We have a 26 year old Burnstead house in the Pacific Northwest. The floors were a bit squeaky when we bought the house 5 years ago. The squeaking has increased quite bit in the years since we bought the house. Pretty much the entire second floor has squeaks. We are hoping to fix the squeaky subfloors when we pull out the the old carpet, before putting in a new carpet. The solution advised on the Internet seems to be putting in screws about 12 inches apart to properly fasten the subfloor boards to the joists. Does that sound like the right and complete solution? - Should the screws be closer together than being 12 inch apart? - Should we be using any other material in addition to the screws, for example, injecting liquid nails / glue? I am not sure if glue was used when the subfloors were originally installed. - Subfloor appear to be 1/2 or 3/4 inches thick plywood. Should I consider adding another layer of subfloor to make sturdier while screwing it down? - Will the squeaks go away after using screws or will they eventually come back - how soon?