Four fire engines and around 25 firefighters were called to a house fire on Priors Gardens in Ruislip.
Most of the first floor and half of the roof of a semi-detached house were damaged by fire. There were no reports of any injuries.
The Brigade was called at 2157 and the fire was under control by 2301. Fire crews from Northolt, Harrow and Hillingdon fire stations attended the scene.
The cause of the fire has been recorded as undetermined.