ABSTRACT
The wind can blow rain and pollutants so that they penetrate the building. They may also erode the external fabric of the building. Wind can create differential pressures over the external surface of the building, causing either positive or negative loading. This can cause wind scour. The wind scour of gravel ballast on roofs is influenced by roof slope, wind direction, size of gravel, height and the distance stones have to travel to leave the roof surface.
