Snow On Roof Weight

A roof in an older building may be underbuilt and therefore more vulnerable to structural problems.

Snow on roof weight.

1 foot of snow on the roof 8 000 lbs 4 tons 7 psf 2 feet of snow on the roof 16 000 lbs 8 tons 14 psf 3 feet of snow on the roof 24 000 lbs 12 tons 21 psf. How much does snow weigh on a roof. Roof collapse due to overloading by snow is a primary concern of people looking up the weight of snow. Calculating the weight of snow is useful when you need to know the total weight it adds for example to calculate the weight on a roof.

But usually the buildings that are collapsing from snow are usually outbuildings with flat roofs and collapse due to. For in depth information on this topic please see the links available on our page snow issues and roofs. For any rafter the portion of the roof deck that transfers this load is the tributary area. Consider removing accumulated snow from your roof to avoid collapse.

The critical factor with the roof collapsing and damaging is the weight of the snow and not the depth of the snow on your roof. Here are a few examples of the weight of snow on a roof. For an average size roof about 2000 square feet covered in heavy wet snow a good rule of thumb is the weight of one compact suv 3 470 lbs on your roof for every 1 inch of snow. Fresh light and fluffy snow will weight much less than the dense packed or wet variety.

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. Rain sleet and ice add to the. If you live in the us our snow load calculator compares the total weight on your roof with the permissible load calculated according to the standards issued by the american society of civil engineers regarding the minimum design loads for buildings and other structures asce7 16. Psf pounds per square foot.

Snow which is just frozen ice crystals varies in weight by its volume and density. On average two feet of snow can equal up to 19 tons of weight on your roof which can significantly weaken the structure. All numbers are approximate. Snow loading is the downward force exerted on structures by the weight of accumulated snow.

It is also important to remember that that math doesn t take into account any ice you have on your roof which weighs much more than heavy wet snow weighs.