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Wet floors

by Depressed home owner
(Snohomish Wa)

Q. I just bought a house that has a brand new detached garage/shop (1500sq ft). Unfortunately during construction of the shop,they did not lay a vapor barrior prior to pouring the slab. During winter the water table rises where the shop is built and water sweats up throught the floor like nothing I've ever seen. When the shop was first built a clear sealant was painted on the floor but the sealant has bubbled up and pealed away like skin from a bad sun burn and no longer exists. If you place a rubber floor mat on the cement for an hour, when you pick it up water drips from the floormat and the floor where it was laid is wet to the touch. What are my options to seal/waterproof this concrete so this does not continue to be an issue? Someone suggested swimming pool paint. I just want something that will seal the floor permanently.

A. You should try applying a penetrating concrete sealer, also called concrete densifier. It's a silicone based sealer that penetrates the pores of the concrete and reacts with the free lime. This reaction creates a gel like substance that fills in the pores and capillaries. The gel hardens making the concrete more dense, thus preventing moisture from moving up through the concrete. You can only find this type of sealer at concrete/masonry supply stores. Also, you'll have to wait until the dry time of year when the hydrostatic pressure is at it's lowest. Hydrostatic pressure is the force created by water being pushed up from the subgrade.