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.
Ground vs roof snow oad.
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.
The flat roof snow load is calculated using formula 7 3 1.
70 60 50 40 35 30 25 x0 7 x0 7 x0 7 x0 7 x0 7 x0 7 x0 7 roof snow load.
Length of roof downwind of the snow drift.
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.
Purpose of this web site.
Horizontal distance from eave to ridge.
The snow load that is applied to our structure is not the ground snow load but in most cases the flat roof snow load.
The purpose of this web site is to provide ground snow load analysis information and data gathered from all 50 states.
Other considerations for sloped roofs can be found throughout chapter 7 of asce 7 10.
Length of low roof ll.
From eave to ridge w.
1 0 importance factor i.
Weight of permanent.
In our case let s assume that our structure has a flat roof roof slope 5.
The determination of the drift load that is required for unbalanced snow load cases requires the use of the ground snow load pg not the roof snow load.
1 0 exposure factor ce.
In my region on cape cod we have a ground snow load design of 25 psf which is a greater design load than the live load 12 psf to 20 psf over an entire roof system.
Snow loads can be presented in two different ways.
Figure 7 1 pages 84 85 and table 7 1 page 92.
Length of high roof lu.
Sheikh taheri through years of research.
Ground and roof snow loads for idaho 1986 this report was compiled by ron sack and a.
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.
Each state has a listing of building code and applicable guidelines for snow loads as well as details about where the snow load information may be found or purchased.
If the ground snow load isn t specified then a ground snow load needs to be assumed and the truss designer and the building designer may not be on the same page as it relates to this design assumption.
If your roof is 1 000 square feet the total snow load is 15 000 pounds of snow.
The bottom line is that the irc requires you to design the roof structure to the greater roof load and in my region that s the ground snow load.
Ground snow load or roof snow load snow load.
It was released in 1986 by the department of civil engineering at the university of idaho.
49 42 35 28 24 5 21 17 5 assumed value thermal factor ct.
