Exterior flagstone landing

by Allan
(Los Angeles, CA)

I have an exterior flagstone landing above an interior room. Normal to heavy rain isn't a problem, however, when it rains constantly and heavily for days, water seeps down into the ceiling of the room below. I suspect the problem stems from the issue of rain buildup absorbed by the stone and eventually working it's way through. Is there a sealer that might prevent this problem?

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membrane
by: David

Dear Allan,

That could be a big problem. Whenever you lay stone over another room, you need to install a rubber membrane that keeps water from seeping through.

With a lot of rain, the water will work its way through the stone and concrete and cause your leaks. I doubt that a sealer will solve that problem. However, give Prosoco a call at 1-800-255-4255 and inquire if they have a strong sealer for that kind of situation.

If they don't, the only thing I can think of is putting a plastic tarp over your stone any time a big rain is coming. I know that doesn't sound appealing, but I can't think of anything else short of tearing the stone out and re-installing it.

Great luck with your project!

David

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