On low-rise buildings the damage to and destructive removal of small roofing elements forming a porous roof membrane, such as tiles, shingles and shakes, is largely controlled by the heal mean andpeak wind speeds that exist just above the roof surface. Some typical high speed regions have been identified by the selective removal of cladding elements during high wind events Refs. 1 and 2. Frequently these high speed regions close to the roof surface are comer or ridge vortices. This study endeavours to map the mean surface wind speeds in the wind tunnel on some typical house geometries at a scale of 1:25 with a robust hot-probe anemometer. In one configuration these data were confirmed by full-scale measurements. Some peak wind-speed data were also collected at selected locations with a highly responsive hot-film anemometer. Both sloped and near-horizontal roofs have been investigated. In all geometries, a locally increased mean wind speed of up to sixty percent above the approach flow value was found for particular wind azimuths at critical locations on the roof surface. The peak gusts close to the roof surface varied significantly with the flow regime present, but a useful design gust factor of 2.5 times the approach mean velocity was found to be an upper bound for most roof-surface wind speeds.
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