Is it Ok to seal a concrete floor with Kilz and then install carpet over it.


Is it Ok to seal a concrete floor with Kilz and then install carpet over it.

Asked by M Tilly

We just bought a house and the family room carpet had pet urine on it so we ripped it out. We are wondering if we should seal the concrete floor with Kilz to make sure all the odor is removed before we put carpet over it. Or will sealing it make the carpet retain moisture and possible mold underneath?

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Harold Remlinger, AIA, LEED AP, NCARB's picture

Lets start with the question regarding moisture first. Since you are a slab on grade construction, per code there should be a vapor/moisture barrier installed between grade and bottom of the concrete slab. With that said, any moisture below the carpet would remain below the carpet unless removed. Next, mold needs a food source and continuous moisture to grow. Assuming a vapor barrier is installed below the concrete slab, the only source of moisture would be due to leaks and continuous flooding. If neither of these items exist, mold will not grow. You can test to see if a moisture barrier is installed by taking a 12" x 12" piece of plastic drop cloth and tape it to the concrete slab with duct tape. If moisture forms between the slab and plastic you do not have a vapor barrier. As for sealing the concrete, I would use a Sherman Williams of equivalent concrete sealer. Verify that this sealer compatible with the carpet adhesive.