Seven fire engines and around 50 firefighters were called to a house fire on Queens Avenue in Feltham.
Most of a loft conversion and part of the first floor of a detached house were damaged by fire. A woman left the property before the Brigade arrived and was treated at the scene by London Ambulance crews.
Station Commander Chris Davidson, who was at the scene, said: "Crews worked incredibly hard during very challenging conditions to stop the fire from spreading.
"Once the fire was brought under control crews remained on the scene damping down any remaining hotspots."
The Brigade was called at 0802 and the fire was under control by 0930. Fire crews from Feltham, Twickenham and Richmond fire stations were at the scene.
The fire is believed to have been accidental and involved an extractor fan.