Q: I am finishing my basement for living space. I have applied two coats of a waterproofing paint to the walls and have not detected any moisture for two years. I plan to use fiberglass insulation and wood framing. Do I need a vapor barrier between the wall and fiberglass?

--P. Knight

A: If you are satisfied that there is no leakage or seepage through the walls, you should not need a vapor barrier on the wall side. However, if your house is heated in winter, you should use a vapor barrier on the inside of the insulation to prevent moisture penetration. You can either use kraft-faced fiberglass, stapling the paper flanges to the inside of the wood studs, or you can use a vapor-barrier primer, such as Zinsser's shellac-based B-I-N, on the inside of the drywall that should cover the insulation.

A couple of other things to keep in mind: Be sure to carefully insulate the band joist around the top perimeter of the basement walls. You can cut chunks of fiberglass and stuff them into the joist cavities. Also, you might consider other options for insulating the walls. For example, Owens-Corning, a leading manufacturer of fiberglass, makes other products that could be used, including rigid foam insulation and a basement finishing system that eliminates framing, drywall and painting.

My roof shingles have dark stains from a fungus. I had a roofer look at them and he advised me to buy zinc tape and put it on the roof. Is the tape difficult to install? Also, will roof cleaner damage the shingles?

-- Jessica

Zinc strips to help prevent roof fungus are generally sold in two forms: rolls of flexible material and short, rigid strips. Both require getting on the roof at its highest point (the ridge) and fastening the zinc strip there. Also, existing stains must be removed before the zinc, which reacts chemically with rain water, will do much good.

Z-Stop (www.z-stop.com), is an example of roll-type zinc. It comes in a 50-foot rolls costing about $55 and is attached at the roof ridge with special nails with neoprene washers that are supposed to prevent leaks. Shingle Shield (www.shingleshield.com, about $70 for 48 feet) comes in three-foot strips and has a flange that is nailed under the shingles.

Shingle Shield also offers a cleaner that is applied with a garden-type sprayer and washed off with a forceful spray of water.

Roof cleaners contain powerful chemicals, and I can't assure you that they won't damage your shingles. However, the cleaners are widely used and they are rinsed off soon after application, so there doesn't appear to be much risk.

Unless you feel you can work high on a roof safely, I think the entire job should be done by an experienced roofer.

We moved into a home with a glass shower stall. The glass is etched with hard-water stains, and I have tried everything to remove them -- store cleaners, homemade cleaners, elbow grease. What's next? --L. Doyle

If all else fails, try scraping off the mineral accumulation with a single-edge razor blade (or make it a little easier and buy a razor-blade scraper with handle at a paint store). Several readers have told me this laborious method worked for them. Once you get the glass clean, keep it that way by periodically giving it a light coat of automotive wax. Use a squeegee to remove water from the glass surface after every shower.

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.