Eight fire engines and around 60 firefighters were called to a fire at a house in Wingford Road in Streatham Hill.
All of the first floor and roof of the property were destroyed by fire.
The Brigade was called at 1314 and the fire was under control at 1601. Fire crews from Brixton, Clapham, West Norwood, Tooting, Lambeth and Battersea fire stations attended the scene.
The cause of the fire is believed to be accidental.