Six fire engines and around 40 firefighters tackled a maisonette fire on West End Road in Ruislip.
The two-storey property was mostly damaged by fire, and the roof was destroyed by fire. A roof of an adjoining property was partially damaged by fire. Seven people left the property before the arrival of the Brigade, and there were no injuries reported.
The Brigade was called at 1658 and the fire was under control by 1823. Crews from Ruislip, Hillingdon, Southall and surrounding fire stations attended the scene.
The cause of the fire is under investigation.