Expert: Bruce E. Johnson - 9/3/2010

Question
I built a 36' x 36' pole building with a concrete slab last winter. I still have moisture on the floor if the doors are closed 2 or 3 days. I frenched drained along the back because of obvious water coming out of the hill that was cut into for the building. Im guessing theres a water table under the slab? What would be the best way to take care of the problem?

Answer
Hi Ron, you didn't say whether or not you installed a vapor barrier underneath your slab prior to pouring the concrete.  If the moisture is coming up through the floor and you did not install a visqueen barrier there are some concrete sealers available that will seal the slab from the top down. Following is a link to one such product.

http://www.bonedryproducts.com/concrete-sealer.aspx

It may be possible that the air is moist and is condensing on the floor. This would be unusual unless you live in a wet climate with high humidity.  You can check your humidity inside the building with a simple device purchased at most hardware stores for less than 20 dollars.  Normal humidity should be around 45-55%, if your humdidity inside the closed up shop exceeds this and is in the 70 or 80%  range or higher you might want to consider a dehumdifier or air conditioner to help keep the humidity levels down.

I hope this information helps please feel free to write again regarding this or other matters, sincerely bruce e johnson..bejohnsonconsulting.com