Four fire engines and 21 firefighters and officers dealt with a house fire on Lyham Road in Brixton this afternoon.
The fire damaged half of the roof and part of the first floor of the property.
A man left the house before the Brigade arrived. He was suffering from smoke inhalation and treated at the scene by London Ambulance Service crews.
A smoke alarm was fitted in the property and actuated.
A spokesperson for the London Fire Brigade said:
"Our advice is to have a working smoke alarm on every level of your home and the safest option is have the alarms linked together. This will give the earliest warning if there is a fire in your home."
The cause of the fire is believed to be accidental, due to an electrical fault.
The Brigade was called at 1149 and the fire was under control by 1428. Fire crews from Clapham, Brixton and Tooting fire stations were at the scene.