The facts: new house, floor installed May 2004, oak floor over 3/4 OSB, trusses on 24" center parallel to flooring (a no-no, from what I've already learned), gas heat with humidifier, 2 story house + basement, in Virginia

There are squeaks throughout the house, and the flooring contractor came back last month and installed screws to pull down the flooring. While this stopped some squeaks, the others just moved. In all, he put in nearly 2 boxes of screws.

The floor has also developed cracks throughout the house. Some, but not all, of the individual boards have started pulling apart. There are actually gaps on the sides and ends of the boards. My real concern is that these are continuing to grow during the summer months, what will happen in the winter? The builder brought in another flooring contractor, who said that there is nothing that can be done for the squeaks, and the cracks are "within toloerence". Are there defined tolerences that say, for example, 1/64 is ok, 1/32" is unacceptable?

Is this floor a floor that was sanded and finished in place? If so, the gaps could be filled and another coat of finish applied, after proper preparation. If this is a factory finished floor, it most likely has micro bevels which conceal the gaps to a degree. There are fillers available for those floors as well. My biggest concern was having the floor laid parallell to the trusses (joists) which were installed 24" oc. Now, I know for certain that the flooring is deflecting between those trusses and that could be the cause of some of the gapping. The few times I have run across 3/4" subfloors installed 24" oc, I stipulate that another layer of 1/2" plywood needs to be installed. Why? Because although that span is permitted by codes, it is not stiff enough for wood or tile flooring. The constant flexing plays havoc on the floor covering. An 1/2" CDX plywood underlayment should have been installed over the 3/4" OSB before installing the hardwood.

Yikes!

I agree with Gary. That subfloor needed to be addressed before the installation started.

Deflection, loosens the fasteners hold no matter which diretion the floor is running. Squeak squeak, squeak!

If the floor can be acessed from below you can cut a bunch of cross blocks to reinforce the trusses which will take care of some of that deflection.

I'm with Kevin on this one. Creaks/Squeaks are the result of movement. Support the subfloor to minimize movement. Sounds to me like this home or subfloor has moved, shrank, settled.. Probobly not due to improper nailing of the wood to the subfloor, but problems with the subfloor to the joists. Support makes sense and the entire home will be better with the additional cross supports.

looks like it is unanimous! I appreciate everyone's input.