How Roof Pitch Affects Snow Load

In heavy snow areas where you might get 5 or 6 ft.

How roof pitch affects snow load.

Overestimation of snow loads can unnecessarily increase the cost of construction. The boca code recognizes this and allows you to use the horizontal projection of the roof when calculating snow loads. Snow loads are influenced by elevation general weather and moisture patterns slope direction exposure roof or trail bridge configuration and wind direction and severity. An inch of ice for example topped with 2 feet of packed snow and a foot of fresh snow can carry a load of 50 psf which is well beyond the 20 psf load code.

How snow load can damage your buildings. Building methods to protect against snow accumulation. If your roof is 1 000 square feet the total snow load is 15 000 pounds of snow. 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.

Steel buildings are perfectly suited for handling the heavy snowfall in these northern states but it s important to get an accurate snow load estimate to ensure your steel building won t fail under the pressure. Calculating a snow load can be complicated as several factors come into play including the type of snow the weight of snow and the shape of your roof among other things. Or if the building was poorly designed or constructed. Boca also allows you to reduce the snow load for roofs with slopes greater than 30 degrees presumably because snow will slide or blow off steeply pitched roofs.

Or the 25 psf snow load could be entered as a roof snow load with the unbalanced snow loading option turned off. Roof pitch may have the most apparent effect on snow accumulation. If the snow weighs 10 pounds per cubic foot and there are 1 5 feet on the roof each square foot of the roof is getting 15 pounds of pressure. It is something you have to pay attention to in areas with snow.

If unbalanced snow loading isn t required or specified the truss designer may enter the 25 psf snow load as a top chord live load tcll set the load duration factor to 1 15 for snow and turn snow loading off completely. Beefing up the strength of the roof so it will hold more weight is not done by adding roofing material or sheathing but by adding rafters. To figure out the load on your roof take the depth of snow in feet and multiply it by the weight of a cubic foot of snow. Procedures and guidelines set out by asce in asce 7 10 give the structural engineer direction on what these loads are depending on your.

For dead loads you are correct. The roof or the entire structure can fail if the snow load exceeds the weight the building was designed to shoulder. It s quite obvious that flat or low slope roofs will collect more.