Four fire engines and around 25 firefighters were called to a fire at an outhouse in a garden on Askwith Road in Rainham.
A single storey outbuilding and a garden shed were destroyed by the fire. There were no reports of any injuries.
The Brigade's 999 Control Officers received 18 calls about the blaze.
The Brigade was called at 1721 and the fire was under control by 1848. Fire crews from Dagenham, Hornchurch and Barking fire stations attended the scene.
The fire is believed to have started when garden waste being burnt in a metal container spread out of control.