Question: The stairs going from the first to second floor make a LOT of noise when used. The basement stairs are directly beneath them so I have access to them except that there is sheetrock on the underside of the stairs. The stairs are carpeted as well. What are my options for eliminating the squeaks?
Answer: Over time the nails and/or screws holding the treads loosen. The best fix is to attach 4 to 6 inch triangular shaped pieces to the underside of the treads and risers - use construction adhesive and screws to fasten them.
Additional information on stair tread repair.