Eight fire engines and around 60 firefighters were called to a fire at a care home under renovation on Buntingbridge Road in Newbury Park.
Part of the ground floor of the three-storey building was damaged by the fire. There were no reports of any injuries.
Station Commander Dan Jee, who was at the scene, said: "Firefighters were faced with heavy smoke logging throughout the building when they arrived.
"Due to the location of the fire and the works which are taking place at the site, it was complex for crews to gain access to the seat of the fire."
The Brigade was called at 0147 and the fire was under control by 0544. Fire crews from Ilford, Hainault, Dagenham, Woodford and surrounding fire stations were at the scene.
The cause of the fire is under investigation by the Brigade and the Metropolitan Police Service.