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Community and Q&A

Airtighting a drain to daylight?

Mark Harrison | Posted in Green Building Techniques on

We are building a reasonably airtight house.

We plan to install a floor drain with the discharge set up as drain-to-daylight.  I am concerned the the trap might not always have water in it, which would create an air leak. 

Is there a practical way to achieve a reliable air barrier for this drain?  (I am thinking of something like a spring-loaded flapper valve at the daylight end . . . )

Suggestions?

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Replies

  1. Expert Member
    Malcolm Taylor | | #1

    Mark,
    Several companies sell a back-flow preventer that works as you describe. One is the (unfortunately named) Rectorseal:
    https://www.rectorseal.com/sureseal-trap-seal/

  2. thrifttrust | | #2

    Self priming traps are available that periodically introduce a small amount of water into the trap.

    Douglas Higden

  3. Scott K | | #3

    Our drains to daylight don't have P traps. Not exactly sure why, but I had the same concern with our 3 garage drains to daylight. I used these https://www.amazon.com/gp/product/B00W2FQX2U/ref=oh_aui_search_detailpage?ie=UTF8&psc=1 which are similar to the "Sure Seal" product above. We aren't living in our house yet, so I can't speak to their effectiveness, but it appears they will work well.

  4. Expert Member
    Malcolm Taylor | | #4

    Scott,

    P-traps are typically used on drains connected to sewer systems to stop gas from venting into the house. Floor drains to daylight often don't have P-traps, although it's a good idea both to stop pests using it as an entry point, and for air-sealing where that matters.

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