3/4″ Naildown on Concrete

Q: Hi I have been looking at the different flooring options for a while now. It seems the widest selection is in the 3/4″ solid line. I have concrete floors and it was suggested by a friend I could lay down 3/4″ OSB after sealing the concrete to provide a suitable subfloor to nail to. Not knowing how long the nails are, I am not sure if 3/4″ would truly be suitable. What are your thoughts?
Thank you,
Gordon
A: You could glue down OSB or plywood to the concrete, then nail, but this has a high chance of failure. Your best bet is to build a breathable subfloor over the concrete from treated lumber and OSB or plywood.
What you will need to do is glue and shoot treated lumber (usually 2x4s) in place with concrete nails and a good adhesive into place to act as sleepers. To save a few bucks, you can cut the 2x4s in half, but make sure you treat the cut side. You will want to use 12″ centers here to ensure stability and still allow the floor plenty of breathing room. From here install the base of your subfloor into your sleepers. Then from here you will install your flooring as you would normally, nailing it over the new wooden subfloor you have constructed. If this is planned for early on, its actually very affordable (about the same cost as gluing down a floor) and will provide an excellent subfloor that should stand up for years.
Keep in mind that gluing a 3/4″ solid directly to the subfloor is a BAD idea. Should any moisture get into the flooring, it will be game over. Plain and simple, 3/4″ moves the most of all flooring (expansion and contraction) and when this movement occurs with a glue down application the floor will warp and buckle. Glue down applications allow for minimal amounts of movement by nature.