Four fire engines and 21 firefighters and officers were called to a fire at a house in Avondale Road, Harrow.
Part of the ground floor and part of the first floor of the property were damaged by fire.
The Brigade was called at 1824 and the fire was under control at 2032. Fire crews from Stanmore, Harrow and Northolt fire stations attended the scene.
The cause of the fire is under investigation.