As it’s falling, snow looks light and beautiful. However, layer upon layer of fluffy snow can quickly become incredibly dense and heavy.
This weight can cause issues when shoveling, but it can also be dangerous if the snow piles up on a roof or deck.
Learning how heavy snow is and when it’s important to clear it away can help you save your home from damage.
How much does snow weigh?
In general, snow usually weighs about 20 pounds per cubic foot. You can also look at this in another way, which can sometimes be more useful for calculating snow’s weight compared to how much a structure can hold. Snow usually weighs about 1.25 pounds per 1 inch of depth, per square foot. This means that, if the snow is 10 inches deep, for example, a square foot area will have a weight of about 12.5 pounds.
The weight of snow can vary depending on the texture of the snow, how compacted it is, and how often it has melted and refrozen.
If it rains soon after a snowfall, or your area experiences slush or a wintery mix, the snow will often be much heavier after.
If the snow is new and fluffy and hasn’t had time to compress, a cubic foot of it might only weigh 1 pound, but wetter snow that has compressed and refrozen multiple times can weigh even more than 20 pounds per cubic foot.
In general, if there is a good deal of ice in the snow, you can increase the weight of 1 square foot of snow from 1.25 pounds to 5.2 pounds per 1 inch of depth.
How much snow can a roof hold?
On average, most roofs are equipped to hold about 20 pounds of weight, such as snow, per square foot.
This means that most roofs can hold about 16 inches of average-weight snow before the snow must be cleared away.
However, it’s a good idea to remove the snow before that, as the snow mixture might be heavier than you think.
Some roofs are designed to hold much more weight, and they might be able to hold up to 120 pounds per square foot.
To find out how much your roof can hold, you can check your building information or your local building codes.
Pitched roofs are often better equipped to hold snow, as a large amount of moisture runs off, which often leads to lighter snow and better weight distribution.
Snow should be removed from flat roofs as soon as possible to prevent puddling.
How much snow can a deck hold?
Most decks are designed to hold between 40 and 60 pounds of weight per square foot, which is equal to between about 2.5 and 4 feet of snow.
Again, the weight of the snow itself can vary greatly depending on how fresh it is and what the moisture and ice content is.
How do I know when to clear the snow from my roof or deck?
Clearing snow from a roof or deck can be tricky, but it’s a good idea to do it if it can be done safely.
Decks, in particular, should be cleared off periodically, as they are flat and puddling and refreezing can occur quickly.
Snow also compresses more easily on a flat surface. If you can, prep your deck for a snowstorm by tightening or fixing any loose boards or screws, and then shovel as much of the snow away after the storm as possible.
You can often tell that your roof needs to be cleared by looking for a few signs. If you see any water stains on the ceiling or notice any warping, either water from the snow is getting in or the weight is too heavy.
You may also see very large icicles, known as ice dams, forming outside your house. These ice dams often reach from the roof to the nearest surface, and they’re a sign that melting and refreezing are occurring.
Not only are these ice dams quite heavy, but they can also damage the shingles and gutters of your home.
You might also want to listen for any creaking, groaning, or popping noises from the roof, which is a sign that the weight of the snow is putting too much strain on the structure.