How to Choose a Menzies Roof Drain

You may notice that many of our roof drains look quite similar. Which one do you choose for a roofing project? Are the differences between them important? Yes, they are. Each drain is designed for a specific application and to serve a specific function. Here’s how to choose.

First consider the roofing material you will be installing. With modified bitumen or EPDM, you will want a clamping ring to secure the membrane at the drain bowl. You want the water to go into the bowl, not under the membrane. Our Clamp-Tite Spun Copper Drain family will meet your needs. With TPO you may choose not to use a clamping ring. Our Direct Weld™ TPO coating on the drain flange allows you to securely weld directly to the drain since the flange IS TPO. Non-clamping ring TPO coated drains include the Value Drain and Commercial Drain. Non-clamping drains for TPO are an accepted standard. So: mod/bit or EPDM, clamping ring. TPO, not necessarily.

  Clamp-Tite Spun Copper Drain:    drain

  Value Drain:

  Commercial Drain:

Bowl size may be an important consideration on a re-roof. It would be best to simply slide the re-roof (insert) drain down into the existing drain bowl. The new drain must fit flush on the roof surface inside the old drain bowl and the new outlet pipe must fit inside the old outlet pipe. The old bowl may be a little (or a lot) too shallow for this. In that case you would use one of our smaller bowl drains. The Clamp-Tite Small Bowl, Commercial Drain and Value Drains are designed to meet this purpose. Perhaps this is a concrete deck with no bowl possible, only a hole the size of the outlet pipe. You could use our Commercial Undersize Drain, which has no bowl.

  Clamp-Tite Small Bowl:

  Commercial Undersize Drain:

Insert drains are typically made with pipe OD ¼” less than the outlet pipe size. A 3” insert drain will have a 2 ¾” OD. This is so they will slide in but still be easy to seal. There are cases where this won’t quite fit. But where a 2 ¾” OD won’t fit, a 2 5/8” OD might. That would be our Commercial Undersize Drain, where a 3” drain has a 2 5/8” OD.

You must also consider what kind of connection seal to the outlet pipe there is to be made. Our insert drains come standard with a heavy duty rubber O-ring, sealing between the drain stem pipe and the outlet pipe. For 3”, 4”, 5” and 6” insert sizes the Blue Drain Seal is an excellent choice. It provides a secure mechanical seal by expanding the rubber sides against the drain stem pipe as well as against the wall of the outlet pipe. This seal is performed by the installer above the roof deck, with final tightening done just before the strainer is put in place. The Blue Drain Seal is listed for approval in Canada and the U.S. and far exceeds testing requirements for the standards. For under deck connections with a no hub coupler, also called an MJ coupler, use our Clamp-Tite Copper No Hub Drain. The no hub system, a heavy rubber coupler secured with stainless steel hose clamps, allows for a strong connection while tolerating some movement/settling of the roof deck.

  Blue Drain Seal:

  Clamp-Tite Copper No Hub Drain:

The majority of our drains have been laboratory tested by QAI, an independent third-party testing, inspection and certification organization, and are listed as meeting the applicable Standards in Canada and the U.S. These drains include the laboratory mark and Standard references to satisfy the building officials. All these drains can be compared on our website. Menzies drain approval listings are available here: These are quality products and if you have read this far you should now know which one is appropriate for your application.