Four fire engines and around 25 firefighters were called to a fire at a flat above a shop and garage in King Street, Hammersmith.
A roof terrace was destroyed by fire and part of a flat on the second floor was damaged by fire. One man left the building before the arrival of the Brigade and was treated at the scene for smoke inhalation.
The Brigade's 999 control officers took 38 calls to the fire.
The Brigade was called at 1319 and the fire was under control at 1411. Fire crews from Hammersmith, Fulham and Chiswick fire stations attended the scene.
The cause of the fire is believed to be accidental and due to an electrical or mechanical failure within an air conditioning unit.