Opening -C10
  • L-Shaped Underdeck Clamp -CL
  • Vandal Proof - Dome - U