Ice dams are not just a problem for the Prairies. In the Fraser Valley, the Sea-to-Sky corridor and higher neighbourhoods across the Lower Mainland, winter snow followed by cold snaps can create ice dams that push water under your roofing and into your home. Here is what causes them, how to spot them, and how to prevent the damage.
What Is an Ice Dam?
An ice dam is a ridge of ice that forms along the lower edge of a roof. It happens when heat escaping from the house warms the roof deck and melts the snow above it. The meltwater runs down the roof until it reaches the colder eaves, where it refreezes. Over time, the ice builds up into a dam, and water from melting snow pools behind it.
Roofs are designed to shed water downhill, not to hold standing water. That pooled water can work its way under shingles and into the roof deck, attic, insulation and walls.
Where Ice Dams Are Most Common in BC
Ice dams are most likely in areas that get regular snow and freeze-thaw cycles, including Whistler, Squamish, Chilliwack, Abbotsford, Mission and Maple Ridge, as well as higher-elevation neighbourhoods on Burke Mountain and the North Shore. Even closer to the coast, a heavy snowfall followed by a cold week can cause them.
Warning Signs of an Ice Dam
- Thick ridges of ice along the eaves or in the gutters
- Large icicles hanging from the roof edge
- Water stains or damp spots on ceilings or exterior walls near the roof line
- Frost, damp insulation or water in the attic
- Peeling paint or swollen trim around windows below the eaves
What to Do If You Have an Ice Dam
- Don’t chip at the ice. Hammers, axes and shovels can easily damage shingles, flashing and gutters.
- Don’t climb onto an icy roof. It is extremely dangerous.
- Remove snow from the ground. A roof rake used safely from the ground can clear snow from the lower few feet of the roof and reduce further meltwater.
- Watch for leaks inside and contain any water to protect your home.
- Call a professional if water is getting in. Our team can provide emergency roof repair and assess any damage.
How to Prevent Ice Dams
The key to preventing ice dams is keeping the whole roof surface cold and evenly temperatured, so snow doesn’t melt and refreeze at the edges.
- Improve attic insulation to keep household heat from reaching the roof deck.
- Seal air leaks around attic hatches, pot lights, vents and chimneys.
- Ventilate the attic properly with balanced soffit and roof vents so cold air flows under the roof deck.
- Install ice and water protection membrane along the eaves and valleys when your roof is installed or replaced.
- Keep gutters clean so meltwater can drain freely.
- Book a pre-winter inspection to check ventilation, flashing and problem areas before the snow arrives.
Protect Your Roof This Winter
Whether you need a pre-winter roof inspection, better ventilation, or a new roof installed with proper ice protection, Great West Roof can help. Contact us or call (778) 578-7018.