In our case let s assume that our structure has a flat roof roof slope 5.
Flat roof snow load.
Once you have the ground snow load p g you can compute the flat roof snow load p f.
The flat roof snow load ρ f on a roof with a slope equal to or less than 5 degrees 0 09 rad 1 inch per foot 4 76 degrees shall be calculated in accordance with section 7 3 of asce 7.
Flat roof snow loads p f the snow load that is applied to our structure is not the ground snow load but in most cases the flat roof snow load.
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.
This is all of the natural stresses imposed upon a roof such as snow loads rain loads and wind loads.
Other considerations for sloped roofs can be found throughout chapter 7 of asce 7 10.
If you want to calculate these values by hand use the following formulas.
The following are the equation for determining snow loaing on flat roofs.
First figure out how deep the snow is piled up there.
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 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.
Flat roof snow load are determined by the following method.
Underestimation of snow loads can result in premature failure high maintenance costs resource damage and in some cases safety issues.
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.
You need to use a snow load formula for flat roofs.
You can also find the load per square meter or square foot of roofing by opening the advanced mode.
Pg is converted to pf by this formula.
0 7 x ce x ct x is x pg pf.
In colder regions the design snow load represents snow deposited by multiple snow events.
Wind loads depend on wind speed and can vary as widely as the snow.
The snow load p f on a roof with a slope equal to or less than 5 degrees 1 in ft 4 76 deg shall be calculated in lb ft 2 kn m 2 using the following formula.
Once you know these values our snow load calculator automatically finds the total weight of snow on your roof.
If your roof is flat it is more likely to have snow load problems than if it is pitched.
Often changes of five or 10 pounds per square foot result in minimal differences in cost.
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.
Snow load thickness density.
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.
