How Roof Pitch Affects Snow Load

Homes in non snowy areas usually come with 20 lb.

How roof pitch affects snow load.

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. 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. Procedures and guidelines set out by asce in asce 7 10 give the structural engineer direction on what these loads are depending on your. 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.

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. The boca code recognizes this and allows you to use the horizontal projection of the roof when calculating snow loads. 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.

Roof pitch may have the most apparent effect on snow accumulation. A walk through on how to calculate roof snow loads per asce 7 10 the effect of snow loads on a structure can have dire implications if not taken into account during the design period. 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. Overestimation of snow loads can unnecessarily increase the cost of construction.

How snow load can damage your buildings. It s quite obvious that flat or low slope roofs will collect more. The roof or the entire structure can fail if the snow load exceeds the weight the building was designed to shoulder. In heavy snow areas where you might get 5 or 6 ft.

Snow load is the downward force on a building s roof by the weight of accumulated snow and ice. If your roof is 1 000 square feet the total snow load is 15 000 pounds of snow. Or the 25 psf snow load could be entered as a roof snow load with the unbalanced snow loading option turned off. 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.

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. Or if the building was poorly designed or constructed. Snow loads are influenced by elevation general weather and moisture patterns slope direction exposure roof or trail bridge configuration and wind direction and severity.