I recently installed 5 inch 3/8 inch thick engineered hardwood in my house. I tried to screw down subfloor to remove squeaks but some persisted. I suspect that at this point my best bet is to open the ceiling below and use squeak enders to pull the subfloor to the joists. What I've noticed though is that I have two kinds of noises. I've got the high pitch squeak that I heard before putting down the floor, as well as a lower pitched creak in some other areas. Could that be from boards that maybe were bowed, moving up and down and rubbing on the staples I used to install. If so, what's my best course of action to stop it? I don't think I can screw up through subfloor even if I opened the ceiling below, the floor seems too thin to catch a screw well even if I managed to put it to just the right depth (which seems tricky). Thoughts?