Q Our house is only five years old, but some of the door frames are rotting. What can we do about this? -- W. Smith

ASome wood will rot in only a few years if it is frequently exposed to moisture and is not well protected with a wood preservative or paint. This is especially true of wood that is exposed to puddled water, such as at the bottoms of door frames, porch columns and the like.

Rotted wood can be patched, but it is better to replace the rotted piece if possible, especially if the wood supports weight (such as a porch post or deck post).

If you prefer to patch the wood, there are several special products. These are generally two-part epoxies that are mixed immediately before use. Examples are High Performance Wood Filler by Minwax (www.minwax.com) and WoodEpox by Abatron (www.abatron.com). Auto-body filler such as Bondo, which is sold at many auto-parts stores, can also be used. When mixed, these products have a putty-like consistency and are applied with a putty knife or similar tool. When they harden, the patches can be smoothed with a file, sandpaper or other woodworking tools. The finished patches are painted just like wood.

Most rot-repair products have a strong odor. It is best to mix and use them outdoors or in a well-ventilated area. Be sure to read the directions and cautions before using. Cut out or otherwise remove as much of the rotted wood as possible before attempting to make a patch.

Sometimes the wood surrounding an area to be patched needs to be strengthened before the patch is applied. Liquid "hardeners" are used for this purpose. Minwax's version is High Performance Wood Hardener and Abatron's is LiquidWood.

In a recent column, you mentioned that zinc strips can be used to help prevent mold from forming on roof shingles. There are many houses in my area with this problem. How are the zinc strips installed? Is more than one strip needed? -- L. Hickin

The strips are simple to install if you feel comfortable and safe working on a roof. If not, it is best to hire a roofer.

The roof must first be cleaned of any existing mold with a roof cleaner such as Shingle Shield. The zinc strips come in sections about three feet long. On most sloped roofs, a single line of strips is installed on each side of the roof close to the ridge. The strips have flanges that are nailed under the tabs of the shingles so that nail heads are concealed but a strip of zinc is exposed. Rain water washing over the exposed zinc causes a chemical reaction that inhibits the growth of mold.

For more information on zinc strips and their installation, check the Web site www.shingleshield.com.

We live in a two-story townhouse, and when the downstairs plumbing is used the pipes make horrible banging noises. A plumber said that it sounds like a bad washer somewhere and that it would take a while to locate it. Any suggestions? -- Barbara

A loose or worn faucet washer is sometimes the cause of plumbing-pipe noise, but if this is the cause, it shouldn't be hard to locate. For one thing, most modern homes have few washer-type faucets; they have been replaced by washerless faucets.

There are several other possible causes of pipe noise. If the noise occurs when a faucet is turned off, it is probably "water hammer," caused by a lack of air in the pipes. Eliminating this type of noise might require installing air chambers on some of your fixtures.

Hard-water deposits in the pipes might also make it difficult for water to flow properly, which can cause vibrations and noise in the pipes. This problem usually occurs in areas where hard water is prevalent. The pipes can sometimes be cleaned chemically.

Some pipes might simply be loose, causing them to knock against wood framing when water runs through them. Check exposed pipes to see if this is happening, and fasten any loose pipes securely. If loose pipes run through walls, there is little you can do short of major reconstruction.

Questions and comments should be sent to Gene Austin, 1730 Blue Bell Pike, Blue Bell, Pa. 19422. Send e-mail to doit861@aol.com. Questions cannot be answered personally.