Four people escaped from their home as a fire ripped through a first floor bedroom.
Fire crews from Ealing were called to the blaze in 17 Royal Gardens, off Boston Road, Hanwell at 7.19pm on Sunday.
Two fire engines and 10 firefighters contained the flames, which damaged 30 per cent of the house.
Ealing watch manager Colin Bruce said the family were lucky to escape as they were all downstairs at the time of the fire.
He said: "There were no smoke alarms fitted on the upper floor and it could have been a lot worse had the fire happened later in the evening.
"We managed to save 70 per cent of the first floor and the four people escaped before the arrival of the brigade.
"They were all downstairs at the time of the fire and the crews worked hard and quickly to stop the flames spreading to the other properties within the shared accommodation parade.
"The fire could have been fatal had they been asleep upstairs where the small fire started in the bedroom."