An ice dam is a ridge of ice that forms along the eaves of a roof and prevents the drainage of melting snow. Without proper attention, an ice dam can wreak havoc on a property, causing serious problems that can require costly repairs.
How Ice Dams Form
Ice dams form when heat from the living space of a property rises and warms the upper portions of a snow-covered roof. This heat can melt the snow on the roof and cause it to run down toward the colder eaves and gutters as water. The water then freezes to form a ridge of ice, which prevents the drainage of melting snow.
Why Ice Dams Are Dangerous
An ice dam can loosen roof shingles, dislodge gutters and cause water to back up and leak into a property. Water ingress can damage a property’s walls, ceilings, insulation and roof structure, and the resulting dampness can cause health issues for a property’s occupants. Attempts to remove an ice dam can also cause damage to people and property.
Tips on How to Prevent Ice Dams
Preventing ice dams is easier than fixing the damage they can cause. Following are four strategies for how to prevent ice dams.
1. Design for Snow Loads
Poor roof designs are a major cause of ice dam formation. Complying with the American Society of Civil Engineers‘ standards for “Minimum Design Loads for Buildings and Other Structures” is the best way to ensure that roofs can withstand snow loads.
2. Increase Roof Insulation
Adding additional roof insulation helps prevent heat from the living space escaping through the roof. Adequate roof insulation extends to the exterior wall line of a property and doesn’t restrict roof ventilation.
3. Improve Roof Ventilation
Ventilation helps keep the roof deck evenly cool by providing the underside of a roof with a continuous flow of cold air. A properly designed roof ventilation system has both intake vents in the soffits and exhaust vents at or near the ridge. If older construction does not permit soffit and ridge ventilation, powered fans can be a good alternative.
4. Place Gutters Correctly
Gutters protect a property from water damage, and proper placement is key to avoiding costly repairs. Installing gutters under the drip edge flashing helps prevent ice from forming at the roof edges.