When to clear snow off the roof, boycotting snow loading and roof failures

Snow on roof. (FILE)

As heavy snow continues across parts of the region, building owners and employers are being reminded to pay close attention to snow accumulation on rooftops. Proactive inspections and safe snow-clearing practices can help prevent injuries, damage, and potentially fatal collapses.

Snow loads can build quickly

Did you know that a single cubic foot of new snow can weigh about seven pounds? While older, compacted snow may weigh up to 30 pounds.

“Rain falling on accumulated snow will add even more weight. Drifting snow may put excessive loads on the areas where it piles up, for example against equipment or penthouses or at walls between roof levels,” stated The Ministry of Labour, Training and Skills Development.

The ministry advises that roofs should be assessed by a professional engineer when snow accumulation appears heavy or when there are visible signs of structural distress, like bending, cracking, or twisting.

If a roof is overstressed, officials say safe snow removal procedures should be put in place immediately.

Clearing snow safely

Snow removal itself carries many risks. According to the ministry, clearing should be done in a way that avoids uneven or concentrated loading, which can trigger a collapse.

If snow is being cleared from a roof, it must be secured to protect people below, and workers on rooftops must use proper fall-arrest or travel-restraint systems under provincial regulations.

Officials also recommend consulting a civil or structural engineer to determine whether snow loads are excessive.

The County of Simcoe recommends having snow removed from rooftops once it piles up beyond two to three feet, or 60 to 90 centimetres, to prevent structural issues.