Green Newton

Ice dams in Massachusetts are an ongoing nuisance and cause extensive water damage to homes and structures.  Recent record-breaking winters throughout the country have caused damage to tens of thousands of homes as a result of ice damming.         

What is it and how does it work:

An ice dam occurs when snow accumulates on the slanted roof of a house with inadequate insulation. Heat conducted through the insufficient insulation and warm air from the attic bypasses warms the roof and melts the snow on those areas of the roof that are above living spaces, but does not melt the snow on roof overhangs.  Melt water flows down the roof, under the blanket of snow, onto the eave and into the gutter, where colder conditions on the overhang cause it to freeze. Eventually, ice accumulates along the eave and in the gutter. Snow that melts later cannot drain properly through the ice on the eave and in the gutter, resulting in leaks to the roof space resulting in damaged ceilings, walls, roof structure and insulation.

Primary Prevention Measures:

• Insulation – Installing additional insulation on the attic floor will reduce the temperature in the attic. Keep in mind once you reach the area’s optimal R-Value (a measure of the insulating value of a material), a further increase in the amount of insulation will not show an appreciable decrease in heat loss.
• Weather stripping – And/or insulation can also be installed on attic stairways or hatchways and on attic floor-mounted louvers for whole house ventilation fans. Review manufacturer specifications on the fans or recessed lighting fixtures if the additional insulation will adversely affect their performance.
• Ventilation – Without an adequate amount of ventilation, heat will build up despite the amount of insulation.  Ventilation will also remove water vapor that can condense in the attic and result in dry rot and rust.  If the house roof has an overhang, or soffit, vents can be added to these soffit areas. A ridge vent can also be added. This vent is mounted along the length of the peak of the roof. The cold outside air that enters the soffit vents rises along the inside of the roof and exits through the ridge vent. This action cools the roof and removes moisture at the same time.