Roof Snow Load Requirements

A clay tiled roof may have a dead load.

Roof snow load requirements.

In our case let s assume that our structure has a flat roof roof slope 5. Schilke civil agricultural engineering montana state university august 1989. The 20 psf load is equivalent to 14 inches of snow at the design density while the 25 psf load is 17 inches. This downward imposed load on the home is also known as the snow load.

The residential code of ohio which applies to one and two family homes shows a map indicating the required snow load. Intermediate values may be interpolated by proportion. The minimum design roof snow load after allowed reductions shall be 30 psf. The north zone design live load equates to 40 pounds per square foot the middle zone equates to 30 pounds per square foot and the south zone equates to 20 pounds per square foot.

Flat roof snow load pf. The snow load that is applied to our structure is not the ground snow load but in most cases the flat roof snow load. Unfortunately most buildings constructed during those years 1970 2000 do not even meet the 40 psf requirement. The standard practice for a few decades in new hampshire was to build our roofs to support 40 pounds per square foot psf live snow load.

The north zone middle zone and the south zone are identified on the roof load zone map above. Drift load design in the 30 psf zones may utilize asce 7 16 table c7 1 ground snow values. In areas where the ground snow load pg exceeds 10 pounds per square foot psf 0 479 kn m 2 the following additional information shall also be provided regardless of whether snow loads govern the design of the roof. Why snow load information.

It calls for 20 psf throughout most of ohio and 25 psf along a north south strip in the eastern half of the state. Other considerations for sloped roofs can be found throughout chapter 7 of asce 7 10. The flat roof snow load is calculated using formula 7 3 1. The load increases with the use of heavier roofing material.

That s about 4 feet of powder and as little as 2 feet of wet snow. The final roof design loads shall not be less than 20 psf after all reductions are factored except for lyon storey counties. A great deal of confusion currently exists among engineers architects recreation specialists and maintenance personnel concerning the proper snow loading to use for the design and maintenance of trail bridges building roofs and other structures in mountainous high snow load areas. Ground snow loads p g for northern nevada locations 1.

1603 1 3 roof snow load data the ground snow load pg shall be indicated. Table r301 2 1 climatic and geographic design criteria ground snow load.