A barbecue on a balcony could have caused a block of flats to be engulfed by fire, according to its builders.
Twenty flats with wooden balconies were destroyed and 10 more damaged in Sunday’s fire in Barking, east London.
Residents said concerns were raised with builder Bellway Homes about potential fire hazards.
A Bellway spokesman said they it was “relieved that the fire protection measures… ensured that occupants were safely evacuated”.
The London Fire Brigade said the cause of the fire was still under investigation.
Fire investigators and scientific advisers have been at the scene carrying out “extensive investigations”, the service added.
It said: “We understand that the blaze was contained to the external envelope of the eastern elevation of the building, with initial reports suggesting that it was caused by a barbecue on a resident’s balcony.”
The Metropolitan Police said 15 to 18 families were evacuated from their homes and taken to the Thames View Community Centre, about a mile from the scene.
Following an investigation by BBC Watchdog in May, Peter Mason, chair of the Barking Reach residents’ association, said he asked Bellway Homes to review the fire risk.
In an email seen by the BBC from the firm last month, Bellway said the construction method used on the development in Scotland examined by Watchdog was different and so the Barking homes in De Pass Gardens were not affected in the same way.
More than 100 firefighters tackled the Barking blaze, which spread over six floors, for more than two hours.
A Bellway spokesman said the fire was “a very serious issue” and said it was working with all parties to establish how it happened”.
He added: “Whilst we are continuing our investigations into this matter, we are supporting London Borough of Barking and Dagenham in securing alternative temporary accommodation for affected residents and are offering our support to help remediate the damaged apartments.”