Snow Loads

12/13/2019 (Permalink)

Snow Load on Roof

FEMA has a great source (Snow Load Safety Guide 2013) for determining what would be considered a safe snow load on your roof. It was designed for pretty much anyone responsible for safety and maintenance of a home or building.

A snow load is the amount of snow on your roof top. The load is not necessarily determined by one event, but by as many events as occur whereby the snow load accumulates.

The weight of snow is not measurable by the number of inches, but by the moisture content within the snow itself. If you have 1" of dry snow, the weight of that 1" would be approximately 3 lbs per sq ft, where as 1" of a wet snow may weigh approximately 21 lbs per sq ft. On the other hand, an ice storm event may raise that 1" accumulation to 57 lbs per sq ft. Considerable differences.

One major concern of a snow load is the weight exceeding the structural capacity. Drifting or the sliding of snow to specific areas of your roof could increase the risk of damage through accumulated weight.

How do you prevent this from becoming an issue? Snow removal. If you don't have one, get yourself a roof shovel or roof rake. Takes some effort, but is an effective, preventive tool and measure worth taking.