Four fire engines and around 25 firefighters were called to a fire at a pub on Harlington Road in Uxbridge.
Part of the loft space was damaged by fire. There were no reports of any injuries.
The alarm was raised when smoke was seen coming from the roof void on the second floor. On arrival, crews carried out a search of the building and evacuated three residents on the first floor of the property. Around 20 people left the building before the Brigade arrived.
The Brigade was called at 2053 and the fire was under control by 2234. Fire crews from Hillingdon, Hayes and Heathrow fire stations attended the scene.
The fire is believed to have been accidental and caused by an electrical lighting fault in the roof void between the plasterboard and the roof tiles.