The equation for converting ground snow load p g to roof snow load p f is asce 7 05 equation 7 1.
Flat roof snow load formula.
If your structure has a sloped or flat roof you still need to calculate the flat roof snow load.
Snow load thickness density the result snow load or the pressure exerted by the snow has the units of kn m or lbs ft.
Consequently the roof design snow load is taken to be less than the ground snow load.
Snow weight length width cos pitch snow load the weight of snowis measured in kgor lbs.
The sloped roof snow load p s shall be obtained by multiplying the flat roof snow load p f by the roof slope factor c s.
The balanced snow load is applied everywhere where the roof structure is located.
This is highly regional as weights of snow for example range from 10 to 300 pounds per square foot based on moisture and volume of the snow.
Live roof load w wind load s snow load e earthquake load r rainwater load or ice water load t effect of material temperature h hydraulic loads from soil f hydraulic loads from fluids arch 331 note set 13 1 s2014abn 2 determining dead load from material weights.
This equation includes factors that take into account exposure and building heat loss.
Online snow load calculator for buildings with flat or low slope roofs for balanced snow drift and rain on snow surcharge loadings calculator asce 7 05 for structural engineers construction professionals and building planners.
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.
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.
This is all of the natural stresses imposed upon a roof such as snow loads rain loads and wind loads.
P g ground snow load l u length of upper roof l l length of lower roof h d height of snow drift w width of snow drift h b height of balanced snow load h c clear height from top of balanced snow load to closest point of adjacent roof h r height difference between roofs.
For roofs that are flat and with ground snow loads lower than 20 pounds per square foot the roof snow load is equal to 70 of the product of the exposure thermal and importance factors and the ground snow load.
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.
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.
