Six fire engines and around 40 firefighters tackled a fire at a mid terraced house on Brookhill Close in Barnet.
Most of the first floor was damaged and the roof was destroyed by the fire. There are no reports of any injuries.
One of the Brigade's 32-metre turntable ladders was used at the scene as an observation tower to help fight the fire from above.
Control Officers took the first of four calls at 1921 and mobilised crews from Barnet, Southgate, Tottenham and Finchley fire stations to the scene. The fire was under control by 2031.
The fire is believed to have been accidental and was caused by an electrical fault in the attic.