I was told by my flooring guy I could install real wood flooring in the basement as long as I put down 3/4 " plywood first. Is this correct. If I use 11/16 " T&G will the standard hardwood flooring nails be too long?

 

Depends on what you mean by "real" wood, and where you live.

3/4" is too thin for nail-down or staple-down flooring. You'll either need two layers of 1/2", or you'll need to put that 3/4" down on sleepers to allow the nails to penetrate it.

If by "real" you mean 3/4" solid, then be aware that no flooring manufacturer will honor the warranty on a solid hardwood installed below grade. However, if you live in a very dry climate, you might go ahead and take the risk anyway.

The normal solution is to install engineered hardwood (not "laminate" flooring), either floating or glued down (depends on manufacturer). This type of flooring is ideal for a basement. It will look and perform identically to solid hardwood. Get a kind with a thick layer of hardwood on it (not just a 1/16" veneer, but a 1/8" to 1/4" layer) so that you can refinish it if needed.

 

Ok, I have decided to take your advice and put in engineered wood flooring. The click together kind. The recommended underlayment cost more than 3/4 inch OSB (which I already have). Do you think the 3/4 inch OSB and a plastic film would be as good or better than the thick plastic underlayment that is made for floating floors?