I'd like to install solid 3/4" hickory or tigerwood floors, but would like an opinion on my subfloor. The floor joists are 2 x 12. There is 3/4" plywood installed over the floor joists and 3/4" Duraflake (a MDF board, not particle board) floor underlayment over the plywood. Should the Duraflake be removed and new 3/4" plywood be installed or is ok to nail through it. The new flooring will run both with and perpendicular to the floor joists (different rooms). Thanks...

Damon

I would remove the MDF, otherwise your not going to get adequate grab with the fasteners. Sheeting out over the 3/4 ply with 1/2" CDX is sufficient for installing parallel to joists, and makes for a stout subfloor.

Based on your response, I take it using longer nails or staples is not an option? Don't misinterpret what I'm saying. I do not want to cut corners and regret it down the road. I also do not want to create extra work and expense if unnessary. Thanks for your insight.

Damon

May work, but not a common practice over 3/4" ( NWFA doesn't advice this practice).I'll stretch the rules sometimes, maybe 1/4" masonite or similar,( thats over 3/4" Ply or OSB). IMO it's too thick sinking through a membrane of 3/4" material like MDF in order to achieve adequate grab in the plywood. Also, I believe the max any flooring nailer will shoot is a 2" fastener. Figuring the toenail angle your not going to get the grab.