Eight fire engines and 58 firefighters and officers were called to a fire at a house in Wolmer Close, Edgware.
The first floor and part of the roof of a semi detached house were damaged by fire. Part of the roof of a neighbouring property was also damaged in the blaze.
The Brigade was called at 1007 and the fire was under control at 1123. Fire crews from Stanmore, Hendon, Finchley, Northolt and Wembley fire stations attended the scene.
The cause of the fire is currently unknown.