Safe Snow Removal for Metal Roofing
Protecting Your Metal Roof This Winter
Heavy snowfall can create beautiful winter scenery, but for building owners and facility managers, it also introduces important considerations about roof safety and structural performance. The Metal Building Manufacturers Association (MBMA) provides helpful guidance in its Metal Building Systems Manual to support the winter protection of your Metallic metal building.
When Does Snow Become a Concern?
Every metal roof is engineered to handle a specific snow load based on local building codes. In areas with milder winters, this requirement may range from 10 to 20 psf. Colder regions with harsher winters can require snow load capacities of more than 40 psf. Because snow density varies widely, estimating actual roof weight is not always straightforward. Light powder weighs far less than dense, moisture-filled snow.
As a conservative general guideline, MBMA suggests assuming at least 5 pounds per square foot per inch for heavy, wet snow. For example, a roof designed for 20 psf could reach its intended limit with only 4 to 5 inches of dense accumulation. Always consult a structural engineer to verify your building’s load limits and to understand typical snow-density values in your specific region.
How Roof Pitch Impacts Snow Accumulation
Roof slope directly affects the way snow collects, melts, and moves.
- Steep roofs with a pitch greater than 4:12 often shed snow naturally once sunlight or interior heat creates a slick surface.
- Low-slope roofs with a pitch below 4:12 tend to retain snow for longer periods, allowing it to compact and potentially freeze into heavier layers of ice.
Pay close attention to areas where snow can drift. This includes parapets, curbs, chimneys, elevation changes, and rooftop equipment. These areas can carry loads several times higher than the rest of the roof. Trapped snow can also rise above flashings, increasing the chance of leaks during thaw cycles.
Best Practices for Removing Snow
When accumulated snow reaches potentially unsafe levels, partial removal is the recommended approach. MBMA advises avoiding metal shovels, ice picks, and sharp tools because they can scratch protective coatings, puncture roof panels, or void warranties.
Use the following best practices instead:
- Remove only the excess snow. Leave a thin and uniform layer of about 2 to 3 inches to protect the roof surface.
- Start with areas that have high drifts, then work evenly across the roof to maintain a balanced load.
- Avoid moving snow from one part of the roof to another, which can unintentionally overload specific sections.
Keeping Your Crew Safe
Snow-covered metal roofs present significant safety concerns. Always use proper fall protection, secure access points, and ensure that ladders remain stable. Snow can conceal roof edges, skylights, and penetrations, so crews should move carefully and deliberately. Removing snow early while it is still light and manageable reduces strain on workers and helps prevent the formation of ice.