Squeeks are caused by rubbing (nail to wood or wood to wood) and causes the boards to resonate. That's what you hear. Certainly screwing the floorboards from underneath is better, etc, but the application of drywall and damping material to the underside of the subfloor will damp the wood resonance dramatically.
However it's always best to treat the actual problem, rather than the symptom. So I would not omit screwing and shimming.
The decoupling of the drywall from the joists will help with the PJ vibrating with footfall.
However it's always best to treat the actual problem, rather than the symptom. So I would not omit screwing and shimming.
The decoupling of the drywall from the joists will help with the PJ vibrating with footfall.





















