Q: What can be done with a tile ceiling that is completely stained from a water leak if I don't want to remove all the tiles and put up new ones?

A: When you say tile ceiling I assume you are referring to conventional acoustical-type ceiling tile. If so, you can paint it with a flat paint. This material is porous, so use latex paint rather than oil or alkyd type, because it won't soak in as much. Using a roller will be easier than using a brush for this job.

Q: The first eight years after my new home was painted the walls looked fine. A good-quality latex semi-gloss has been used. Two years later you could see a 4-inch spot along the joints of the Sheetrock where the panels meet, and where the nails were driven in. Then five years later, on the second floor, I could see a dark imprint on the walls directly in front of the 2-by-4 studs in each wall. Was the wrong kind of paint used; what else could be causing this problem?

A: If you have gotten more than eight years out of the original paint job, you are fortunate these are the only complaints you have. Most of the discoloration is due to accumulations of airborne dust and dirt that tend to settle on wall surfaces over studs, because on an outside wall these areas are slightly colder than the rest of the wall surface (no insulation where the studs are). The same is true where there are nails (metal transmits cold). As a result, slight amounts of condensation accumulate along these places, and this slight extra dampness holds dust and dirt more than the drier nearby surfaces do.

Q: The outside of my house has white aluminum siding and in places this has formed a coating of mold or mildew that cannot be wiped off. Do you have any suggestions about how to remove this?

A: If it is mold or mildew you can wash it off with a solution of one part fresh liquid laundry bleach and three parts water. Add about three handfuls of powdered detergent to a bucket of this mixture, scrub on, let dry on the surface, then flush off with lots of water.