Expert: Len Kroll - 5/9/2005

Question
Dear Mr. Kroll,

I really like the solid hard wood planks compared to the engineered. Some companies said it's okay to lay solid planks down on cement slab as long as there's a water barrier and some said otherwise. We live in San Diego Ca. Please advice.
Thank you.
Phyllis  

Answer
Phyllis,

You can lay hard wood floors on concrete.  Here's how we do it.

First we use a liquid concrete sealer painted on the surface of the concrete slab.  Then we lay 15# felt paper on the entire slab overlapped 4" and duct taped to seal completely.  

Next we lay 1x4 or 2x4 sleepers 16" on center; then lay 4x8-3/4 Advantech OSB sheets glued and nailed to the sleepers.  Last we lay another layer of 15# felt on top of the OSB to prevent squeaking which develops when the hard wood and OSB rub against each as walked on.

Now you are ready to lay the hard wood floor on top of the sub floor.  The entire floor is a "floating floor."  Be sure to leave about 1/2" space all around the perimeter to allow expansion and contraction without buckling.

You will need to check the levelness of the slab before you start.  If there are hills and valleys you will need to level them out.  If there are only a very few we would usually simply shim the sleepers.  If there are a lot or if they are large we usually level with a concrete leveling compound.  Some professional flooring contractors use fine sand to level a slab.

Good luck.

Len Kroll
Wood House Construction, Inc.
800-864-6701