Six fire engines and around 40 firefighters tackled a fire at a house under renovation on Finchley Road in Golders Green.
Most of the first floor and roof of the two-storey semi-detached house was damaged by fire. Around 10 people left a neighbouring property before firefighters arrived. There have been no reports of any injuries.
Road closures were put in place to allow crews to work safely with people asked to avoid the area.
The Brigade's 999 Control Officers received 26 calls about the fire.
The Brigade was called at 1919 and the fire was under control by 2115. Crews from West Hampstead, Hendon, Soho, Tottenham and surrounding fire stations attended the scene.
The cause of the fire is under investigation by the Brigade and Metropolitan Police.