Ice Dam Prevention and Removal Solutions for Your Roof
Winter weather brings with it a lot of the things we love here in Minnesota—winter sports, cozy fires, warm beverages, and the beauty of a snow-covered landscape. But the cold temperatures and snowfall also usher in something much less enjoyable: ice dam season. Whether you own a home or commercial building, it’s important to know what ice dam removal options are available to you if they occur, as well as what can be done to prevent ice dams from forming.
What Causes Ice Dams?
Ice dams form when roof ice melts and reforms on the eaves and valleys of your roof. As heat escapes from below the ceiling into the attic, it warms the roof deck. As the roof deck warms, it melts the snow on your roof, and the water travels down the roof until it reaches the eaves, which do not receive as much of the escaping heat. When it hits this colder part of the roof, the water refreezes and forms ice. This ice builds up along the roofline, keeping gutters from carrying water away from the house and causing melted snow to build up behind the ice dam.
Over time, this water can creep up under the shingles, and in cases where the home has a compromised moisture barrier, water can penetrate the building’s envelope and cause interior water damage.
What Damage Can Ice Dams Cause?
The water damage caused by ice dams can result in:
- Rotting wood, including on roof decking, framing, sheathing, and rafters.
- Mold growth: Water that has entered a building’s envelope often goes unnoticed for a long period of time. During this time, the gathering moisture can cause mold growth.
- Icicle formation: Continuous snowmelt against the roof can cause the formation of icicles on the eaves of the building. These icicles eventually break off, often taking shingles or part of the gutter with them.
- Ineffective roof insulation: As water penetrates the roof, it can saturate the insulation, compressing it and dramatically reducing its effectiveness. This in turn increases the possibility of heat loss through the roof and the likelihood of future ice dams forming.
Removing Ice Dams
Ice dams can be removed by a properly trained professional using an ice dam steamer. This commercial steaming equipment heats water and dispenses it under low pressure. A roofing professional will first remove excess snow from the roof with a shovel or rake, then will use the ice dam steamer to steam channels through the ice to help it melt. They will also chip away at parts of the dam as they go, working until the roof is completely clear of ice. Once the ice dams are removed, your roofing professional will recommend options for preventing ice dams from forming again.
What Are Heat Cables and How Are They Used?
Heat cables—also referred to as roof cables, heat tape, or heat wires—are one ice dam prevention method that may be recommended. While proper insulation and ventilation are typically the best way to prevent ice dams (more on that below), this is sometimes not achievable due to the structural design of the building. In this case, heat cables are often recommended.
Heat cables are installed in a zig-zag pattern on the lower edge of the roof and near the gutters. The cables heat up, preventing ice from forming and keeping gutters clear to drain melting snow. Heat cables can be somewhat costly to install and run, but will significantly reduce ice dams when installed and used properly.
How to Prevent Ice Dams
Poor roof ventilation is one of the leading causes of ice dams, so the best ice dam prevention method is to ensure your building has proper insulation and ventilation. This can be achieved by:
- Replacing old insulation or adding more insulation to the attic and making sure the base of all roofing penetrations are properly sealed.
- Extending all ventilation systems through the roof, rather than allowing them to vent into the attic.
- Ensuring you have a proper vapor barrier installed between the roof decking and shingles.
The likelihood of ice dam formation can also be reduced by clearing snow from the roof using a roof rake. Removing as much snow as possible from the roof will help minimize snowmelt and reduce the likelihood of ice dams. Removal of snow with a roof rake should be done by a professional both for safety reasons and to reduce damage to shingles.