Snow Weight On Flat Roof

Flat roofs may be especially vulnerable to roof collapse depending on its engineered design load.

Snow weight on flat roof. Two feet of snow on a roof with a footprint of say 28 40 feet could weigh 45 000 pounds. Per square foot of roof space which is beyond the typical snow load capacity of most roofs. Two feet of old snow and two feet of new snow could weigh as much as 60 lbs. As snow falls it can accumulate on your flat roof putting unnecessary weight on the structure.

If your roof is pitched enter the length and width of the flat area covered by the roof. The roof deck collects the snow load and transfers the weight to the rafters. House roofs should support 20 lbs square foot of snow before they become stressed. Estimate the weight of snow on your roof.

That s more than 22 tons. Damages snow causes to flat roofs ponding bowing. What s the weight of snow on a roof. To calculate the weight of snow on a roof use the first two sections of our snow load calculator.

Snow won t slide off. You need to supply the following information. Contact your local building code department to determine the snow load requirements for your area. Since snow falls at slow steady speeds large quantities of snow can fall on the roof resulting in bowing.

Estimate how much weight your roof can support. For any rafter the portion of the roof deck that transfers this load is the tributary area. 3 5 inches of old snow is equal to one inch of water or about 5 lbs. Length and width of your roof.

Local building codes dictate the snow load required for residential roofs. You can enter these values in any units you d like including meters and feet.