In winter, trapped heat can melt snow on the roof, which then refreezes, clogging gutters with ice. Water runoff from the roof gets trapped by the dam and eventually backs up the roof, travels under the shingles, and leaks into the house.
HOW TO DO IT:
"The trick is to keep the top and underside of the roof the same temperature," says Tom Silva. One way to do that in unfinished attics is with a solar roof-vent fan that draws in cold outside air through existing soffit or gable intakes and exhausts warm air that’s built up under the roof. Powered by the sun, the fan, which costs about $300, further saves you money in summer by cooling the attic so your air conditioner doesn't have to work as hard.
You're spared $5,000 to replace rotten roof framing, as well as ceiling and wall damage.