Firefighters have spoken out about the "tragedy" of vulnerable people living in factories and outbuildings - or beds in sheds - and how they are at far greater risk of fire.
Statistics show that over the last five years there have been 438 fires in London involving buildings that should not have been occupied as a place to live, resulting in 13 fire deaths and 69 serious injuries, London Fire Brigade said.
Over the same period, the brigade has taken formal enforcement action against landlords under fire safety law around 200 times, where its fire safety officers have found people living in unsafe and unsuitable accommodation, including beds in sheds.
The lack of built-in fire safety precautions such as fire safety doors and smoke alarms and the fact that the people living in them rely on far riskier ways of cooking, heating and lighting make them potential fire traps.
To try to combat the problem, the brigade has launched the UK's first unsuitable housing toolkit, aimed at helping those working in communities across London, including firefighters, council workers, homeless charities and the police, to identify unsuitable accommodation, and those living in it, who are often the most vulnerable people in society.
"When people are forced to live in these sorts of buildings, they are at a far greater risk of having a fire as the buildings often don't contain vital safety features like fire doors and alarms, which can be the difference between life and death.
"Starting with our own staff, we are working to educate those who come into contact with unsuitable accommodation and those who live in it to try and prevent further beds in sheds fire tragedies."
Last summer a man died after a fire broke out in the outbuilding where he was living in Uxbridge, west London, which had been converted into illegal accommodation, the brigade said.
It is thought he had been living in the outbuilding, which was at the back of a row of shops, for around six years.
There were no smoke alarms and due to a broken lock, the man was unable to escape from the fire.
In April this year a woman was taken to hospital following a fire in a garage under some flats in Wandsworth, south west London.
Fire investigators believe the woman was living in the garage and that the fire was caused by a candle falling over while she was sleeping.
Housing minister Kris Hopkins said: "We are determined to root out the small minority of so-called landlords who rent dangerous, dirty and overcrowded properties without a thought for the welfare of their tenants.
"That's why we have given £6.7 million to councils to use their range of powers to confront rogue behaviour, and why we're changing the law to increase fines. Our new How to Rent guide makes tenants aware of their rental rights and puts pressure on those who are not playing by the rules."