Six fire engines and 35 firefighters and officers were called to a fire at a house in Hoylake Gardens, Mitcham.
The first floor of the semi-detached house was destroyed by fire.
The Brigade was called at 0550 and the fire was under control at 0810. Fire crews from Mitcham, Norbury, Wimbledon and West Norwood fire stations attended the scene.
The cause of the fire is under investigation.