Firefighters have issued a reminder of their smoking safety advice following a fire at a terraced house on Huddleston Road in Kentish Town.
The roof void between the ground and first floors was destroyed by the fire. There are no reports of any injuries.
The fire is believed to have been accidental and was caused by the unsafe disposal of smoking materials.
A London Fire Brigade spokesperson said: "If you smoke it is vitally important you stub it right out, preferably in an ashtray.
"Always ensure your cigarette is completely out when you’ve finished smoking it. If you don’t, you risk causing a fire as you don’t know what it may land on which could potentially start a fire."
Control Officers received the call at 1900 and mobilised four fire engines and around 25 firefighters to the scene from Kentish Town, Holloway and Hornsey fire stations. The incident was over for firefighters at 2101.