Snow accumulation can be a hazard on a roof. Not only can it slide off and injure someone below, but it may also put too much of a weight load on the roof and cause structural damage. There are a few options for minimizing snow load on a roof.
1. Use a Weathershield
A weather shield is a special underlayment membrane that is installed beneath the shingles. It provides additional protection against moisture, particularly along the drip edges where snow accumulation can lead to ice dam formation and attic leaks. Weathershield is only an option when you are having a roof re-shingled, as it can't be installed on an existing roof.
2. Remove Obstructions
Obstructions on the roof can prevent snow from sliding off as it normally would on a sunny day, which leads to accumulation and an increased chance of leaks or weight load issues. Any horizontal edges that are perpendicular to the roof slope, such as the upper edges of a skylight, can act as an obstruction. Some devices can be installed at an angle above these obstructions that route the flow of snowmelt around the obstruction so the moisture doesn't get stuck on the roof.
3. Choose the Right Material
Certain materials are better at shedding snow than others. Metal roofing panels shed snow easily, whether the roof has a steep slope or is low sloped. The smoothness of the material combined with no horizontal seams to catch the snow, along with how easy metal heats on a warm day, means snow rarely builds up. Just take care, as the sliding snow can be quite heavy so you don't want it to dump on porches or driveways.
4. Improve Attic Insulation
Pour attic ventilation encourages the formation of ice dams and it can lead to increased snow accumulation. A vented attic has a constant flow of air that comes in through the eaves and moves up and out through ridge vents. Without this airflow, hot air accumulates in the attic, which causes the lower part of the roof snow accumulation to melt and seep beneath the shingles while the upper layers of snow stay frozen. Proper venting solves the problem.
5. Install Heat Cables
For severe accumulation or accumulation in areas where falling roof snow could pose a hazard, such as above a doorway, heat cables installed upon the roof are the answer. These cables are triggered by low temperatures, so they only come on as needed. They provide a low heat -- just enough to melt the snow but not hot enough to pose a fire hazard.
Contact a roofing contractor in your area if you need more help with winter snow on your roof.