Roof Overhang Wind Pressure

Canopies with less than 50 obstructions below the roof surface would be considered clear.

Roof overhang wind pressure.

Qz 0 613 kz kzt kd v2 n m 2. The effective wind area should be the maximum of. 0 10 20 and 30 and the highest negative area weighted pressure coefficient was found to be 0 540 for 10 roof slope with 0 wind incidence angle on face a. Overhangs roof truss tails zone 2 p 20 1 2 2 44 2 psf use trib area of tail zone 3 p 20 1 2 5 50 3 psf roof deck at overhangs zone 2 p 20 1 2 2 44 2 psf zone 3 p 20 1 3 7 74 4 psf.

For the leeward overhang the coefficient for the leeward wall c p 0 5. Obstructed wind flow is considered when 50 or more of the area below the surface of the roof is composed of objects inhibiting wind flow such as a canopy atop a concrete basin at a wastewater treatment plant. When building a structure it is important to calculate wind load to ensure that the structure can withstand high winds especially if the building is located in an area known for inclement weather. Wall 27 5 psf roof 6 5 psf end zone.

In order for a structure to be sound and secure the foundation roof and walls must be strong and wind resistant. Kz is velocity pressure exposure coefficient. Wind induces suction almost over the entire pyramidal roof of square plan building models for all roof slopes i e. Since trusses are spaced at 26ft hence this will be the length of purlins.

Overhangs on the leeward and side edges shall have the basic zone pressure applied. Windward parapet 0 0 psf gcpn 1 5 windward roof leeward parapet 0 0 psf gcpn 1 0 overhangs 20 6 psf upward add to windward roof pressure horizontal mwfrs simple diaphragm pressures psf transverse direction normal to l interior zone. Acting on the bottom surface of the overhang in combination with pressures acting on the top surface. Qz 0 00256 kz kzt kd v2 lb ft 2 or.

The velocity pressure is depending on wind speed and topographic location of a structure as per the code standard velocity pressure q z equivalent at height z shall be calculated as. This procedure addresses roof overhangs via footnote 8 on figure 28 6 1. Mwfrs roof overhang pressures asce 7 only addresses the windward overhang specifying the use of a positive pressure coefficient of c p 0 8. Purlins c c roof pressure from 30 4 2b the effective wind pressures for zones 1 2 and 3 can be determined.

Wall 41 2 psf roof 11 7 psf.