@R2unit posted:As others have stated, I too have 1/2" birch plywood with Homasote glued and screwed with sheetrock screws on top. No issues at all. One thing I did notice is that I saved some pieces of Homasote from my previous layout and when mating them together with the new homasote on the new layout there was a slight difference in thickness. Also some of my sheets do have thickness variations throughout the the same sheet, although not enough to take notice. I purchased mine at Lowes here in upstate NY.
I did notice some slight variation in thickness, but no more that about 1/16". I got all 12 sheets of mine from the same pallet at HD, only rejecting pieces that were damaged in handling. They even cracked a new bundle for me since they only had a few mothy sheets that weren't bundled. Overall, I'm very happy with the Homasote base, and a bonus is it holds the track screws very well. As long as you don't screw into the plywood under it, no issue with noise transmission.
