Seven people were led to safety by firefighters following a blaze in Kenninghall Road, Stoke Newington.
Four fire engines and around 20 firefighters tackled the fire. Part of a two-roomed loft conversion was damaged.
One woman was treated on the scene for smoke inhalation.
Unfortunately, there was no working smoke alarm in the property.
A London Fire Brigade spokesperson said: “Homes need multiple smoke alarms or you won’t be properly covered. Ideal spots for smoke alarms include rooms where you leave electrical equipment running like satellite boxes, computers or heaters; any room where you smoke, and anywhere you charge your mobile or laptop.
“As a minimum you should have smoke alarms on every floor - in the hallways and the rooms you use the most, plus a heat alarm in the kitchen. They should be tested regularly."
The Brigade was called at 0259 and the fire was under control by 0408.
Crews from Stoke Newington, Homerton and Bethnal Green Fire Stations attended the incident.
The cause of the fire is under investigation.