Four fire engines and around 25 firefighters tackled a fire at a metal work factory on Chase Road in Park Royal.
The internal and external extraction system of the building were damaged by fire. Six people left the property before the Brigade arrived. There were no reports of any injuries.
The Brigade was called at 1019 and the fire was under control by 1359. Fire crews from Acton, North Kensington and Ealing fire stations attended the scene.
The fire is believed to have been accidental and caused by materials igniting within the extraction system.