Take a load off

Protecting your roof from the weight of winter

[January 4, 2011]

Most of us winterize our vehicles and assure that we’re ready to remove snow from sidewalks, driveways and parking lots. But too often in our winter preparations, we fail to think about the roofs over our heads.

That’s understandable. It’s a rare winter in the Inland Northwest when the snow gets so heavy that it becomes a threat to structurally sound roofs. Yet, damage can happen, particularly when rain falls on deep snow. During the winter of 2008-2009, about 50 roofs collapsed in the city of Spokane alone, mostly on commercial buildings or carports and aluminum awnings.

Jaime Clark of Andre-Romberg Insurance said the claims for collapsed roofs that winter were unprecedented for the Spokane area. Some businesses were shut down for weeks and some for months.

For homeowners, “it’s not just the roof but personal property that’s damaged,” Clark said. “A lot of times they can’t live in the house until the repairs are done.”

Here are some things to keep in mind when it comes to protecting your roof this winter:

Do not go up on a roof to remove snow. It’s dangerous and your work with a snow shovel can cause damage. If the work must be done, leave it to a bonded and insured professional.
It’s rarely necessary to remove the snow from structurally sound pitched roofs. Flat or gently sloped roofs are at greater risk because they hold more moisture.
Businesses should hire structural engineers to assess the danger when snow piles up. Consider closing shop (as many businesses and schools did during the extreme winter of 2008-2009) until an expert says things are safe.
Collapsing roofs are not the only threat, or even the most common. Snow and ice sliding off roofs can break gas pipes or meters, or injure people on the ground.
Once winter is over, consider adding insulation and improving ventilation in your attic. That will help prevent the thawing and freezing that can lead to ice buildup, which often causes roofs to leak.
Insurance typically covers weather-related damage to homes and outbuildings, plus associated costs, such as temporary housing while repairs are made. Check with your insurance agent to make sure.

By the numbers

Although actual weights can vary greatly, a square foot of wet snow generally weighs about 1.25 pounds per inch of depth. Ice is a lot heavier, at about 5.2 pounds per inch of depth. Once you’ve got a rough estimate of the weight on your roof, you can determine whether it’s getting close to the load limit.

Roofs on most modern houses are built to withstand 30 to 40 pounds per square foot.

Older homes may not have been built to the same standards. But if a roof is in good shape and made it through earlier tough winters, such as 1968-1969, there’s no reason to believe it’ll have trouble during a typical year.

Manufactured homes, pole buildings and aluminum awnings typically come with documentation of their load capacity.

Resources

Media contact

Dan Hansen
Senior communications officer
Media spokesperson
(509) 344-2208
danh@stcu.org