I have a very old home that is on blocks. It was built with a 1 x 3 pine plank floor with no sub-floor. I recently remodeled and installed felt paper over the old planks then a polyfoam underlayment pad with an engineered wood floor on top. After several weeks the original wood plank floor began to cup and buckle underneath from moisture. I have now removed the expensive new flooring and am at a loss of what underlayment to use. I suspect that my problem was either evaporation from under the house or condensation from the polyfoam pad. Any suggestions?
You need to install a good plywood sub floor. Your problem was not with the underlayment as it was on top of the pine plank sub floor that buckled. Use a good 3/4 plywood subfloor with clips (to hold it together). You may be able to put it over the pine planks but it must be layed so that the seams run at a 45 degree angle to the seams of the pine planks. You would then, ideally, want the seams of the hardwood run at a 45 to the sub floor. That will make it very stable. If its a floating system use a good underlayment fabric as well.
I agree w/ sw that you need to put an additional 3/4 tongue and groove flooring down. But you put it at 90 degrees to the old 1x3. Unless the 1x3 is put on a diagonal to begin with, which I ve seen done in older houses. Then you put the new ply perpendicular to the joists below putting all end seams splitting the joists. I disagree with a poly foam for a standard engineered wood floor. Unless this is a floating floor system. Nail down systems you just use a rosin paper or felt paper under the wood. Any questions you can e mail me through my avatar. GL
