Do-it-yourself Q&A By Gene Austin Friday, February 11, 2011; 1:11 PM Q. The bathroom grout in our 14-year-old house has become stained, and we haven't been able to clean it with various products, including bleach. How do we restore the color? -D. Lilly A. Bathroom grout can pick up several difficult-to-remove types of stain, including minerals from hard water, soap scum, mildew and mold. Grout cleaners generally help, but the method of cleaning is often as important as the cleaner. It often helps to spray on the cleaner, let it work for several minutes, then scrub with a soft brush. Regular household cleaners such as Mr. Clean or Simple Green sometimes work well. Some home owners swear by oxygen-type bleach, not chlorine bleach. Others prefer special tile cleaners such as Tilex or Kaboom. When just cleaning doesn't work, a good option is to dye the grout, restoring either its original color or picking a new color. You can find grout dyes at some ceramic-tile dealers, and the Internet has many sources. One source, groutrevive.com, offers a grout-coloring kit ($43) that includes a pre-treatment, colorant, applicator brush, gloves and other materials. Available colors include white, black and several shades of gray. Cleaned or newly colored grout will stay that way longer, and be easier to clean, if the grout is coated with a sealer. Grout sealers are available from tile dealers or on the Internet. Q. Our builder used polystyrene foam panels to insulate the ceiling over the crawl space below our kitchen addition. The floor still gets quite cold. If I remove the foam and staple high-R batt insulation between the joists, would it help? -A. Francese A. It depends on the thickness and type of the polystyrene insulation used, but there is a good chance you can improve the insulation in the crawl-space ceiling. Polystyrene panels have insulating values ranging from about R-3.5 to about R-5 per inch of thickness. Panels two inches thick would give an R value of no more than about 10, which isn't enough for floors in even warm-climate regions, where R values of R-13 to R-19 are recommended for retrofitting floors in existing homes. In cold climates, R values of 25 to 30 are recommended. You can achieve high R values with fiberglass insulation tucked between the joists of the crawl-space ceiling, although you might be limited in the thickness of your insulation by the depth of the joists. Fiberglass insulation can be held in place with lengths of stiff wire jammed between the joists under the insulation; the wires are sold by insulation dealers. You don't mention the floor of your crawl space, but it should be covered with a layer of thick plastic sheeting to help keep moisture from migrating into the crawl space. Hold the plastic in place with bricks or stones. Q. I cleaned my vinyl siding with a mixture of three quarts of warm water, one quart of chlorine bleach and one cup of TSP. It did a great job on the siding but left white stains like water drops on the window glass. Windex didn't remove the spots. Can you help? -Tom A. I think that cleaning solution was too heavy on the bleach and TSP (trisodium phosphate). TSP is a very powerful cleaner, and that much bleach shouldn't be needed even if the siding has some mildew stains. A cup of bleach and a quarter-cup of TSP in a gallon of warm water might have been better. A soft brush is the best applicator, but it sounds like you used a sprayer of some sort. In any case, it is a good idea to protect windows by taping plastic sheeting to the frames. You should also rinse the surface with clear water as soon as possible. It is possible that the glass has been etched by the mixture, but you can try this cleaning method. Test it first on a few spots in the corner of one of the window panes. Get some very fine (4-0) steel wool and soak it in Windex. Rub the stains gently at first to make sure you are not scratching the glass. If the stains soften and come off, rinse the test area and check again for scratching. If all is well, proceed with the remaining stains. If Windex doesn't work, try the steel wool and a couple of other solutions - a quarter-cup of ammonia in a quart of warm water or a 50-50 mixture of white vinegar and water. Caution: Don't try mixing ammonia and bleach; it generates a dangerous gas.