In our case let s assume that our structure has a flat roof roof slope 5.
Ground vs roof snow oad.
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.
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.
This issue of live load vs.
The snow load that is applied to our structure is not the ground snow load but in most cases the flat roof snow load.
Asce 7 drift height calculation.
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.
Length of high roof lu.
From eave to ridge w.
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 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.
The basis for the snow load computation in asce 7 05 is the ground snow load.
If your roof is 1 000 square feet the total snow load is 15 000 pounds of snow.
The roof shall be designed for the live load indicated in table r301 6 or the snow load indicated.
Other considerations for sloped roofs can be found throughout chapter 7 of asce 7 10.
Figure 7 1 pages 84 85 and table 7 1 page 92.
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.
Ground snow load might seem somewhat confusing until you read the basic premise that is identified in irc section r301 6 which states.
Length of roof upwind of the snow drift.
The flat roof snow load is calculated using formula 7 3 1.
Roof snow load and the applicable snow.
The value used for the ground snow load should represent the snow load that has a 50 year mean recurrence interval or in other words a 2 probability of being exceeded in any given year.
Victor staley a building official in the town of brewster mass responds.
Even when the specification is clear regarding ground snow vs.
Purpose of this web site.
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.
The purpose of this web site is to provide ground snow load analysis information and data gathered from all 50 states.
Horizontal distance from eave to ridge.
