I own a 37 year old bungalow whose floor squeaks all over. Sub-floor is 1/2" plywood. Laminate flooring on top is approximately 1/4" to 5/16" with kraft paper between the floorings. The ceiling in the basement is wide open.
Answer:
With a laminated finished floor about the best you'll do to get rid of the squeaks is to remove the lamainated product and then use 1-1/2" plywood screws to fasten the sub-flooring to the joists. They go every 6 or 8 inches in the field of the plywood and every 3 inches along the butted edges. Now you can either re-cycle the laminated product (if that's possible) or install new. Doing anything from underneath will do nothing to eliminate the squeaks.
