Around 40 firefighters were called to a semi-detached house on Brookdene Road soon after 4pm yesterday (July 27).
One person was treated on the scene by the London Ambulance Service.
A single-storey lean-to was destroyed in the flames and the outside of the house and its windows were damaged.
36 reports of the fire were made in total before it was brought under control by 5.30pm.
The fire is believed to have been accidental and caused by an electrical fault.
An LFB spokesperson said: “Six fire engines and around 40 firefighters tackled a fire at a semi-detached house on Brookdene Road in Lewisham.
“A single storey lean to was destroyed by the fire.
“Part of the external fascia on the second floor and a small part of an external window on the first floor were damaged by the fire.
“Part of the roof, first floor external fascia and a small part of the ground floor of a second semi-detached house were also damaged by the fire.
“One person was treated on scene by London Ambulance Service.
“One of the Brigade’s 32-metre turntable ladders was used at the scene as an observation tower to provide the Incident Commander with an aerial view of the fire.
“Control Officers took the first of 36 calls at 1611 (25/07) and mobilised crews from Erith, Bexley, East Greenwich and surrounding fire stations to the scene.
“The incident was over for firefighters at 1727.
“The fire is believed to have been accidental and was caused by an electrical fault.”
