Four fire engines and around 25 firefighters were called to a fire at a house on Longland Drive in Whetstone.
Part of the ground floor and the loft conversion of a detached house under renovation was damaged by fire. There were no reports of any injuries.
Sub Officer Andy Thornton, who was at the scene, said: "On arrival, crews could see the fire through the windows of the house. Smoke was going out towards the rear garden where the back of the building was exposed due to renovation works.
"Firefighters made their way into the property to bring the fire under control. Thankfully, there was no one inside the house at the time."
The Brigade was called at 2317 and the fire was under control by 0143. Fire crews from Barnet, Finchley and Mill Hill fire stations attended the scene.
The cause of the fire is under investigation by the Brigade and the Metropolitan Police Service.