Q: The stairs on our main staircase squeak loudly. We can't secure them from underneath because a plaster ceiling covers the bottom of the staircase. How can we stop this annoying squeaking?
A: The problem is likely right on top, where the tread (the flat part you step on) is attached to the stringers (the staircase's framing). The cause for the squeak is simple: When wood ages, it dries out. This makes it shrink, and the fasteners, probably nails, have room to move up and down as weight is applied. That causes the loud screeching noise. The solution is to refasten the tread to the stringer. Use screws; for extra holding power, squirt an adhesive such as Liquid Nails along the screw first. To avoid noticeable screws on uncarpeted stairs, countersink the screws and then fill the holes with putty. If the stairs are carpeted, remove the carpet first.