Snow Weight On Flat Roof

Estimate the weight of snow on your roof.

Snow weight on flat roof.

Two feet of old snow and two feet of new snow could weigh as much as 60 lbs. Since snow falls at slow steady speeds large quantities of snow can fall on the roof resulting in bowing. House roofs should support 20 lbs square foot of snow before they become stressed. As snow falls it can accumulate on your flat roof putting unnecessary weight on the structure.

For any rafter the portion of the roof deck that transfers this load is the tributary area. Estimate how much weight your roof can support. Ice and snow will typically accumulate more quickly on low slope and flat roofs. Per square foot of roof space which is beyond the typical snow load capacity of most roofs.

Two feet of snow on a roof with a footprint of say 28 40 feet could weigh 45 000 pounds. Flat roofs may be especially vulnerable to roof collapse depending on its engineered design load. Per square foot of roof space so anything more than 2 feet of snow could be too much for your roof to handle. You can enter these values in any units you d like including meters and feet.

Length and width of your roof. You need to supply the following information. 3 5 inches of old snow is equal to one inch of water or about 5 lbs. Local building codes dictate the snow load required for residential roofs.

Snow won t slide off. Damages snow causes to flat roofs ponding bowing. This down bearing pressure can cause the roof to bow and result in ponding under the roof structure. What s the weight of snow on a roof.

Contact your local building code department to determine the snow load requirements for your area. To calculate the weight of snow on a roof use the first two sections of our snow load calculator.