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Poured Concrete Wall Moisture Control

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  • Poured Concrete Wall Moisture Control

    Hi
    I'm a contractor in the early stages of a basement remodel on a 1921 Craftsman w a poured concrete foundation. After demo of the old framing & paneling, the foundation wall condition is concerning. In talking with the owner, there's been no standing water in the basement, but there has been "dampness" (as well as moldy framing/paneling).
    - There are about 6-8 vertical cracks in various locations, about 3/16th inch wide max. Lots of efflorescence concentrated in these areas, mostly on the walls. (& spiders, lots of spiders.)
    - There's no evidence of running water, & the exterior has been re-graded about 5-6 yrs ago.
    - There's peeling paint on the concrete walls, as well as some spalling.
    - The floor is in good shape with only minimal cracking. No staining.
    - I tested the wall surface (taped plastic on the wall) to determine the water source, & it was wet on the wall side.
    - Radon tested positive.
    - This is a city lot, & there' no access to the wall's exterior surface.

    My sense is that installing drain tile w sump is overkill since there's no running water. It all seems vapor migration. The initial plan was to use 2" rigid insulation w sealed joints behind 2x4 framing on a sealed PT plate, per code. But I have a real concern that'll only seal in moisture coming from the walls. If the vapor is sealed in, a de-humidifier system is pointless.
    Some Qs:
    - Is there a way (or system) to dehumidify the air BEHIND the wall? Or, is there a way to allow the vapor thru & still satisfy bldg code?(Do I slice the joints after inspctn?)
    - Does anyone have positive experience with the epoxy/polyur crack fillers, or concrete sealers (RadonSeal, Enduroseal, Emecole)? Anything that works on painted walls, or is there sand-blasting in my future?

    I appreciate any of your thoughts(and prayers). Thx.
    Todd

  • #2
    Re: Poured Concrete Wall Moisture Control

    Is the poured foundation really from 1921? Doesn't matter but that was my first thought when I read this.

    If you have moldy framing and positive radon the drain tile should be a "must have" IMO. I'm guessing, based on your description, that the basement is about 500-900 square feet? Probably 5 grand for drain/sump/radon, maybe a little more. Mark it up and sell it,you will never worry about it when it rains 2" in 24 hours.

    Don't slice open anything and what happens between the 2" rigid foam and the foundation doesn't matter if it is draining to tile.

    Not to be rude but do you really think anyone is "praying" for your basement remodel?

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    • #3
      Re: Poured Concrete Wall Moisture Control

      Yeah, I'm thinking concrete foundation walls in 1921 would be rare. Maybe it was some kind of parging added later. Can't say I've ever seen concrete foundation walls spalling, either, but I don't know what kind of concrete it is.

      There are only 2 things I would do. 1. Drain tile, then wait and see if it dries out. If not, 2. Create a vented space at the wall surface and space the framing/insulation away from it.

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