Griund Versus Roof Load

In our case let s assume that our structure has a flat roof roof slope 5.

Griund versus roof load.

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. Ground snow load pg. Ground snow load might seem somewhat confusing until you read the basic premise that is identified in irc section r301 6 which states. Victor staley a building official in the town of brewster mass responds.

This downward imposed load on the home is also known as the snow load. It s quite easy to find one online. 1 0 exposure factor ce. Ground and roof snow loads for idaho by r.

Sheikh taheri snow loading is the most severe test of roof structures in many parts of the state of idaho. The north zone middle zone and the south zone are identified on the roof load zone map above. Length of high roof lu. 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.

Then follow the instructions. The flat roof snow load is calculated using formula 7 3 1. The determination of the drift load that is. Enter the information requested like the rise and the roof ground snow load for your city exposure roof type etc.

Roof load live load design is affected by the shape of the roof whether it is flat curved or pitched. 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 calculator will tell you the pounds per square foot of snow. 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.

70 60 50 40 35 30 25 x0 7 x0 7 x0 7 x0 7 x0 7 x0 7 x0 7 roof snow load. Snow loads can be presented in two different ways. Ground snow load or roof snow load snow load. Figure 7 1 pages 84 85 and table 7 1 page 92.

The roof shall be designed for the live load indicated in table r301 6 or the snow load indicated. 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. Table 1 1 page 3. 1 0 importance factor i.

Other considerations for sloped roofs can be found throughout chapter 7 of asce 7 10. This issue of live load vs. Length of roof upwind of the snow drift. The snow load that is applied to our structure is not the ground snow load but in most cases the flat roof snow load.

49 42 35 28 24 5 21 17 5 assumed value thermal factor ct.