Flat Roof Snow Load

For ground snow loads greater than 20 pounds per square foot the roof load is equal to 70 of the product of the exposure thermal and importance factors the ground snow load and 20 pounds.

Flat roof snow load.

Length of roof downwind of the snow drift. Flat roofs must be installed on a very specific mild slope so that the water can drain off properly and if the drains and scuppers aren t cleared regularly this increases the chance of a leak. E 1 2 flat roof load p g 10 outline minimum roof snow load thermal factor unbalanced load drift load on adjacent roof parapet wall rtu drift sliding load on adjacent roof ponding faq s 11 unbalanced loads gable roof upper limit roof slope change lower limit roof slope simplify small eave to ridge distance change 12. The easiest way is to push a yardstick into the snow on the roof selecting an area that looks typical of the overall snow depth.

This is the snow load calculated in the previous section. Snow is actually one of the easiest to design for and all. If your roof is flat it is more likely to have snow load problems than if it is pitched. Length of roof upwind of the snow drift.

In regions with relatively low snow load values the load from a single event may result in the peak loading. First figure out how deep the snow is piled up there. 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. As a result equation 7 1 which accounts for loss between events will result in a non conservative value.

A flat roof is no more or less likely to leak than a pitched roof it all comes down to the design and the competence with which it is installed. After you obtain the roof slope factor from those sections in asce 7 10 the balanced design snow load for the sloped roof can easily be calculated using equation 7 4 1. Certainly the weight of snow can add up but your home must support a variety of loads. If your structure has a sloped or flat roof you still need to calculate the flat roof snow load.

Minimum flat roof snow load values. The balanced snow. Length of low roof ll. You need to use a snow load formula for flat roofs.

Figure 7 1 pages 84 85 and table 7 1 page 92. Ground snow load pg. Length of high roof lu. Flat roofs can t possibly support all the extra weight a totally valid concern but rest assured your architect and engineer have this in mind when designing the roof structure.

Wind seismic building weight furniture occupants etc. From eave to ridge w. If you have any concerns as you are determining your flat roof snow load consult with a structural engineer or roofing specialist. Pf is flat roof snow load if as a consumer your concern is snowfall and you want to upgrade the ability of your building to carry it this is the value to increase.