Claims are no fun.
Vermont Mutual Insurance Company released a helpful advisory to help Massachusetts homeowners Protect Your Property From Ice Dam Water Damage:
One of the most common and repetitive causes of property damage to building interiors is water damage resulting from the formation of ice dams on roofs. An ice dam is a ridge of ice that forms at the edge of a roof and prevents the water produced by melting snow from draining off the roof. The water that backs up behind the dam can leak into a home causing damage to walls, ceilings, and insulation.
While ice dams can develop as a result of multiple factors, the most fundamental causes are:
- Heat leakage from the interior of the building into attic or loft areas that warms the middle and upper areas of roof decks (see causes of heat leakage below).
- Snow accumulation on the roof surface which provides the potential for snow melt and re-freezing in the form of an ice dam. This problem can be amplified by lower pitched roofs.
- Sustained exterior temperatures below 32 degrees which creates conditions under which snow melt water will re-freeze at the eave level of the roof.
Heat leakage can result from any number of factors common to residential properties:
- An insufficient layer of insulation in the ceiling assembly below the attic or loft area as well as uninsulated or poorly insulated exterior walls.
- Impoperly insultated recessed ceiling lighting fixtures.
- Improperly sealed and insulated ventilation fans, heating and air conditioning ducts and plumbing vent stacks.
Strategies for avoiding water damage from ice dams take two forms; those that are intended to prevent the formation of ice dams and those that are designed to provide a reliable means for roof surface snow melt water to drain off the roof to prevent water accumulation behind the ice dam.
Prevent the Formation of Ice Dams
- Provide soffit and ridge ventilation to create and sustain a flow of cold air along the bottom surface of the roof deck.
- Increase the thickness of insulation in the ceiiling assembly below the attic or loft area.