Roof Snow Removal and Ice Dams

When should you clear snow from your roof?

Most roofs are designed for local snow loads, but heavy wet snow, rain on snow and drifting can overload a roof, especially flat roofs, older buildings, carports and chalets that stay empty for weeks. As a rule of thumb, have your roof checked when snow gets very deep or after freezing rain, and act immediately if you notice warning signs.

Warning signs of snow overload

• Cracking or popping sounds from the roof structure
• Interior doors that suddenly stick or will not close
• New cracks in ceilings or walls
• A visible sag in the roofline or ceiling
• Water infiltration around the eaves

If you see these signs, leave the building and call a professional.

What causes ice dams

Heat escaping from the house warms the roof deck and melts snow. The water runs down to the cold eaves, refreezes and forms a ridge of ice. Water then backs up under the shingles and leaks into walls and ceilings. Long icicles along the gutters are a classic sign.

How to prevent ice dams

• Improve attic insulation and seal air leaks around light fixtures, hatches and chimneys.
• Make sure the attic is well ventilated (soffit vents and roof or ridge vents).
• Install an ice-and-water membrane along the eaves when you redo the roof.
• Use a roof rake from the ground to remove the first metre of snow at the eaves.

Doing it yourself vs hiring a pro

Roof snow removal is dangerous. Work from the ground with a roof rake when possible. Never use a metal shovel or ice pick on shingles or membranes. For flat roofs, steep roofs and two-storey homes, hire an insured company that uses proper fall protection.