Six fire engines and around 40 firefighters tackled a fire at a house converted into flats on Gloucester Drive in Finsbury Park.
A flat roof on the first floor was destroyed by fire and most of a third-floor flat roof was also damaged by the blaze. One man left the building before the Brigade arrived and was taken to hospital by London Ambulance Service crews after suffering from smoke inhalation.
The Brigade's 999 Control Officers took 40 calls to the blaze.
One of the Brigade's 32-metre turntable ladders was used at the scene as a water tower.
The Brigade was called at 1229 and the fire was under control by 1427. Fire crews from Islington, Hornsey, Kentish Town, Shoreditch, Euston and Holloway fire stations attended the scene.
The cause of the fire is under investigation.