Tenants found living in an illegal bungalow in Cambridge had to cook in a makeshift kitchen that had a toilet in the middle, a council has said.
The landlord has been given eight months by Cambridge City Council to demolish the building, which was built at the back of his house.
The council had been told it would be used as a music room or summer house.
The landlord was unavailable for comment.
Planning officers were made aware of the bungalow being built on the site of a disused garage in August last year.
After a visit in June, the authority said it had "all the facilities for day-to-day living" with "no physical or functional connection" to the main house, and this breached planning regulations.
A later inspection then found the kitchen had been moved to an outbuilding, which was also a toilet.
The council said if the bungalow was lawfully constructed for "incidental" use - such as a music room - then planning permission could have been obtained to turn it into accommodation at a later point.
But the council said the bungalow needed planning permission and "previous applications for similar schemes have been refused and dismissed on appeal".
An enforcement notice has been issued to the owner giving him eight months to knock the bungalow down.
The outbuilding has since been turned into a laundry room, the council said.