Snow On Roof Weight Distribution

So while a cubic foot of fresh powder might weigh in at 7 pounds that same amount of wet packed snow could be more like 20.

Snow on roof weight distribution.

All these variants create a challenge for determining safe snow loads. One inch of snow may weigh anywhere from one quarter pound per square foot to one and three quarter pounds per square foot. You can also find the load per square meter or square foot of roofing by opening the advanced mode. Per square foot of roof space which is beyond the typical snow load capacity of most roofs.

Only one inch of ice weighs in at just under five pounds per square foot almost five times an average snow s weight. 3 5 inches of old snow is equal to one inch of water or about 5 lbs. Ground snow load value. If you want to calculate these values by hand use the following formulas.

When designing and building a new roof you should give consideration to any face of the of the home that s going to be sheltered from the wind or precipitation as this can impact the distribution of roof snow load as it accumulates. How much snow can a roof hold. Where snow isn t a problem the live load can come from people working on the roof and any equipment they take on to the. Step 4 determine the flat roof snow load.

Snow load thickness density. Once you know these values our snow load calculator automatically finds the total weight of snow on your roof. Two feet of old snow and two feet of new snow could weigh as much as 60 lbs. The live load on a roof is the weight of any temporary objects on the roof.

It could weigh over 20 pounds if it s wet and compacted. Consider removing accumulated snow from your roof to avoid collapse. For roofs that are flat and with ground snow loads lower than 20 pounds per square foot the roof snow load is equal to 70 of the product of the exposure thermal and importance factors and the ground snow load. On multiple factors including.

S 1 25 p where s is the number of inches of snow on your roof and p is the pounds per square foot of that snow. A cubic foot of snow can weigh about 7 pounds if it s dry and fluffy. Wet snow can be nearly three times heavier than dry fluffy snow. Additionally if snow falls unevenly on the roof then of course the weight distribution of the accumulation is going to be uneven which poses and even greater risk.

On average two feet of snow can equal up to 19 tons of weight on your roof which can significantly weaken the structure. Wind exposure of roof. Roof snow load is defined as the weight of snow on the roof surface used in design of the building structure ibc 2012. Importance occupancy and use of the building.

Two feet of snow on a roof with a footprint of say 28 40 feet could weigh 45 000 pounds. That s more than 22 tons.