Q: I have a very good customer of mine that is adamant about installing unfinished oak strip 4′ x 3/4′ in a basement. I have advised him to use laminate in this situation, however he wants real wood. What is the best method to install a plywood sub-floor for real strip hardwood?
A: I’m with you on this one. No manufacturer will warranty it against water or moisture damage. I would make sure your customer knows and understands all this. Best way to do this? I don’t know if this is a best way, but first I would check the concrete floor, assuming it is concrete, for any signs of moisture. Do several tests in random areas around the floor. Check the walls too if they are not covered. I believe Bostik sells a sealant for concrete which I would have a look at. Apply that first. Then lay out Delta sheeting and screw minimum 3/4 ply over that. A job like this can be successful, but there are issues that can impact the floor which we may not even think about. How is the grading in the yard? Will water tend to flow toward the house, rather than be diverted away? If the basement feels damp, as many do, he may need to have a dehumidifier running constantly.
If you come up with any other ideas, let me know. Last time I was involved in a solid wood floor install in a basement, the home owner rejected the engineered idea because he wanted solid wood. A month later the floor was cupped. This was years ago, however, and in hind sight, was partly my fault. He had 2 floods previously from his washing machine and he had a raised plywood subfloor which had no ventilation under it. I didn’t own a moisture meter at the time, but since the plywood felt dry, I assumed it was. Big mistake. Assume nothing. If I walked into a job like that now, the first thing I would do is replace the sleeper/sub floor system.