How to seal odd holes in walls

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?

ROBERT CLOUD, Gadsden, Ala.

A. The handyman is stumped. That little pile of gypsum may indicate an insect, 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. Then touch up with the primer and paint. This is a shot in the dark. If it occurs again, I suggest cutting a larger hole in the plasterboard to see what is going on in that cavity. If there is a hornet's nest or beehive, you'd hear them. Anyone "out there" have ideas? The handyman, and Robert Cloud, would like to know.

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.

SERIOUS ABOUT ROOFS

A. 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.

Globe Handyman on Call Peter Hotton also appears in the Sunday Homes Section. He's available 1-6 p.m. Tuesdays to answer questions on house repair. Call 617-929-2930. Hotton's e-mail is photton@globe.com