Larger buildings, possibly with expected high or transitory occupation, may have smoke shafts installed on staircores/means of escape and in such cases there is often the requirement to undertake an air leakage test to confirm that the smoke shaft leaks at no more than the design rate for the fan smoke extraction system. BAT are experienced in undertaking such Smoke Shaft Testing and often such testing can be undertaken during a building air leakage test visit with a consequent cost saving.