We've already had enough snow this year that our homes may begin to have problems with ice damming. If you have a heavy load of snow on your roof and icicles hanging from your roof, you may be at risk for this issue.
What Are Ice Dams?
Ice dams start with ridges of ice that form when snow on the upper part of your roof melts. Water runs down the roof slope—often under the snow at the eave’s edge—and refreezes at the edge of the roof.
This prevents additional melt from getting to the gutters, so water may leak into your attic, walls and ceilings, ruining insulation, shingles, fascia or soffits, and causing mold and mildew in the walls and attic. Unfortunately, until the water runs through your ceiling, you may not even be aware there is a problem; by the time you notice, you may have major damage to your home.
How to Tell if Ice Dams Are Forming
Any time there is a heavy load of snow on your roof and you see icicles forming on the edge of the roof, look for pooling water near the eaves. Then check for these potential problems that can be caused by that snow melt:
- Stains running down exterior walls just below the eaves
- Rot on exterior walls or in the attic
- Blistering paint on soffits on exterior walls
- Rusty nail heads on the exterior or in the attic
- Matted attic insulation
- Blistered or peeling paint on interior walls
Preventing Ice Dam Problems
The best solution is to keep your roof cold by insulating your home, and also by providing adequate ventilation from your attic and soffits. To prevent warm air in your home from seeping into your attic, add insulation and fill gaps in drywall, cracks around light fixtures, plumbing pipes and other ductwork, chimneys, access hatches, bathroom fans and any other ceiling penetrations. To plug gaps in the attic, rake back insulation and plug leaks using foam or caulk.
Adequate ventilation may also help prevent ice damming, according to some experts, while others say that if minimal heat escapes into the attic, ventilation isn’t critical. If your roof is carrying a heavy load of snow, the ventilation holes may be plugged, so be sure to check them.
Other Recommended Solutions to Prevent Ice Damming
There are a number of options promoted, all of which have caveats for use. But remember these do not solve the real problem—excessive heat loss from your home—and each carries some risk:
- Snow rake. Raking snow off your roof takes a toll on your shingles because they are brittle in the winter, and because getting up on the roof in winter is dangerous, raking is never advised for homes higher than one story.
- Electric heating cables. These are available at home stores, but may or may not be allowed by your building code. They are supposed to keep the roof warm, so that snow doesn’t pile up. The downsides: They can make shingles brittle, water may refreeze in the gutter unless the melted water is routed away, they may be a fire hazard and they take energy to run. They are typically not recommended except as a temporary solution.
- Adhesive ice and water barrier. Adding this self-sealing, waterproof underlayment can only be done when re-roofing (some building codes require it). It is usually attached for 3 to 6 feet up the roof from the gutter and shingles go over the top. The upside: water shouldn’t leak through the barrier. The downside: ice dams may occur higher on the roof’s surface and water may leak into your roof at the higher point.
- Sheet metal ice belts. These are 2-foot wide strips of metal put on top of the shingles at the edge of the roof. However, they are unattractive and won’t stop problems from occurring higher on the roof.
- Hire a roofing company to steam the snow off. This is a big pressure washer; the process is expensive and would have to be repeated every time a load of snow lands on the roof.
A Word of Caution
It’s dangerous to be on the roof when there’s ice and snow cover. There is the risk of personal injury and potential damage to the roof. Also tightening up your home could cause ventilation problems, especially if natural gas or propane comes into your home. Backdraft, exhaust or combustion problems can lead to carbon monoxide poisoning in homes with gas lines.