Question from Ronda
We are moving into a house that is 22 years old. We are taking out all the carpet and replacing it with prefinished hardwood.
Should we rip out all the plywood (maybe MDF) and glue the hardwood to the concrete or do you think it would have completely out gassed by now and is safe to leave in?
Also, the moisture barriers that I’ve seen today are in a liqued form that are brushed on the concrete. How do I know if the liquid moisture barrier is safe? Lumber Liquidators uses a brand called Mapei for their adhesives and liqued moisture barrier.
Thanks so much for all your wonderful help!!
Debra’s Answer
After 22 years, if you want to leave the plywood in place, I think it would be fine. It would offer more cushioning than applying the hardwood directly to cement. And if you are installing the wood with glue, the glue will form a barrier that would block any outgassing of the plywood (if you completely cover the plywood with glue).
I hope you are using a nontoxic, water-based “woodworking glue” to glue the wood down.
Re the moisture barrier, take a look at the MSDS sheet for hazardous ingredients. I have installed wood floors with wood glue over cement without using any moisture barrier of any kind and it was fine.
