Handyman on Call

Why is he getting condensation around air conditioning vents?

Boston Globe Handyman Peter Hotton is not writing today. This column originally ran on June 22, 2008.

Q. I am getting a lot of condensation around two of the air conditioning vents coming out of my cathedral ceiling. No other vents in the house do this. It is enough to wet the plasterboard around the vent, causing it to decay. What is wrong and how can I fix it? The air conditioning man said the duct is not laying flat and after that we caulked, but the problem continues.

SLIDELL, Louisiana

A. Air conditioners are not supposed to do that, because they are dehumidifiers as well as coolers. I think what is happening is that both the ducts coming out of the cathedral ceiling as well as the ceiling are not insulated, and the cool air coming out of the vents condenses just as it comes out of the ducts. Insulate the space between the ceiling and roof, being careful to ventilate the space above the insulation. And, insulate the ducts, or install pre-insulated ducts.


Q. How can I clean plastic lawn chairs, especially of bird waste?

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A. Count the ways: a strong detergent and water solution, plus a cup of bleach, left for a minute or two on the chair, scrub, and rinse. Rub with Mr. Clean Magic Eraser.

Q. Can gutters be adjusted up or down to make them drain better? I am getting a few shallow puddles in some sections of my gutters. If those puddles are allowed to remain, would they become a place for mosquitoes to breed?

S.D. , East Greenbush, N.Y.

A. The only way to adjust the gutters is to take them down and put them up again, something I would not encourage. The gutters are probably close to level, and a level gutter will indeed drain. The puddles are probably too shallow and will evaporate quickly enough to prevent mosquitoes from breeding. If you are that concerned, put Mosquito Dunks granules in the puddles to prevent breeding. The only other thing to do is to slope the gutters 1/16th of an inch, per foot. But I don’t think it is necessary.


Q. I have a flock of sparrows — I swear it is a flock — in a third-floor bathroom vent that exhausts through a wall. It has been six weeks now, and I am sure the babies have gone, but the remaining birds are driving me nuts. How can I push them out and put a proper closure for the vent?


A. Use a long-handled brush to push them out. A proper outside closure will prevent anything from coming in. Two brands of ducts and covers are Vent-Axia and NuTone.

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 on house repair. Call 617-929-2930. Hotton ( also chats online about house matters 2-3 p.m. Thursdays. Go to