Ice Dams

Given all the snow recently and cold temperatures you may be asking yourself “Do I need to shovel my roof to prevent ice dams?” The answer depends mostly on if you’ve had a history of issues with leaking in the past. Modern building science tries to limit the formation of ice dams so newer homes are less likely to have ice dams. To better understand, lets explore what causes an ice dam.

Modern roofs are considered “cold roofs” where the thermal envelope of the house (insulation) stops at the ceiling. If heat is escaping through a weak spot in that insulation it will cause the snow on the roof to melt. However, the soffit area of the roof is unheated so that water now freezes. This creates a cycle of water flowing and freezing which can creep under the shingles and eventually in to the house. To combat this, extra attention has been put in to constructing houses with adequate insulation near the bottom of the roof. Another common trouble spot are penetrations through the insulation like plumbing vents, electrical wires, and light fixtures. Adding insulation or sealing any leaks can prevent heat from escaping and melting the snow on the roof. Older homes are more likely to have less insulation in this key area and certain styles of house are more prone to ice dams then others. Lower pitched roofs are also more problematic because the water doesn’t run off as quickly. There is also more concern about the weight of the wet snow on a lower pitched roof.

If you do shovel your roof, it’s best to use a roof rake and not climb on the roof or use a ladder. You really only need to focus on the bottom edge and not the entire roof. It’s important to be careful of potentially damaging the shingles. Ice melt products like calcium chloride are the best option for removing an existing ice build up. Adding ice melting cables that plug in and generate heat are a good option for frequent problem areas but are difficult to install in the winter.