Ice dams and roof snow: when winter buildup becomes a building problem
How ice dams form, why roof snow and freeze-thaw cycles matter, and what information to provide when requesting professional roof help.
Updated September 28, 2026How an ice dam forms
Natural Resources Canada explains that snow can melt where roof sheathing is warmed from below, then refreeze near a colder overhang. The resulting ice mass can trap later meltwater and allow water to back up beneath roofing materials.
Roof work has its own safety risk
Canada’s winter-preparedness guidance recommends working in pairs or hiring a professional for roof and eavestrough clearing. Icy ladders and roof surfaces add fall risk to an already difficult job.
What to include in a roof request
Photos and a short description can help a provider triage the request before arriving.
- Roof type and approximate height
- Where snow or ice is concentrated
- Any ceiling stain or active leak
- Access limitations and areas below the roof edge