Four fire engines and around 25 firefighters tackled a fire at a semi-detached house on Empire Road in Perivale.
Half of the first floor was damaged by the fire. Three people left the property before the arrival of the Brigade.
The Brigade was called at 0909 and the incident was over for firefighters by 1030. Firefighters from Wembley, Park Royal and Northolt fire stations are attending the scene.
The cause of the fire is under investigation.