I recently got a letter from Jason Nemoy. He and his wife are first-time homebuyers who bought a new home in Baltimore in October.

They had a home inspection, and the items that were noted are being slowly being fixed by the builder during their one-year warranty period. But they feel that one thing was overlooked: a pinging/knocking sound in some of the plumbing in the house.

Mr. Nemoy stated that he has made the builder aware of the problem but that the builder's reply was that "it's normal and it won't cause any problems." Mr. Nemoy wants to know whether the problem can become worse and cause serious water damage. He also wants to know whether he should contact the previous home inspector and have him reinspect.

Noisy pipes can be annoying, particularly in a new house. As with squeaky floors, the cause of the noises is usually poor workmanship. The recurring noises serve as a constant reminder of doubts about the workmanship.

Pipes that make tapping or pinging noises are usually hot-water pipes. Hot water rushing through them causes thermal expansion, causing the pipes to move a little.

The movement isn't supposed to make noise, but excessive friction between the pipe and an adjoining object, such as a floor joist, can cause the pipe to grab and release in a staccato fashion.

This excessive friction is often a result of overly tight pipe straps that don't allow for expansion and contraction. Another cause could be pipes that are sagging because of an insufficient number of pipe straps holding them in place.

Fixing the noisy pipes is easy if you can get to them.

Overly tight clamps can be replaced with clamps that allow movement without making noises, and additional clamps can be added where that is needed. However, if the pipes are concealed in the walls or ceiling, it will be necessary to cut through the walls or ceilings to make the repairs, followed by patching and refinishing. Thus, the builder's resistance to making the repair.

As for the long-term significance of the problem, it is possible that the friction causing the noise will ultimately damage a pipe, for example if the pipe is scraping against a harder material, such as a nail, which gradually gouges the pipe.

It's not very likely, but even so, even if the problem isn't likely to cause greater damage in the future, the noise is bothersome to you, it was preventable during construction, and it can be repaired, so maybe you should stick by your guns.

Decide first, however, whether you're willing to tolerate the dust and inconvenience of the drywall refinishing and repainting that might be necessary as part of the repair.