Four fire engines and around 25 firefighters were called to a house fire on Harrow View in Harrow.
Part of the first floor and loft conversion was damaged by fire. There were no reports of any injuries.
Harrow View was temporarily closed to traffic whilst the incident was ongoing.
The Brigade received the first of nine calls at 1538 and crews from Harrow, Northolt and Stanmore fire stations attended the scene along with a 32-metre turntable ladder. The fire was extinguished by 1703.
The cause of the fire has been recorded as accidental.