Roof Load Analysis

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.

Roof load analysis.

Roof live loads largest roof loads typically caused by repair and maintenance pitch rise span lr 20 r1r2 12 lr 20 lr horizontal projection roof live load 16 r 1 r 2 live load reduction factors r 1 accounts for size of tributary area of roof column a t r 2 effect of the roof rise. First figure out how deep the snow is piled up there. To do this i use conservative too heavy dead loads and full snow loads regardless of pitch. Technically you should use the actual rafter length when adding up the weight of roofing materials.

Loads on buildings and structures. However in my practice i typically use the horizontal run of the roof for both types of load. This means that one is a fixed node and the other is a rolling node. A fixed node will provide support in both directions down the length of the roof truss members often called the x and y directions.

In order for a roof truss load to be stable you need to assign two of your nodes on each truss to be support nodes. Roofs are under a lot of pressure. For dead loads you are correct. The live loads used for the structural design of floors roof and the supporting members shall be the greatest applied loads arising from the.

If your roof is flat it is more likely to have snow load problems than if it is pitched. Step 4 determine the flat roof snow load. Other considerations for sloped roofs can be found throughout chapter 7 of asce 7 10. Tornadoes special dynamic or hydrodynamic loads etc site specific or case specific data or analysis may be required to determine the design loads on them.

You need to use a snow load formula for flat roofs. 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. 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. 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.

However this load combination rarely governs the design of light frame construction. In our case let s assume that our structure has a flat roof roof slope 5. Load limits on the roof of a building. In order to stay intact and in place a roof must be able to resist loads both permanent and temporary that are pushing.