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Community and Q&A

Basement floor options?

cord12 | Posted in Green Building Techniques on


We are retrofitting our finished walkout basement in zone 7 WI and are looking at floor options. The slab is not insulated but does have poly plastic vapor barrier over pea gravel under it. Soil under the pea gravel is sand to sand/silt. We have an active radon system connected to the perimeter drain system. The sump pit has always been dry since the house was built (15 years). We do run a dehumidifier.  

Padded carpeting is currently covering most of the floor areas. We plan to remove the carpeting and then likely install a subfloor of EPS followed by plywood. We have questions on the stack up of the EPS and plywood regarding the existing finished walls (both interior and exterior). Currently, the walls bottom plates are treated 2x4s covered with drywall to approximately ½” of the concrete floor. Do we need to cut the drywall a little higher so that it is not entrapped by the subfloor EPS and plywood stack up? If so, the drywall will now be higher than the 2×4 bottom plate breaking the drywall air seal on the exterior walk out wall.

We would also like recommendations on a new floor covering. It seems it should be vapor permeable, so as not to entrap moisture in the EPS and plywood subfloor. We don’t want carpeting but rather a hard surface that is easy to clean.

Thank you, David

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  1. Expert Member
    Peter Yost | | #1

    Hi David -

    I would definitely trim the dry wall up so that you have a moisture break between porous building materials.

    In terms of vapor permeable hard surfaces for the basement finished floor: in our basement we chose to paint the concrete and then use rugs instead of carpet. You get the softer surface where you need it and simply pull all the rugs from the basement floor during one or two excellent drying days a year to air them out.


  2. cord12 | | #2

    Thank you Peter!

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