Snow Load And Tensile Roof

When discussing snow load with anyone it is crucial to have a clear understanding as to if the load is a ground or flat roof snow load.

Snow load and tensile roof.

Snow loads design snow loads shall be determined in accordance with chapter 7 of asce 7 05 but the design roof load shall not be less than that determined by section 1607. Or the 25 psf snow load could be entered as a roof snow load with the unbalanced snow loading option turned off. Once you know these values our snow load calculator automatically finds the total weight of snow on your roof. Victor staley a building official in the town of brewster mass responds.

When snow is plowed into piles on the structure or if ice accumulates due to clogged drains this load can be exceeded. For roof designs snow loads varying from 10 to 40 psf are commonly used. Snow load thickness density. Therefore the reduction of live loads for tributary area in section 1607 11 2 is not permitted.

This issue of live load vs. 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. Garages are normally designed for a roof live load of 60 to 80 pounds per square foot. Snow can either blown from the low side of the roof towards the high side or is blown off the higher area of the roof onto the lower projected side.

Oregon requires a minimum roof snow load of 20 psf pm in asce7 for all roofs plus a 5 psf rain on snow surcharge for many roof types resulting in a 25 psf minimum roof design load for most roofs. Overestimation of snow loads can unnecessarily increase the cost of construction. If you want to calculate these values by hand use the following formulas. Only the properly adjusted loads can be used to design roof structural elements.

The amount of additional snow load or surcharge depends on the difference in height of the two adjacent roofs and the lengths of roof perpendicular to the drop in height. The roof shall be designed for the live load indicated in table r301 6 or the snow load indicated. Snow loads are influenced by elevation general weather and moisture patterns slope direction exposure roof or trail bridge configuration and wind direction and severity. Snow load is an environmental load not a live load section 1602.

You can also find the load per square meter or square foot of roofing by opening the advanced mode. 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. See the map usage notes or snow load analysis for oregon part. Ground snow load might seem somewhat confusing until you read the basic premise that is identified in irc section r301 6 which states.