Snow Weight On Flat Roof

For any rafter the portion of the roof deck that transfers this load is the tributary area.

Snow weight on flat roof.

3 5 inches of old snow is equal to one inch of water or about 5 lbs. The roof deck collects the snow load and transfers the weight to the rafters. That s more than 22 tons. Flat roofs may be especially vulnerable to roof collapse depending on its engineered design load.

As snow falls it can accumulate on your flat roof putting unnecessary weight on the structure. 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. Length and width of your roof.

To calculate the weight of snow on a roof use the first two sections of our snow load calculator. Estimate the weight of snow on your roof. If your roof is pitched enter the length and width of the flat area covered by the roof. What s the weight of snow on a roof.

Estimate how much weight your roof can support. Ice and snow will typically accumulate more quickly on low slope and flat roofs. House roofs should support 20 lbs square foot of snow before they become stressed. 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. Per square foot of roof space which is beyond the typical snow load capacity of most roofs. This down bearing pressure can cause the roof to bow and result in ponding under the roof structure. Damages snow causes to flat roofs ponding bowing.

Contact your local building code department to determine the snow load requirements for your area. Snow won t slide off.