When calculating the wind load on individual structural elements such as roofs and walls, and individual cladding units and their fittings, it is essential to take account of the pressure difference between opposite faces of such elements or units. For clad structures, it is, therefore, necessary to know the internal pressure as well as the external pressure. Then the wind load, (in N), acting in a direction normal to the individual structural element or cladding unit is:
where
A = surface area of structural element or cladding unit, in m²; and
NOTES
1 If the surface design pressure varies with height, the surface areas of the structural element may be sub-divided so that the specified pressures are taken over appropriate areas.
2 Positive wind load indicates the force acting towards the structural element and negative away from it.