This guide explains how to protect against problems associated with ice damming, which occurs when a ridge of ice develops on the roof and prevents melt from draining. This article applies to homeowners in regions that experience heavy snowfalls and other weather that is conducive to ice damming. It contains the following sections:

• Causes of Ice Damming
•  Preventive Measures
• Tips and Recommendations

Causes of Ice Damming

Ice damming happens when indoor heat warms parts of your roof surface and melts accumulated snow. As the snow melt runs down the roof, it re-freezes near the edge of the roof (which is still cold) creating an “ice dam.” This cycle of melting and re-freezing snow repeats itself, and the ice dam grows. Eventually, water can work its way under shingles and into your home leading to potential damage or intrusion.

Preventative Measures

Take steps throughout the fall and winter to protect yourself from ice damming.

Early fall. Locate and engage a roofing or snow removal contractor capable of providing rooftop snow removal or “roof raking” services. The contractor should be appropriate for this task, possessing adequate experience, insurance, personnel, and equipment. When talking to them, ask about alternate methods of protection such as heat tapes.

Late fall. After trees are fully defoliated, facilitate inspection and cleaning of all gutters, downspouts, and connections. Leaves, sticks and debris will restrict the flow of water and compound ice damming problems.

Snow events of 6 inches or less. Visually inspect all roof lines for excessive snow build-up, paying special attention to critical areas (such as sidewalls, lower areas of valleys, low pitched roofs, skylights, etc.) Snow build-up should be removed before it hardens, regardless of location on roof.

Snow events of 6–18 inches. A contractor should remove all snow build-up within 6 feet of all roof edges, around skylights, sidewalls, and other critical areas. Ventilation devices such as ridge vents should be cleared to mitigate excessive heat. Snow touching windows, window trim, or soffits should be removed immediately.

Snow events of 18” or more:. A contractor should remove all snow from rooftops if:

• Roof raking has not caused snow on roof to start melting
• Freezing conditions and/or additional snow are forecast

Tips and Recommendations

• If you contract with someone to provide roof raking services, make sure they are up to the task and possess adequate experience, insurance, personnel, and equipment.
• Salt or thawing chemicals should not be used on roofs or in gutters.
• Do not use metal shovels or metal raking equipment on roofs as it could cause damage.
• Snow removed from rooftops should be cleared from any basement window wells, hatchways, outside air conditioning units, heat pumps, etc.
• Snow should also be cleared away to well below the bottom of windows, and away from siding, (especially on decks and patios).
• Certain roof areas may be more prone to ice damming based on their configuration, or their orientation / exposure to the sun. These areas should be identified to most effectively manage the roof raking process.