Q. When I bought a 30-year-old house six months ago, the walls were in bad shape. Two coats of primer and two coats of paint made them look good. But near one window, holes formed about 2 inches from the casing, the diameter of a brad, and plaster's coming out of the holes like a vertical ant hill. How can I fix this?
I'm stumped. That little pile of gypsum may indicate insects, such as ants, powder post beetles or house borers.
Another thought: Moisture is condensing on the back of that plasterboard wall, and the gypsum inside the plasterboard's paper skin is deteriorating.
Try this: Enlarge the holes just a little and fill them with joint compound, smooth off, let dry, and sand smooth. Touch up with the primer and paint. This is a shot in the dark. If it occurs again, I suggest cutting a larger hole to see what is going on in that cavity. If there is a hornet's nest or beehive, you'd hear them.
Q. One estimator for my new roof of architectural shingles proposed to put up an 8-inch drip edge, with a 6-foot-wide Ice & Water Shield along all edges of the roof. Is this good as a roof? Also, he said he cannot weave architectural shingles across valleys because the shingles are too thick. He proposed cutting the shingles where they meet in a valley, creating a single seam in the valley.
That would work. The most important part of those valley shingles is the underlayment beneath them. Generally, flashing is made of two layers of roll roofing, the first 18 inches wide, the second 36 inches wide.
Do not fold the roll roofing into the valley; let it gently span the valley. Metal flashing can be used instead, and it can be folded. Contemporary roofers may use a different material for flashing.
Q. I have a big old house with a big old cast-iron vent pipe, the so-called soil pipe that goes from the cellar up through the attic and to the outside. Being of such mass, it stays quite cold, cold enough for water vapor to condense, and in the bathroom, where it is boxed in, the water has dampened the walls around the box, and caused paint to peel and bubble near the box. It is also affecting the tiles, which seem to be spreading. How can I prevent that condensation? I cannot get to the pipe in the attic because it is surrounded by a room.
It sounds unlikely, but it is so. Water vapor is condensing on the pipe and the water is soaking the plaster or plasterboard from inside, causing the paint to peel and the tiles to wander. Any damp plasterboard must be removed, but the real solution is to insulate that pipe. I insulated my big soil pipe by pouring vermiculite insulation down an opening; after 100,000 coffee cans of insulation it finally filled up. You can do that, but it would be better to take off a section of that box, and insulate the pipe with 3-inch fiberglass insulation, or if that is too thick, 1- or 2-inch duct insulation, which has a gray vinyl skin and makes it easy to install it snugly and completely.
Q. I have two Kohler toilets in my house, which is 35 years old. My water is from an artesian well, and it is very hard. The outlet in the tank, where water flushes, is heavily corroded by a mineral buildup, so the flapper ball does not seat correctly, and the toilet leaks a little. How can I clean off that mineral buildup?
Drain the tank and rub the buildup with an emery cloth, a waterproof abrasive cloth. There are other products that will dissolve the mineral: Zud, Lime-Away, CLR (Calcium, Lime, Rust), and a hydrochloric acid-based bowl cleaner.
Peter Hotton: The Boston Globe, 135 Morrissey Blvd., Boston, MA 02107;
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