The Metrodome roof collapse might be the most famous cave-in caused by an over-accumulation of snow. But businesses all across the country suffer roof collapses when too much ice and snow build up.
Flat and low-slope roofs are far more susceptible to damage because snow can’t easily slide off the way it does on more steeply sloped roofs. This makes commercial properties especially prone to collapse.
One square-foot of dry snow weighs about three pounds, while wet snow can add anywhere from 12 to 21 pounds per square foot of weight on your roof. Weight adds up fast as snow accumulates.
Heavy snow load can put a dangerous level of stress on the structural integrity of a roof. Too much pressure can lead to cracked rafters, twisted trusses, and leaky ceilings. It can push a building out of plumb or trigger a total collapse.
Here’s what you can do to protect your business this winter:
Use a roof rake. For some shorter buildings, you can easily remove the snow by using a roof rake. Begin by raking the snow from the edges of the roof first in small amounts, and work toward the center. Don’t attempt to remove large amounts of snow at once, as it will be difficult to move and could injure you or someone else nearby as it falls. The goal of using a roof rake isn’t to remove all snow from the roof. Even removing some of the snow will help.
Check with an engineer. Even if you haven’t noticed any warning signs, it’s still a good idea to have your building evaluated for structural safety. A qualified engineer can offer recommendations for how often your structure should be evaluated based on its age and construction. Always consult an engineer if your building shows any sign of structural damage, like cracked trusses or rafters.
Hire professionals. Think twice before sending your regular maintenance team onto an icy, snowy roof to remove snow build-up. Contract with a professional firm that uses OSHA-approved fall protection and has proper insurance coverage for any rooftop work.
If you have a newer roof, double check with your roofing contractor to find the best way to remove snow from your roof without voiding the warranty.
A roof collapse can occur without warning. Protect your building and the people inside with prompt and proper snow removal. There’s no simple way to know how much snow is too much for your roof — it depends on the depth and density of the snow and the spacing of the rafters and trusses.
