QWhen we moved into our neighborhood, we noticed black stains on the roofs of some of the houses. Now we are getting the same type of black stains on our roof. What is this and how do we get rid of it? -- T. Coleman

AThe black stains are mold, probably mildew, and they are prevalent on asphalt-shingled roofs, especially in humid areas. Cleaners are available to remove the stains and you can do it yourself if you feel comfortable working on a roof and follow good safety precautions. One cleaner that seems to work well is Shingle Shield Roof and Deck Cleaner (www.shingleshield.com). This cleaner is usually applied with a garden-type sprayer and is rinsed off with a hose.

After the shingles are clean, zinc strips can be installed on the roof to help keep the stains from forming again. Rain washing over the zinc causes a chemical reaction that retards the growth of the mold.

We recently cleaned our deck and applied a coat of stain-sealer. Some of the stain got on our vinyl siding. How can we clean up the siding? -- B. Clark

Several brands of deck-stain removers are sold at home centers and paint stores, and any one could solve your problem. One possibility is Flood's StainStrip (www.floodco.com), which will remove all types of deck stains and sealers. I tested this product on vinyl siding and could detect no damage. However, you should test any product first on a small area of your siding.

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.