Real estate

ASK THE CARPENTER

What to do when bathroom fans and dormers drip

Q. We recently replaced our bathroom fan, and since then when it is cold outside, it drips water onto the bathroom floor. We thought something was wrong with the new fan, so we replaced it. Our handyman went in the attic and insulated around it, thinking that would solve the problem. It did not. It didn’t drip all summer, but now that the nights are cold, it is doing it again. I am afraid the water is building up around the fan and the ceiling will start to decay. Suggestions?

BETSY MASELEK

A. Sounds like a pitch problem. Redirect the exhaust pipe to pitch (or angle) toward the exterior vent hood and not back toward the interior fan. Use solid pipe, seams facing up, and tape all of the seams and elbows. Insulate the pipe with a pipe sleeve. Also, make sure your exterior vent hood closes properly. A visual check from the outside can verify this. TIP: Install a timer switch and run the fan for a minimum of 20 minutes after your shower to clear the room and pipes of moisture.

Advertisement

Q. How would you rate attic fans in un-air-conditioned one-story structures? I see the solar-powered disk-looking rooftop models, the turbine ones, and also attic fans that blow out of the gable vents. I have also seen a system of a ceiling vent piped to the attic gable outlet fan supposedly sucking the air from the interior of the structure through the vent and out. Obviously, these need to have open windows or doors.

Get The Weekender in your inbox:
The Globe's top picks for what to see and do each weekend, in Boston and beyond.
Thank you for signing up! Sign up for more newsletters here

KEITH HERSTEIN

A. Are you trying to cool your house? You could accomplish all of this by simply using box fans in your windows instead of using an attic fan. You would face the fans out in the hottest part of the day and then in to bring in the cooler night air.

I don’t recommend solar-powered vents; they are a disaster and depressurize your attic. They would work year round, sucking air from inside your living area into the attic rather than pulling outside air in from the attic.

Q. I have a Colonial built in 1986. The front of the house has three dormers that are essentially empty spaces in the unfinished but insulated attic. I’ve been in the house for three years now, and each winter there are leaks along the side of the dormers. The roof has a ridge vent, but the dormers are not vented. My theory is that heat is being trapped in the dormers, causing the snow on the roof of each to melt and form ice on the sides. This ice melts and finds its way into the attic. I’m thinking of having ridge vents installed on all three dormers to let the heat out. Is this a good idea?

Advertisement

ERIC

A. Is it possible that you have a void somewhere in the insulation in that area or air leaks? That’s where I would start before adding ridge vents. Air leaks often allow warm air into the dormer. Insulation itself does not stop the air leaks; you need to stop them in order to let the insulation do its job.

TIP: Blackened insulation is always a sign that air is leaking in the area.

Finding air leaks can be tough: Open stud cavities are the worst (located in lowered areas of ceilings like soffits and where the ceiling height shifts, especially in split-level homes). Plug them with a plastic bag partially filled with insulation, and then cover with spray foam. The plastic bag stops the airflow and gives the foam a place to work off of. You can also use tightly fitted rigid foam board or sheet plastic to cover these openings and expanding foam.

Look for floor holes, especially around the outside walls, ducts, recessed lights, or near plumbing pipes and utilities. You can seal these holes by using expanding foam.

Rob Robillard is a general contractor, carpenter, editor of AConcordCarpenter.com, and principal of a carpentry and renovation business. Send your questions to homerepair@globe.com or tweet them to @robertrobillard.