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Subfloor over a concrete slab with wall-to-wall carpet

Chris Redacted | Posted in General Questions on

Hi I am chris, located in southern IL.
I have read a few posts about installing a sub floor on a concrete slab. I have no clue if this was built with crushed gravel  and foam before it was poured, lets assume its just old school poured nothing fancy.

This is a “workshop”, Think garage no garage door (16’x24′).
I want to make this live able space, With wall to wall carpeting.

It seems the wall to wall carpeting is just bad in slab setup.

I read about 3 options:  dricore, foam board + plywood + tap-cons, Sleepers. Seems non accomplish my goal to make it a live able space with wall to wall carpet.

I was thinking lay a water / vapor barrier  Then frame a sub floor out of 2×10 (like craw space but sitting on the slab/ vapor barrier, no block or piers), but I could not find info on spacing and how to frame it. Was reading about it might need vented like craw spaces. Then read about plastic/barriers on the slab is just inviting of mold. If I new a name for this method I could find books on it. (that is if it is a method.)

I can do the wall and ceiling, I just need to get this slab / sub floor issue sorted.

Thoughts and ideas?
Please and thanks

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  1. GBA Editor
    Martin Holladay | | #1

    It sounds as if this is an outbuilding -- not a basement.

    Step one is to address the outdoor grade. Make sure that the soil at the perimeter of the building slopes away from the building on all four sides. If there is an uphill side, you may need a swale.

    The purpose of this step is to keep rain and melting snow away from your slab.

    The next step is to install a layer of ordinary polyethylene on top of your slab, followed by a layer of rigid foam (as thick as you are willing to install, consistent with the need for fasteners that extend to the slab). Then you can install OSB or plywood subflooring, fastened through the foam to the slab below with Tapcons.

    These steps are described in the following articles:

    "Fixing a Wet Basement" (Scroll down to the section with this subhead: "Insulating an existing basement slab.")

    "Fasteners for Concrete and Brick"

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