I own a condo in California on the second floor. I’m looking to replace my carpeting with engineered wood flooring. I pulled up the carpet edge to see what type of subflooring I have and the subfloor seems to be a brittle dirty white stuff like concrete, but not nearly so solid. I found out that the contractor used Gyp-Crete

http://www.maxxon.com/gyp-crete/data as floor underlayment to muffle the sound.

I want to do a nail down application of the engineered wood and am wondering if this is possible or do I have to go with glue down.

Thanks for the help!!!

Golly, two in one night!

Use this product: http://www.ardex.com/productDetail.asp? ... oductID=16

With a very pourous, loose subfloor like your talking about, apply more than one coat of the Ardex primer.

With that substrate, I would not glue or try to fasten anything to the gypcrete.

Floating subfloor, or floating installation, only. Or I let someone else risk it and walk away.