Four fire engines and around 25 firefighters were called to a fire at a house on Ascension Road in Romford.
A single-storey extension at the rear of a terraced house was destroyed by the blaze. Four people left the property before the Brigade arrived. There were no reports of any injuries.
The Brigade was called at 1707 and the fire was under control by 1754. Fire crews from Harold Hill, Dagenham, Romford and Hornchurch fire stations were at the scene.
The fire was accidental and believed to have been caused by a fault in an extractor hood.