waterproof a flagstone deck

by Michael
(Greer, South Carolina)

I have a flagstone deck that was installed over a a concrete floor base which was coated with a waterproof membrane.

The deck leaks out weep holes which emit a white chalky substance which cannot be removed.

Is there a product that will "waterproof" the deck?

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flagstone roof / patio with walking traffic
by: Anonymous


I have flagstone in my back yard mainly walkways. I have a deck that has storage below whch is actually an extension of my basement. I would like to finish the top of the deck with flagstone but I'm not sure what to use as a underlayment to water proof the deck and not get leakage below in the storage area (extension of basement). Currently the deck has nothing but 3/4 inch plywood. What should go on top of the the bare 3/4 inch plywood, before I finish with flagstone and motar.

by: Michael

Dear Michael,

Efflorescence is coming out from the concrete. You can remove it using a product called SureKlean from Prosoco. You should call them for details at 1-800-255-4255. They can also recommend a good sealer for your deck.

Great luck!


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