Snow on the Roof!!

Tuesday, January 15th, 2019 by Robert Stiltner

One cubic foot of snow weighs as much as 15 pounds—and that doesn’t include the slushy stuff. Roofs are built to hold up to 20 pounds per square foot before straining under the load, but a big snowstorm can affect your roof and compromise its stability.

Now, there are two ways to prevent collapses due to snow accumulation: never letting snow pile up in the first place, and cleaning snow off in between storms. Use the tips below to learn how to protect your roof during icy and snowy winters.

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Snow’s Effect on Roofs

When the weight of snow and ice reaches 20–25 pounds per square foot, your roof can collapse. Use this chart to help you gauge snow and ice weights, so you can prevent a disaster.


Type of Snow Weight/Roof Stress
Fresh Snow 10–12 inches of fresh snow equates to one inch of water—or five pounds per square foot. It can snow up to four feet on your roof before it becomes a problem, but this number will be less if there is existing ice or snow before a storm.
Old Snow (Packed) Three to five inches of old snow equates to one inch of water—or five pounds per square foot of roof space. If you have two or more feet of old snow on your roof, it could be under great stress.

One inch of ice equates to one foot of fresh snow. An inch of ice also weighs about five pounds per square foot, so it poses the most risk to your roof because its thin and hard-to-see layers add a lot of weight.

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What to Look Out for this Winter

Unbalanced Snow Loads

Snowdrifts accumulate when wind pushes snow. Your chimney, HVAC, uneven portions of your roof, and other large features can become a trap for these drifts—causing certain parts of your roof to be loaded with more snow, which can weaken your roof.

Temperature fluctuation

When temperatures go above and below freezing, the snow on your roof will turn to ice and/or become more compact. This is also a prime way for ice dams to develop, which reach the eaves of your roofline and prevent snow from shedding naturally. Ice dams can also cause roof leaks.


Don’t forget your garage or sheds! All outbuildings have similar weight constraints and can collapse if snow becomes too heavy. In most cases, sheds and garages are easier to reach by ladder or foot, so it shouldn’t be too much of a problem to clear them off.


Snowy winters should be all about sledding, snowball fights, and warm cups of cocoa. Make sure this winter stays fun and dry by following these snow removal tips.

Products to help


Roof Rakes

Rake snow off your roof much like leaves off your lawn.These long-handled rakes allow you to remove snow from the safety of the ground. But be careful not to cause an avalanche on your head! Stand as far away as you can from the roof and use the rake to loosen the snow around the perimeter.

Calcium Chloride Tablets

Calcium chloride causes a chemical reaction that melts snow and ice. For the best results, use the roof-melt tablets regularly to prevent snow from piling up. You can find these tablets at most home and garden stores, or order the following products online. They’re multipurpose and can be used on sidewalks and patios too.

Roof Coating

Roof sealant won’t prevent snow from piling up on your roof, but it will caulk holes and cracks so water doesn’t seep in. Long before the first snow falls, hire a specialist to apply the following sealants to your shingles.

Steep Incline

If you live in a snowy climate, chances are your house was built with a steeper roofline. This makes it easier for the snow to shed naturally—rather than accumulate to hefty levels. If you’re building a home in a snowy area, you can incorporate a steeper pitch into the building plans. If not, use another tactic from this list to keep snow off your roof.

Metal Shingles

Tactile roof materials like asphalt shingles provide the traction snow needs to stay in place. To keep snow off your roof, consider installing metal roof panels or other slippery materials. Snow will fall off more naturally this way and you won’t have as much of an issue with snow build-up.

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Give us a call to help you out we can check the health of your roof or and give you a quote to coat your roof. 



our service area

We service Ashburn

Our Locations:

Colonial Contracting, Inc.
14171 Dave's Store Ln
Gainesville, VA 20155