Griund Versus Roof Load

The flat roof snow load is calculated using formula 7 3 1.

Griund versus roof load.

Victor staley a building official in the town of brewster mass responds. The roof shall be designed for the live load indicated in table r301 6 or the snow load indicated. Table 1 1 page 3. 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.

Weight of permanent. Length of roof upwind of the snow drift. Figure 7 1 pages 84 85 and table 7 1 page 92. In our case let s assume that our structure has a flat roof roof slope 5.

Economical structural design in these areas requires an accurate prediction of the ground snow plus an understanding of how the snow is distributed on the roofs. The calculator will tell you the pounds per square foot of snow. The snow load that is applied to our structure is not the ground snow load but in most cases the flat roof snow load. Other considerations for sloped roofs can be found throughout chapter 7 of asce 7 10.

This issue of live load vs. Length of high roof lu. After that you ll need to use a snow load calculator. Ground snow load might seem somewhat confusing until you read the basic premise that is identified in irc section r301 6 which states.

Roof loads are a downward vertical force on the home. 70 60 50 40 35 30 25 x0 7 x0 7 x0 7 x0 7 x0 7 x0 7 x0 7 roof snow load. This downward imposed load on the home is also known as the snow load. The north zone middle zone and the south zone are identified on the roof load zone map above.

Sheikh taheri snow loading is the most severe test of roof structures in many parts of the state of idaho. Ground and roof snow loads for idaho by r. Then follow the instructions. Snow loads can be presented in two different ways.

It s quite easy to find one online. 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. Ground snow load pg. 1 0 importance factor i.

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. Enter the information requested like the rise and the roof ground snow load for your city exposure roof type etc. The truss could be designed based on the assumption that the 25 psf roof snow load is a factored ground snow load in which case a ground snow load is back calculated using asce 7 based on the specified roof snow load pg 25 psf therein lies the problem with specifying only a roof snow load. 49 42 35 28 24 5 21 17 5 assumed value thermal factor ct.

Roof load live load design is affected by the shape of the roof whether it is flat curved or pitched.