Six fire engines with 35 firefighters and officers went to the scene of a fire in a semi-detached house on The Loning in Colindale this afternoon.
All of the roof and all of the first floor of the house was gutted in the fire and a large part of the ground floor was also badly damaged.
Station Manger John Lalor said: "The crews worked very hard to minimise damage to the adjoining house.
"Fortunately no people are involved in the incident."
Fire engines from Mill Hill, Finchley, Hendon, West Hampstead , Willesden and Wembley fire stations were called at 1350. The fire was under control by 1537.
The cause of the fire is being investigated by the police and the Brigade.