Lots of rain, a little snow, a sunny day but cold temperatures, then more snow – yes, it definitely feels like winter has arrived. While icicles and ice end up on the gutters, contrary to popular belief, a debris-filled gutter system is not the cause of ice damming. Several contributing factors occur in combination to create ice dams on roofs in the Lower Mainland. What are ice dams and what can you do about them?
Ice dams generally form on the edge of a roof as the snow melts from the bottom up. They can also be found around skylights and vents and in roof valleys. A slight rise in temperature or heat escaping from the attic warms up the snow; when cold air meets the runoff, it can freeze again, preventing additional snowmelt from running freely off the roof and entering the gutters.
As temperatures fluctuate, more snowmelt occurs. Because of the ice dam, there’s nowhere for the water to go, causing it to back up behind the ridge of ice. Water being pushed in behind roofing shingles can result in water damage to interior and exterior walls, ceilings, and insulation. Ice dams can also cause structural damage to the roof itself.
Ice Dams and Gutters
Since ice dams typically run along the roofline, the process of water thawing and refreezing adds layers to the ice formations. While icicles might look pretty, they weigh the gutters down, putting more stress on fasteners and fascia where gutter sections are attached. When ice buildup dents the gutters, moisture can form in the damaged gutter sections, further weakening the gutter system.
Dealing with Ice Dams – Don’ts
Chipping away: It is not advisable to use a hammer, chisel, axe, ice pick or shovel, because they can potentially damage and/or dislodge roofing tiles, fascia, and gutters.
Salt: Using salt will actually do your landscaping more harm in the spring than have any noticeable effect on the ice dam.
Chemical deicers: Unless you are able to test specific areas and materials, it’s best to skip chemical deicers, particularly if you don’t know what the roof is made or the type of metal the brackets and fasteners are.
Dealing with Ice Dams – Dos
Snow removal: Remove snow with a roof rake to prevent further ice damming. If the house is two or more storeys, use a roof rake with an extension pole.
Heat: Install a deicing kit; it typically consists of a length of cable and hardware to secure it in place.
Roof temperature: Since the main cause of ice damming is heat escaping from the home, a long-term fix is to keep the roof the same temperature as the eaves. Ways to accomplish this include: adding insulation to the attic; increasing ventilation; and preventing air leakage from anywhere that will warm the underside of the roof.