Q. I spoke with you recently about mold in my basement. We have not yet bleached the walls, but did ventilate per your suggestion by opening one of three screened windows (about to pick up new screens for the other two). All went well until we put on the AC the other day in the humid weather. Ducts in the basement condensed so we closed the window. (I forgot to tell you that we have central air.) I had hoped to keep windows open from April to October, but I guess that won’t work. Also, is presence of mildew the same as mold? HELEN, from Westwood
A. Not to worry. Moisture in the basement will always condense on cool metal or cool plastic ductwork. The simple solution is to insulate all ducts in the basement with 1-inch duct insulation (fiberglass covered by a vinyl cover). It is easily done by wrapping the insulation on the duct until the ends meet, and stapling the ends.
Opening those windows did not help much because of the humid weather, nor did they help much when you closed them. Even closed, there is plenty of moisture in the cellar that comes up as water vapor right through the concrete slab. Mold and mildew are essentially the same, and will yield to a 1-3 bleach-water solution.
Q. I put a rubberized mat on the tub floor, and everything was fine until I picked it up. It left a stain which I cannot feel with my fingers, and cannot remove. Also, how can I remove black stains from a rubber material scraping against vinyl siding? MARY CASEY, Westwood
A. For the tub floor, try this: Wet the bottom with hydrogen peroxide, then sprinkle lots of cream of tartar on until it becomes wet with the hydrogen peroxide. Wait overnight, then scrub and rinse. For the rubbery black scuff on vinyl, rub with a rubber cement solvent.
Remember that list of tools?
Last June, Lisa asked in my chat room what basic tools a young woman (or man) should have, to use in a new house. I accommodated her with my version of a list, and sent it along in a column. Now I remember one more: a spirit level, 2 feet long. It’s the only way to keep things level (horizontal) and plumb (vertical). I received other ideas from readers, but stuck to the original list plus one. I thank all for their input.
Q. My floor is scratched a little, so it needs a relatively light sanding. I only have to do the perimeter border, with the rest covered by the rug. How best to do this without removing the finish to the bare wood? ANNE SHEEHAN, Canton
A. Sand the border with medium sandpaper, then again with fine. This will make the floor look horrible, but two or three coats of an oil-based polyurethane varnish will darken it nicely and all blemishes will be gone. If you don’t want to darken the color, use a water-based varnish.
Q. Our neighbor fed the birds, and then pigeons came. We closed off the porch joists, and they gathered on our roof, defacing it. What can we do? BERI & ANTONIA TERRIAN, Newbury
A. A good cure is to cover the roof with needleboards: stainless steel needles that prevent birds from roosting. Two companies make them: Nixalite of America, East Moline, Ill., www.nixalite.com, 888-624-1189, and Ecopic, Birmingham, Mich., www.ecopic.com, 313-647-0505.
Globe Handyman on Call Peter Hotton also appears in the Sunday Real Estate section. He is available 1-6 p.m. Tuesdays to answer questions. Call 617-929-2930. Hotton (firstname.lastname@example.org) also chats online 2-3 p.m. Thursdays. Go to www.boston.com