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Roof Design

Wind Uplift

All roofs are subjected to the effects of wind uplift as the wind moves across them. The affects of this will depend upon a number of factors including their location, height, size, roof shape and relationship to the surrounding area. It is therefore critical that a roofing system is designed to withstand the wind loading’s that are likely to impact on the roof during its service life.  BS EN 1991-1-4:2005+A1:2010 Eurocode 1. Actions on structures. General actions. Wind actions defines the methodology to be used for the calculation of wind loads and there application.

For exposed roofing British and industry standards calculate a partial bond of bitumen, applied consistently, can resist a maximum design load of 2.4kN m2, whilst the equivalent for a full bond is taken as 3.6kN m2.  In designs with high wind load, supplementary mechanical fasteners may be required.

When mechanically fastening calculation should always be carried out site specifically, and be based upon building height, site elevation above sea level, site topography, distance from hills and urban areas, building design life and roof design. Separate calculations for different wind directions may be necessary. The effect of openings in the building such as warehouse doors must also be considered.

In inverted and ballasted roofing systems a minimum load of 80kg m2 is required above the insulation and waterproofing.

The Radmat Technical Service Department can provide these wind uplift calculation if provided with the following information: National Grid Reference or Post Code. Greatest Height(s) of roof(s)/parapet from Ground Level. Eaves Detail. Longest dimension. Roof Pitch. If Mono Pitched, Duo Pitched or Hipped.