A new report has found that thousands of children are growing up in shipping containers and office blocks converted into “dangerous” homes.
The Bleak Houses report by the Children's Commissioner for England estimates there could be over 210,000 children without a permanent home in England.
It warns that temporary accommodation is frequently not fit to live in and children are spending years in interim housing while they wait for an offer of permanent accommodation.
Some 124,000 youngsters are classed as officially homeless and living in temporary accommodation - plus around 90,000 in "sofa-surfing" families - but the report believes that the actual figures could be much higher due to a lack of data.
Shipping containers are being re-purposed for use as temporary accommodation, the report found, leading to cramped conditions and shifting temperatures during the seasons.
Some parents were concerned about anti-social behaviour in the surrounding areas, forcing them to keep their children inside the small units instead.
Residents living in converted container accommodation in Ealing, west London, said the units were prone to damp and mould and overheating.
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Office blocks and warehouses are also being used as temporary accommodation for families, with at least 13 office blocks in Harlow, Essex, converted into more than 1,000 individual flats.
Some units in Templefields House measure 18 square metres and are being used to house whole families, with parents and children sleeping in a single room also used as the kitchen, the report found.
Polly Neate, chief executive of housing and homelessness charity Shelter, called the analysis "damning" and said homelessness was "robbing... children of a decent childhood”.
"No child should be spending months if not years living in a converted shipping container, a dodgy old office block or an emergency B&B," she said.
"But a cocktail of punitive welfare policies, a woeful lack of social homes and wildly expensive private rents mean this is frighteningly commonplace.
"We constantly hear from struggling families forced to accept unsuitable, and sometimes downright dangerous accommodation because they have nowhere else to go.
"The devastating impact this has on a child's development and wellbeing cannot be overstated.”
Commenting on the report, Children's Commissioner Anne Longfield said: "It is a scandal that a country as prosperous as ours is leaving tens of thousands of families in temporary accommodation for long periods of time, or to sofa surf.
"It is essential that the Government invests properly in a major house-building programme and that it sets itself a formal target to reduce the number of children in temporary accommodation.”
A Government spokesperson said: "No child should ever be without a roof over their head and we are working to ensure all families have a safe place to stay.
"If anyone believes they have been placed in unsuitable accommodation, we urge them to exercise their right to request a review.
"We have invested £1.2 billion to tackle all types of homelessness, including funding a team of specialist advisers which has, in two years, helped LAs to reduce the number of families in B&B accommodation for more than six weeks by 28%."