Roof Overhang Wind Loads

Asce 7 10 provides two methods for wind load calculation.

Roof overhang wind loads.

A simplified procedure and an analytical procedure. The norwegian code of practice 3 regarding wind forces is mainly based on wind tunnel experiments done by jensen and franck 4. The remainder of zone 2 2e extending to the ridge line shall use the pressure coefficient gcpf for zone 3 3e. Roof shape and slope are both important parameters for the safety of a structure especially when facing wind loads.

For transverse load case the roof pressure coefficient gcpf when negative in zone 2 or 2e shall be applied in zone 2 2e for a distance from the edge of the roof equal to 0 5 times the horizontal dimension of the building parallel to the direction of the mwfrs being designed or 2 5 he at the windward wall whichever is less. The simplified procedure is for building with a simple diaphragm roof slope less than 10 degrees mean roof height less than 30 feet 9 meters regular shape rigid building no expansion joints flat terrain and not subjected to special wind condition. An overhang is an unenclosed continuation of the roof surface. This procedure addresses roof overhangs via footnote 8 on figure 28 6 1.

The present study demonstrates the pressure variations due to wind load on the pyramidal roof of a square plan low rise building with 15 wall openings through cfd computational fluid dynamics simulation. Examples of components include fasteners purlins girts studs roof decking and roof trusses. Upper and lower are simultaneously subjected to wind action. Where zone e or g falls on a roof overhang on the windward side of the building use eoh and goh f or the pressure on the horizontal projection of the overhang.

Components can be part of the mwfrs when they act as shear walls or roof diaphragms but they may also be loaded as individual components. Most impotently wind load on overhangs is very critical as both of the surfaces i e. Components receive wind loads directly or from cladding and transfer the load to the mwfrs. Few studies concerning the effect of roof overhang on the flow pattern and wind loads of typical low rise buildings have been made 1 2.

Particularly on low rise residential applications overhangs may be open or covered by a soffit and may be cantilevered or supported. Overhangs on the leeward and side edges shall have the basic zone pressure applied.