I'm looking at having a new home built and I'm nervous about the strength and thickness of the subfloor. The builder uses 5/8 OSB over an engineered floor joist system where joists can be between 12" and 19.2" OC. I asked for 1" subfloor and the builder thought I was nuts. My main reason was I didn't want the floor feeling "cheap" in 15-20 years. The builder indicated he could price out 3/4" OSB instead of 5/8 OSB but that I wouldn't get any increased stiffness from 1" and that his supplier doesn't sell 1" OSB anyway. I can't imagine a floor being that thin, however! Will I be happy with my floors in 15-20 years? What do you recommend? What would you use yourself in your own new home?
My understanding is that the subfloors will be glued and screwed. But he said that he screws are placed every 12". Shouldn't they be closer than that?
Floor types: I'm getting basic cushion flooring in the kitchen, some hardwood in a hallway, ceramic in the entry, and basic carpet elsewhere. What sorts of underlayments should be present underneath these different floorings and what thicknesses should they be?
Answer:
For your fist consideration, I'd look for another builder because 5/8 OSB is certainly not enough. Engineered joists are very firm indeed but you'll get squeaks of all kinds if you put material over them that was mean to span less than 19 inches. 7/8 OSB is available and I would still insist that the engineered joists be 16" O.C.
Fasteners for sub-flooring are best applied every 6 to 8 inches in the field of the 4X8 sheet and every 3 to 4-inches along the butted edges.
You'll have to have at least an inche and a half of wood under your ceramics but elsewhere, your finished flooring material will dictate what you have to have for underlayment; and I mean 'dictate' because unless you do things according to manufacturer's (not contractor's necessarily) specifications, you have no warranty.
