I was thinking about replacing the carpet in my dining room with engineered hardwood flooring. The room is about 12' x 12'.
First thing I noticed is that I have 5/8" OSB subfloor, and pretty much all flooring manufacturers say this is not adequate. I should be able to add 3/8" plywood on top of the subfloor without height issues. Should the plywood be glued to the subfloor and screwed to the joists? A lot of what I have read said to screw or nail only, and only to the subfloor, but I have difficulty understanding the reasoning. The joists are on 16" centers, and this is on main floor (no moisture issues). I have not noticed any squeeks or movement in the flooring.
Next question is what is best method for attaching the flooring to the subfloor? Seems many of the engineered flooring are rated for nail, glue, or floating. Originally, I was thinking floating, so that the wood is free to move with temperature/humidity changes, but now I am leaning towards gluing it down, since I am starting to get concerned about having too many layers of flooring.
5/8 would be the bare minimum for carpet or linoleum.
Unless this was really wide engineered floor I would not glue it.
Only time I would install it as a floating floor is if it was installed over a slab.
Best way is to nail or staple it!
Just curious why you do not like floating engineered flooring unless over a slab? I just floated a floor in a bedroom. I figured it will make things a lot easier if we ever decide to change things up in the future.