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Getting Ready for Winter Part 3: How Much Snow Weight Can Your Roof Support?

At Grand Rapids Roofing by Premier Exteriors, we’re helping West Michigan Homeowners get ready to meet — and beat — old man winter. Though the leaves have barely started to turn, early-bird homeowners can help ensure their roof is ready to withstand the rigors of a Michigan winter.

In this primer, learn from the Insurance Institute for Business & Home Safety how to assess the risk of rooftop snow and ice accumulation.

If you’d like to inspect the condition of your roof before the snow flies, Call 616-534-7680 or Click for a FREE pre-winter roof inspection by Premier.

Evaluate Your Risk of Rooftop Snow/Ice Accumulation
Melting snow tends to more quickly run off of steep sloped roofs with slopes greater than 3 inches of slope in 12 inches of horizontal distance, particularly the steeper ones that are typically found on houses in northern climates. Ice and snow tend to more readily accumulate on low slopes and flat roofs over porches, lanais, or parts of a home that are next to a taller section of the house, especially during high winds.

How much snow is too much for your roof to handle?

Estimate How Much the Snow on Your Roof Weighs Using These Guidelines from IBHS

Fresh snow: 10–12 inches of new snow is equal to one inch of water, or about 5 lb per square foot of roof space, so you could have up to 4 feet of new snow before the roof will become stressed.

Packed snow: 3–5 inches of old snow is equal to one inch of water, or about 5 lb per square foot of roof space, so anything more than 2 feet of old snow could be too much for your roof to handle.

Total accumulated weight: 2 feet of old snow and 2 feet of new snow could weigh as much as 60 lb per square foot of roof space, which is beyond the typical snow load capacity of most roofs.

Ice: 1 inch of ice equals 1 foot of fresh snow.

Snow Removal May be Necessary to Avoid Roof Collapse

If you are in the “danger zone” according to the chart above or if the loads you estimate based on the thickness of the various types of snow and ice exceed 20–25 PSF, you should consider removing snow from your roof. For safe removal that won’t endanger you or damage your roof, use a snow rake with a long extension arm that will allow you to remove the snow while standing on the ground or hire a snow removal contractor.
from http://disastersafety.org/ibhs-risks-freezing-weather/prevent-roof-collapse-homes/