my 20x30 plans call for a 3/4 plywood decking, would 1 1/8 be overkill or unnecessary?
it cost 10 more dollars a sheet.
It would not add much structurally. The 3/4" subfloor is designed to work with the joists. On the other hand it doesn't really hurt either (maybe more time spent behind the drill for wiring and plumbing) and would probably stiffen the floor.
Thank you John
Just for your info, I just finished the main floor for my 20 x 30 1-1/2 cottage. One of my concerns was floor bounce spanning the 18' 9" (8 " concrete wall w/ 2x8 sole plate). I used the 3/4 TNG, glued and screwed this down and I am very happy with the floor stiffness.
Russ
Thank you Sourdo