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Temporary cover for basement insulation

Noah Harper | Posted in General Questions on

I recently bought a home in Wisconsin with a partially finished basement. That is, the walls are studded out about 1″ from the concrete and there are bats of fiberglass insulation between the studs. I’m not planning to finish the basement in the next year or two, and was wondering what a good temporary cover could be to put on the walls that I could do pretty quickly so that I could use the space as a workshop and gym. The perimeter is about 120′ with ~8′ tall ceilings, so I’m definitely looking for a material on the cheaper side. Initially, I had planned to put up plastic, but after a little reading that sounds destructive due to keeping vapor from passing through. A couple options I’ve thought of are house wrap, or a thick breathable contractor’s paper. Any recommendations?

More info on the basement:
From the paperwork, it appears to be insulated from the exterior with a layer of foam insulation, a waterproof layer, then the foundation itself. The basement appears to be quite dry and has shown no signs of leaking even in a couple heavy rainstorms lasting several days. The studded walls with bats sounds like a regrettable setup after reading the guides here and elsewhere, so I’m not sure what I’ll eventually do for finishing it, but I’m okay with figuring that out at a later date when I have more bandwidth.

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Replies

  1. Expert Member
    Dana Dorsett | | #1

    Even if you're not planning on finishing the basement any time soon it's well worth AIR SEALING and INSULATING the basement in a manner that isn't an energy leak or a risking becoming a mold farm.

    IRC code-minimum would be R15 continuous insulation, and what's there is nowhere close to that. With no back-side air barrier facing a 1" air gap (aka "thermal bypass" ) the batts are performing at nowhere near their labeled R.

    Is this house in southern WI (climate zone 6) or is it northern WI ( zone 7)?

  2. Noah Harper | | #2

    This is in southern WI.

    So assuming I do something along the lines of what has been recommended to others in similar threads in the past, such as a layer of sealed foam board, reinstall the studs and bats, is there something I could temporarily cover that with? Or, would it be crucial to install gypsum board to actually get it properly sealed? What I'm trying to avoid for now is doing electric, inspections, permits, etc. since that would consume additional time and money.

    1. Expert Member
      Dana Dorsett | | #4

      What Matt_F said.

      Take out the studwall, if yo uhave space, save the batts stacked up on on pallets off the floor for re-use later with at least a couple inches of space to the walls, and install 1.5" (or more) of Dow Thermax fire-rated polyiso. It goes up pretty fast. (Leave an inch between the bottom edge and the slab to prevent moisture wicking into the polyiso foam.)

      Then as time allows re-install the studwall tight to the wall foam, and re- insulate using the batts when you're ready to put up the wallboard. In zone 6, with with 1.5" (R9) polyiso there is sufficient dew point control at the above-grade section for up to R15 of batt using just standard interior latex paint on drywall as the vapor retarder.

      At 1.5" Thermax would be outperforming a 2x4 studwall that has no interior or exterior side air barriers.

      I'm assuming the exterior insulation stops at grade, and does NOT continue all the way to the top of the foundation(?).

      1. Matt F | | #5

        Dana, do you think it would be worth digging down to see what the exterior insulation is and if it is sufficient, continuing it up the exterior wall? Probably similar work to taking down and reassembling the interior wall, but with the issue of detailing exterior foam.

        I just watched a new foundation go in around the corner from me where they put exterior insulation up the entire foundation and then cut it back to grade after back filling...

  3. Matt F | | #3

    Per code you need a thermal barrier over the foam. Drywall is as cheap as any other option I am aware of. The other option would be using Dow Thermax polyiso, which is rated as a thermal barrier on its own.

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