Expert: Roger Zona - 4/10/2011

Question
Hello,
Our house was built in 2003 in Southern California.  We started experiencing moisture in our lower cabinets, as did some of our neighbors.  After years of battling the builder, we have received an insurance claim with the builder's insurance carrier.  We have moisture extrusion from the slab.  We had calcium chloride tests throughout the house with the highest number being a "9".  It was explained to us that where the moisture was able to evaporate, there was no problem.  But where the cabinets were set directly on the slab, the moisture was being trapped under the cabinets, not being able to evaporate.  That moisture is coming up through the cabinet base and creating water damage in our base cabinets.  The recommended solution was to put in French drains around the perimeter of the house and tear out all cabinets, flooring, tub, shower pan etc. and seal the slab with a concrete sealer/moisture barrier.  The sealer that is being recommended is RedGard.  I have talked with other contractors and they don't think the sealer will work.  They say that sealer keeps moisture from entering the slab but won't keep moisture from coming up through the slab or only temporarily before it fails.  We plan on putting travertine flooring in so the sealer would not be able to be re-applied.  Your opinion would be greatly appreciated.  Thanks in advance for your time and expertise.
Thanks again,
Joel

Answer
Hello Joel,

What bad luck - obviously the proper drainage system was not installed originally.  

The comments regarding a slab sealer is true.  Concrete is, by nature, a porous material and will absorb moisture.  In fact, it acts as a wick and will draw moisture up from surrounding soil if the soil is saturated.  I have experienced the trouble you describe here in Florida because our water table level is so near the surface.  

I think that the installation of a positive water drainage system would be the best solution.  First you must find out where you can drain the water.  I also suggest you discuss the problem with  a local civil engineer who is familiar with the soil conditions.  The engineer can tell you the size pipe you should use, the method of installation and suggest some local contractors to do the job.  His cost could be predicated on the contractors price.

Incidentally, travertine is a "soft" marble and it's not unusual to seal the surface.

I hope you can resolve your problem.  The moisture can can mildew and mold to form and then you have a more serious problem.  

I hope this has been a help.

Roger
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