Our home was built in 1972 with wall-to-wall carpeting. We are going to install nailed down hardwood floors. We have ripped up the carpeting and found what appears to be a particle board underlayment over 3/4" plywood. Do we have to remove the underlayment or can we just lay the hardwood over the existing 3/4" ply with the underlayment on top?
Everything is in good condition.

Thanks.

Please read this:

http://www.hardwoodinstaller.com/hardwo ... .php?t=385

I have looked at this information but it does not answer MYquestion. I understand that you need a 3/4" plywood subfloor. We have that! Can we also have an underlayment on TOP of the subfloor?

You should remove the particle board underlayment and nail into your 3/4" plywood subfloor with the wood flooring running perpendicular to the direction of the floor joists/trusses. This line in the sticky mentioned not nailing into particle board.

Been there, done that on the particleboard removal. It's about as much fun as root canal without Novacaine, but it must be done if you want to put down solid flooring.