My wife and I bought this house and it is approx 8 years old and we have very noisy floors. When going to put down laminate I was pulling the carpet only to find that where the main hallway wall is(and the most creaking)the entire wall appears to be shimmed with shim-shingles under the bottom plate. I have never seen this and was wondering if this is a correct way to do this. This was a wall that was built when the home was new(not an add-on).
How can I correct this as the noisy floors are driving us crazy?
I plan on screwing the sub-flooring down with good exterior star-drive screws. Is there something else that I need to do?
Plywood or OSB squeaks as the joints rub against each other. Good framing practice is to glue the joints to the joists during construction, and use T&G underlayment. My guess is they did not follow good practice. Your plan sounds fine. Predrill holes in the underlayment larger than the screws shanks. That way the screws will be pulling the underlayment down rather that lifting the underlayment.
Can't explain the shims, either if from original or add on perspective. Framers don't work to fractions of an inch, so shimming would make no sense. It may have been done by the finish carpenters to try and quiet the squeaky floors.
The shims are taking up space. I'd investigate why the space is there.
I would suspect the support under the wall. If this is on the first floor, I would inspect the basement supports. If they were set too low, the floor would have dropped and come to rest on the lowered poles. Why the wall didn't also drop is odd, though.
Post some photos of the support and the gap.