Wind loads on permeable roofing systems

Abstract The paper presents conclusions on the critical wind loads of two different types of roofing systems: tiles on pitched roofs and paving slabs on flat roofs. Because of gaps between those roofing elements these types of roof coverings are wind permeable. The net wind load on an element is determined by the external pressure distribution on the roof surface and the internal pressure distribution underneath the roof covering. The external pressure distribution depends on the building flow field and changes in the local flow due to the shape of the roofing elements. The internal pressure distribution is influenced by the local flow direction with respect to the gaps between the elements and the resistance of the flow underneath the permeable covering. The critical loading on a roofing element does not necessarily occur for the critical external pressure distribution on the roof surface.