Ice dams are ridges of ice that form at the edge of a roof and prevent melting snow (water) from draining off your roof. The water that backs up behind this “dam” can leak into your business and cause damage to walls, ceilings, insulation, and other areas. Additionally, when the roof doesn’t drain properly, snow, ice, and water remains trapped on the roof, adding loads that put your roof at greater risk.
Preventing Ice Dams
IBHS offers the following guidance to help prevent damage from ice dams:
- Increase insulation above ceilings.
- Create a roof preventative maintenance, including periodic roof drainage inspections.
- Install self-regulating heating cables on gutters, downspouts, and around roof drains.
- Keep all drains, scuppers, gutters, and downspouts free of debris and vegetation.
- Prune trees that may hang over the roof to prevent an accumulation of tree leaves and branches that may clog or slow roof drainage.
- Improve ventilation. Consider installing electric power vents with thermostats.
Removing Ice Dams
IBHS does not recommend chipping or breaking ice dams because this can damage the roof. The following IBHS guidance is for the most common types of commercial roof systems.
Steep Sloped Roof Systems:
- If the building has a history of ice dams, remove the snow to reduce the risk.
- If the building is too tall to reach with a roof rake from the ground, hire a roofing professional. For more information, please see Selecting a Roofing Professional.
- Remove or relocate heat sources that are installed in open areas directly under the roof.
- Increase ventilation in attic spaces:
- New gable roofs: Soffit/ridge vents provide good ventilation.
- Gable end vents: place an electric fan over vents to increase the flow of air.
- Hip roofs: Box or static vents are practical improvements.
- Insulate recessed light fixtures in the ceiling to reduce heat entering the attic. Look for visible light inside the attic. If present, insulate or seal.
- Insulate or seal all attic penetrations: partition walls, vents, plumbing stacks, electric and mechanical chases and access doors.
- New roof installation: Seal the roof deck using at least two layers of underlayment cemented together or a selfadhering polymer modified bitumen sheet. Extend the moisture barrier at least 24 inches from the edge of the eaves to beyond the inside of the exterior wall.
Flat, Monoslope and Low Sloped Roof Systems:
- Flat roofs are particularly vulnerable to water leaks if ice dams keep water from flowing into roof drains. Removing the snow will remove the source of a potential ice dam.
- If ice dams form around drains, place heating cables on the roof and connect the cables to the drains to create a path for the melting ice to follow.
- Consider installing heating cables in a zigzag manner inside gutters.
- If there is extensive ice build-up around the drains, consult a roofing professional.
- When the roof is dry, inspect the roof cover. Look for mold, mildew and vegetation, all of which are signs of a problem with the slope of the roof cover system and drainage. A roofing professional can advise you about re-pitching the roof cover.