Ice Dams Remain a Risk Even After a Winter Storm Passes
Did you know costly property damage risks remain after severe winter weather conditions have passed? Following significant snowfall, conditions are often optimal for ice dams to form, which can lead to costly water damage.
Ice dams usually form after heat from inside a house or commercial building escapes through the attic causing snow and ice on the roof to melt. Afterward, the water will trickle down to the roofline, where it freezes again when temperatures drop. The ice builds up over time, essentially creating a dam that prevents water from escaping the roof.
The water behind the dam can then seep into the building’s frame and insulation, causing interior water damage. Once this happens, the insulation and plywood inside can become wet, exposing the home or business to a variety of issues such as rotting wood, damaged drywall, and mold growth.
Preventing ice dams is the best way to avoid these kinds of damage issues. Learn how you can avoid ice dams by using the resources below from the Insurance Institute for Business & Home Safety (IBHS). Find additional freezing weather resources at http://www.disastersafety.org/freezing_weather.
REDUCING ICE DAMS
A two-step approach is the most effective way to reduce the size of ice dams. First, keep the attic floor well insulated to minimize the amount of heat from within the house that rises into the attic. Second, keep the attic well ventilated so that the cold air outside can circulate through it and reduce the temperature of the roof system. The colder the attic, the less thawing and refreezing on the roof. These two measures are the best ways to keep ice dams from increasing in size.
Step One: Insulating the attic
The attic floor should be airtight, have sufficient insulation, and keep the transfer of heat from the downstairs to the attic at a minimum. Even a well-insulated attic floor may have a number of openings that can permit warm air from below to seep up into the attic. For instance, these items may cut through the attic floor:
- exhaust pipes and plumbing vents
- fireplace and heating system c hi m n e y s
- light fixtures
Seal all openings around these penetrations, but be careful not to block attic vent s with insulation. The at tic vent s, as explained below, must be kept clear so that they can do their job. Additionally, pull-down stairs or a set of regular stairs leading up to the attic from the lower level can be avenues for rising heat. Weatherstripping around the edges of the attic access door and insulation on the attic side of the door should minimize the passage of heat to the attic. Any heat-generating equipment in the attic should be relocated.
Step Two: Ventilating the attic
There are several ways to ventilate your attic. You can do it with eave vents, soffit vents, a ridge vent, a gable vent, or some combination of these. Most modern residential roofs combine a ridge vent with soffit or eave vents. To the extent that household heat penetrates the attic, it should be able to rise and escape through, for instance, a ridge vent, while soffit or eave vents pull in cold air to replace it. Local building codes generally require a minimum level of ventilation.
Proper ventilation of the attic to let cold in, together with air sealing and insulation on the attic floor to help keep household heat out of the attic, work to minimize the likelihood of ice dams.
REMOVING ICE DAMS
IBHS does not recommend chipping or breaking ice dams due to the damage that can be inflicted on the roof. If you are not physically capable of going onto the roof or are unable to easily reach the roof, consult a roofing professional.
For low slope roofs or flat roofs:
Removing the snow will remove the source of a potential ice dam.
Use a heavy duty push broom with stiff bristles to brush off the snow on low slope or flat roofs.
A shovel or snow blower should not be used because they may damage the roof cover system.
For steep slope roofs:
A roof rake may be used for most single story buildings while remaining on the ground to pull snow down the roof slope.
Do not pull snow back against the slope or sideways since the snow may get underneath the cover and can break shingles.
© 2012 Insurance Institute for Business & Home Safety