Six fire engines and 35 firefighters and officers were called to a fire at a mid-terraced house in Bradgate Road, Lewisham.
A loft conversion, which was under construction, was destroyed by the fire and most of the first floor, part of the ground floor and part of the roof were damaged. There were no reports of any injuries.
The Brigade was called at 0339 and the fire was under control at 0709. Crews remained on scene throughout the morning damping down. Fire crews from Lewisham, Forest Hill, Greenwich, Lee Green, East Greenwich and Deptford fire stations attended the scene.
The cause of the fire is under investigation.