Ice dams are harmful to your home’s structural integrity. The fact that they appear as a picture book-pretty fringe of ice around your roof, complete with icicles, shouldn’t take your mind away from the fact. The few structural improvements needed to prevent ice dam formation don’t cost much, and come with benefits that go well beyond ice damage prevention. They are the very definition of a sound investment.
Here’s how ice dams form
The solid fringe of ice around your eaves and in your rain gutters forms when your roof isn’t as cold as its surroundings. When heat from inside your house leaks into the attic, it warms the roof, melts some of the snow on the roof and causes it to trickle into the lowest line of shingles and the rain gutters. As the water freezes, it expands, causing serious damage to both the shingles and the rain gutters. Some of the water will usually also get into the drywall and the attic, and cause rot all around.
Test that attic
If you have living spaces designed into your attic, they should have robust insulation to keep any heat from warming up the roof. Some people even think of putting a boiler up in the attic; needless to say, it’s a very bad idea.
Whatever you use your attic for, you should try putting a thermometer in there close to the roof to see if the temperature is any higher than freezing. If it is, you have a problem, and you need to get better insulation.
Better sealing and insulation
Poor attic insulation can rob your home of a third of its heat. It can be very hard for the DIYer to find and close off every single source of leak. Every gap in the drywall, every opening around a chimney or around plumbing, will need to be sealed off. You will then need to add high quality insulation to top up existing insulation that isn’t doing its job.
If you aren’t using your attic as a living space, you should also ventilate your attic. The more cold air you have passing through the attic, the safer your roof is.
Finally, take a look at those rain gutters
Rain gutters don’t cause ice dams. However, when ice dams do begin to form, they tend to get a great deal of traction building into the rain gutters. When the gutters already contain snow, water trickling down can mix with it to form a solid block of ice.
The answer is to get premium gutters that come covered at the top. Covered gutters hold no snow within, and cannot aid in the formation of ice dams.