Squeaky floors are very common in older homes. Wood floors squeak when something--usually a board--works loose and rubs against another board or against the subfloor. You can de-squeak the floor by either lubricating between surfaces that rub to reduce the friction, or by stopping the movement altogether.

Lubricating is easy but not always effective. First, try working a little powdered or liquid graphite or talcum powder between floor boards. Then clean up the surface.

Stopping the movement is usually a more permanent solution. To determine exactly what is squeaking, go under the floor if possible, to a basement (without a finished ceiling) or crawl space, and listen while somebody walks above you. If necessary, remove any insulation.

* Check for nails that have missed the floor joists and are rubbing up against the joists, causing the squeak. If you find these types of nails, cut them off with a good pair of diagonal cutters.

* Also check for areas where the subfloor may not be nailed down with enough nails. If there is a gap between a joist and the subflooring, drive a glue-coated shingle or shim between the joist and subfloor--just tight enough to kill the squeak. If that doesn't work, drive a screw through the subfloor into the underside of the surface flooring. Be sure the screw is short enough not to pop through the surface; insert it through a fender washer before driving it. It's easiest to use square- drive or drywall screws and a power screwdriver or cordless drill with the appropriate driver tip.

* Nailing solid blocking between floor joists can also strengthen the support for subflooring, eliminating squeaks. If the joist is sagging and the subfloor is flat, cut a piece off of a 2-by-4 to extend 12 inches beyond the gap on either side. Nail it to one side of the joist.

* Squeaks coming from between joists may be caused by inadequate bridging. Renail any loose planks and, if necessary, install a reinforcing piece of bridging against the subfloor.

* Finish flooring that does not fit flush with the subfloor can be tightened from below. Drill a couple of 1/4-inch holes through the subfloor but not through the finish flooring. Press the nozzle of a carpenter's glue bottle into the holes and force glue up into the space between subfloor and finish flooring. Then have someone stand on the raised spot while you drive screws through the subfloor into the finish floor. Be sure the screws are long enough to grip the finish floor without going all the way through, and use washers to ensure the screws will not be pulled into the subfloor. Another method is to pre-drill pieces of 2 by 2, 18 inches long, at convenient angles for driving 2-inch or 2 1/2-inch screws into the subfloor and joists. Partially drive the screws into the pre-drilled holes. Coat the screws with yellow carpenter's glue and power-drive them into place.

* If you can't get under the floor, or the underside is covered with a finished ceiling, try squirting wood glue into cracks between boards and working it in with a putty knife. Wipe up the excess glue and weight down the surface. As a last resort, drive ring-shank nails at a slight angle into floor joists. Drill pilot holes first so that the wood does not split. Fill any visible holes above the nails with wood putty or wood plugs made for the job.

* If your flooring is covered by carpeting and you don't have access from below, drive trim screws (they have very small heads) through the carpet, padding, and subfloor into joists (you can stick a bent coat hanger through a small hole to locate them). The most effective way to do this is to drive them into joists at an angle from both sides (in a V-shaped formation). Predrill screw holes through the subfloor and make a small incision in the carpet so you don't wind its fibers onto the drill bit. If this doesn't work and the squeaks are too bothersome, you may have to pull back the carpet and screw down the subfloor. Call a carpet installer to handle reinstallation.

If none of these methods works, there is always one last resort: earplugs.

More about Wood Floor Repairs:

• Common Wood Floor Problems and Repairs
• Cleaning Dark or Dirty Wood Floors
• Recoating a Polyurethane Wood Floor Finish
• Removing Wood Floor Scratches & Dents
• Repairing a Stained Floor
• Replacing Damaged or Rotted Wood Flooring