Wind loading data
UK wind speed map
The UK map shows Basic Mean Hourly windspeeds with the contour lines defining areas A,B,C and D. Windspeeds are shown at sea level and for every 100m increase in altitude, the Basic Mean Hourly windspeed increases by 10%, then giving the Site Mean Windspeed.
Explanation of Town Location and Country Location used in the foundation sizes table in each product Foundations and Bolting Details page/PDF
Definition of 'Town location' - Town locations are locations within built up areas, with at least 15% of the surface built on, and/or on which the average height of buildings exceed 15m - for locations on outskirts that do not comply with this, 'Country location' for foundation sizes should be used.
Definition of 'Country location' - All areas, both coastal, up to 100m ASL and inland up to 200m ASL, that are not 'Town locations' (see table for higher altitudes).
|STANDARD FOUNDATIONS||AREA A & B FOUNDATIONS UPTO 200m ASL||AREA A,B & C FOUNDATIONS UPTO 350m ASL|
|Area||Max Basic Mean Hourly Windspeed||Height above sea level for foundation design||Site mean wind speed||Actual wind velocity||Height
|Height above sea level for foundation design||Site mean wind speed||Actual wind velocity|
|A||22 m/s||100m||24.2 m/s||41.8 m/s (93 mph)||200m||26.4 m/s||45.6 m/s (102 mph)||350m||29.7 m/s||51.4 m/s (115 mph)|
|B||24 m/s||100m||26.4 m/s||45.6 m/s (102 mph)||200m||28.8 m/s||50 m/s (111 mph)||350m||32.4 m/s||56 m/s (125 mph)|
|C||25 m/s||150m||28.8 m/s||50 m/s (111 mph)||N/A||N/A||N/A||350m||33.75 m/s||58.3 m/s (130 mph)|
|D||27 m/s||250m||33.75 m/s||58.3 m/s (130 mph)||N/A||N/A||N/A||N/A||N/A||N/A|
International windspeed conversions
Our standard designs are based on a mean hourly wind speed of 28.8 m/s (metres per second).This table shows the conversion from this mean hourly wind speed, to other internationally recognised wind speed measurements. Conversions are taken from the International Code Council 'International Building Code'.
|Mean Hourly||3 Sec Gust||10 Min Average||Fastest Mile|
|28.8 m/s||43.6 m/s||30.1 m/s||34.9 m/s|
|64.4 mph||97.5 mph||67.3 mph||78 mph|
|104.4 kph||158 kph||109 kph||126 kph|
The actual wind velocity for a 28.8 m/s mean hourly wind speed = 50 m/s, 111 mph, 180 kph.