Snow Weight On Flat Roof

House roofs should support 20 lbs square foot of snow before they become stressed.

Snow weight on flat roof.

If your roof is pitched enter the length and width of the flat area covered by the roof. Estimate how much weight your roof can support. Since snow falls at slow steady speeds large quantities of snow can fall on the roof resulting in bowing. Local building codes dictate the snow load required for residential roofs.

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. Estimate the weight of snow on your roof. You need to supply the following information.

For any rafter the portion of the roof deck that transfers this load is the tributary area. 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. That s more than 22 tons.

The roof deck collects the snow load and transfers the weight to the rafters. You can enter these values in any units you d like including meters and feet. 3 5 inches of old snow is equal to one inch of water or about 5 lbs. Contact your local building code department to determine the snow load requirements for your area.

Snow won t slide off. As snow falls it can accumulate on your flat roof putting unnecessary weight on the structure. Length and width of your roof. Two feet of old snow and two feet of new snow could weigh as much as 60 lbs.

Two feet of snow on a roof with a footprint of say 28 40 feet could weigh 45 000 pounds. To calculate the weight of snow on a roof use the first two sections of our snow load calculator.