Q Our home is 30 years old, and we have lived in it 10 years. We have had an ongoing problem with water dripping into our living room when below-zero weather is followed by a warmup. Since it doesn't happen during rain and snow melt, we think it's due to condensation. We recently paid a contractor $2,800 to address the problem. He installed additional turtle vents, two turbine vents and a continuous ridge vent. We have water dripping in now. Why? What do we do now?
A Adding the vents was no fix. Indeed, it could have exacerbated the leakage. Here's why:
During frigid weather, rafters and roof underlayment are so cold that any warm air escaping from the living area into the space above the ceiling will condense, freeze and create an accumulation of frost. When weather moderates, the ice and frost thaw and the resulting moisture drips down through insulation and into the house.
Because warm air rises, it's continuously moving up and through these leaks. Adding more vents to the roof only pulls air faster into the cold space, creating more frosting and subsequent leakage as weather mellows. Not all contractors know this, as you now know.
The solution is to cut off the supply of indoor air to the attic spaces. That means closing any leaks. As you look around the room, it may appear solid, but it probably contains some warm-air leaks, such as recessed lights or speakers, light fixtures, electrical outlets, where interior walls join with the attic, etc. You need to identify the leaks and seal them.
You can do it yourself, but you might prefer to hire a contractor to do this. Be sure the insulation contractor will seal these air passes first, then add insulation or ventilation if necessary. If possible, choose a contractor who uses equipment such as an infrared or blower door to first show where the leaks are, and then -- after treatment -- show that they've been sealed. To find contractors, check yellow-page directories under "Insulation contractors" or contact the Minnesota Building Performance Association (www.mbpa.us).
Whether you hire a contractor or do it yourself, it's important to be informed so the job gets done right. Minnesota's Department of Energy Security has information on how to seal leaks at: www.commerce. state.mn.us (search for "air leaks"). To get a publication sent to you, call 651-296-5175 or toll-free at 1-800-657-3710.
Send your questions to Fixit in care of the Star Tribune, 425 Portland Av. S., Minneapolis, MN 55488, or call 612-673-7032, or e-mail fixit@startribune.com. Past columns are available at www.startribune.com/fixit.
