A family with a six-year-old child were found living in a converted garage with no heating in Leicestershire, but have been moved to a new home in time for Christmas.
The detached double garage had undergone a partial conversion and was equipped with a small kitchen, bathroom and a bed-sitting room, according to Blaby District Council.
But officers inspecting the property found there to be no heating, inadequate insulation and no smoke alarms. The windows and doors were also rotten.
On a later visit they found a fault with the electrics, with the shower having stopped working as a result, and only one working plug socket.
Environmental health officer for Blaby District Council, Phil Fasham told the BBC: "For a property for people to live in, it's one of the worst I have seen because it was so tiny."
The Portuguese family had been living in the property in Braunstone Town for seven months before reporting the substandard conditions to local authorities and had been paying as much as £400 a month in rent.
One of the gravest concerns to officers was the main garage door, which had not been removed by the landlord.
With the door in place, tenants had nowhere to sit with natural light and a fire in the property could have left them trapped with no window to escape through, the council said.
Environmental health served a prohibition order on the property, which ensures that the landlord will be prosecuted if anyone lives in it before extensive works are completed to convert to standards approved by the council.
Councillor Guy Jackson, who looks after neighbourhood and environmental services, said: "There are a lot of laws covering rented properties and it can be hard for landlords to keep up to date with changes such as the new requirement for having smoke alarms fitted on every floor.
"It is hard to believe, however, that any landlord thinks that it is acceptable to let a family live in the conditions found in this property.
"I hope the strong action taken by Blaby District Council will deter other landlords from letting tenants live in poor conditions."