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Sealing a below-grade foundation wall penetration

rossn1 | Posted in General Questions on

What are the current acceptable approaches to sealing pipe penetrations through a below-grade foundation wall?

I’ve heard
1. high viscosity polyurethane
2. Low-expansion urethane foam + boot outside (fine homebuilding)
3. Other various boots

I will have a dimple membrane on the exterior.


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  1. GBA Editor
    Martin Holladay | | #1

    The dimple mat (if it is properly installed and integrated with a good footing drain) will take care of the hydrostatic pressure. If you use a high-quality caulk or European tape, you should be fine.

  2. Jon_R | | #2

    Also slanting the pipe so water is channeled outward.

    Generically, I'd favor seals that still seal with high movement - compressed foam gaskets, rubber, maybe bentonite in some special cases.

  3. Expert Member

    Pouring a sleeve into the foundation for all penetrations is the way to go. schedule 40 PVC or ABS sized to accommodate the pipe and some sealant or a gasket. That way you aren't trying to seal the pipe to concrete.

  4. rossn1 | | #4

    Thanks, guys -- all good ideas and information. Sika recommended one two-part product, and Titebond recommended their weathermaster ultimate MP, which I'm finding to be a very versatile adhesive+sealant that isn't to toxic and they report bonds well to almost everything. Since I already have some, I think I'll use that. Good ideas on the slope, sleeve, and tapes.

  5. user-2890856 | | #5

    The best products I've seen so far . Have not had one issue with these .

  6. GBA Editor
    Martin Holladay | | #6

    If GBA readers don't want to be held in suspense as they watch a video, the product that Richard is talking about is called Link-Seal. It is manufactured by GPT Industries.

    Here is a link to the relevant web page for this product: Link Seal modular seals.

  7. qofmiwok | | #7

    Does Dupont Flex Wrap work below grade? We need something faster than we can get euro tape.

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