Ice Damming and prevention at your cottage

An ice dam is an ice build-up on roofs of buildings which may cause water damage to the cottage and contents if the water leaks through the roof.

Ice Damming on your cottage roofAn ice dam is a problem of cottage maintenance on sloping roofs in cold climates. Ice dams on roofs form when accumulated snow on a sloping roof melts and flows down the roof, under the insulating blanket of snow, until it reaches below freezing temperature air, typically at the eaves. When the melt-water reaches the freezing air, ice accumulates, forming a dam, and snow that melts later cannot drain properly through the dam. Ice dams may result in leaks through the roofing material, possibly resulting in damaged ceilings, walls, roof structure and insulation, damage or injury when the ice dam falls off or from attempts to remove ice dams.

The melting of roof snow comes from two reasons: Heat from inadequate roof insulation and heat leaks, and inadequate ventilation. This condition is called a warm roof and the heat conducted through the roof melts snow on those areas of the roof that are above heated living spaces, but the snow does not melt on roof overhangs.

Ice Damming Damage Prevention

Stopping ice dams is simple, in principle: Just keep the entire roof the same temperature as the eaves. You do that by increasing ventilation, adding insulation, and sealing off every possible air leak that might warm the underside of the roof.

Add Ventilation

A ridge vent paired with continuous soffit vents circulates cold air under the entire roof. Both ridge and soffit vents should have the same size openings and provide at least 1 square foot of opening for every 300 square feet of attic floor.

Add Insulation

More insulation on the attic floor keeps the heat where it belongs. To find how much insulation your attic needs, check with your local building department.