The fire destroyed a single-story vehicle workshop and damaged a portion of a second workshop. One man left the building before crews arrived and was treated on the scene by London Ambulance Service crews for smoke inhalation.
As a precaution, firefighters removed one gas cylinder and cooled it, as some cylinders can explode when exposed to heat.
The Brigade was called about the fire at 5.42pm and was under control by 8.15pm. Firefighters from Romford, Harold Hill, Hainault, Dagenham, and other nearby stations responded.
The fire is thought to have started accidentally.
