Subflooring damaged causing creaking and squeaking

Q: I recently installed 3/4″ x 4″ prefinished maple planking in my home. I used coated staples and rosin paper. The flooring looks great, but I now have a problem in my kitchen. To accommodate the flooring, I tore out ceramic tile and a layer of Luann. That left the plywood underlayment which worked fine in the other rooms where only carpet covered the floors. In the kitchen, however, the screw holes and glue that held down the Luann appears to have sufficiently damaged the plywood and affected installation – I get creaks and squeaks in a lot of places and especially in the most marked up areas of the plywood subfloor.

In my opinion, the integrity of the subfloor was damaged enough so that the staples do not hold well. I should have repaired the floor, added a new layer of subflooring and then installed. I have access to the floor from the basement and tried screwing the flooring down from below, but that only worked in some spots. The problem is too acute to use this approach effectively.

I noticed the reference to the injectable glue in a post on a website. Would that work?

A: The injectable adhesive won’t work, because the floor has rosin paper under it. Next best solution in my view would be to remove individual boards, cut out the rosin paper, spread some urethane adhesive, such as Bostik’s Best. cut the new board to length, removing the bottom edge of the groove side and groove end. Drop the board into place and either face nail or weight it down until the adhesive dries. I would try to carefully remove the entire floor and re install it before I would put laminate over top.

Just for informational purposes, you might even find inject able adhesives on the Bostik-Findley web site. I believe a company called Vermeister also makes such a product. I have discovered a good moisture cure urethane adhesive at Home Depot in a squeeze bottle. You would have to find a way to get it to the bottom of the board. Perhaps a long tube attached to the end of the bottle in the smallest diameter that works. This would likely require a slightly bigger hole of perhaps 1/8 to 3/16 which could be putty filled after. With this product, you would have to tape around the hold to prevent the adhesive from getting on the floor surface. It expands as it cures, and would likely foam up out of the hole. You don’t want it getting on the floor surface. After it is dry, you can cut off any outpouring with an exacto knife. Not that this will help your situation, given the paper beneath the floor. But one possible solution in other circumstances.