A local authority is launching a six month probe into rooms let out but exempt from rental sector regulation.
The project is in Birmingham, where the council has received £1m from the Ministry of Housing, Communities and Local Government for extra inspectors and social workers to visit problem properties.
The council says the probe will look at an estimated 18,000 people living in “exempt accommodation” - tenants including the homeless, those with additional needs, people with mental health issues, addicts and prison leavers.
Exempt accommodation is funded by tenants through their housing benefit which is topped up to include care and support elements.
The council says landlords who let rooms under exempt status often charge two or three times the market level in exchange for providing extra 'care and support’.
A council spokeswoman says: “Supported accommodation is essential for thousands of people who rely on it to live as independently as possible. But it is essential that providers honour their commitment to deliver the right support.
“I’m really pleased that we’ve received this funding which will not only help us to champion landlords who are providing a quality service but to have the resource available to be able to effectively monitor those landlords who are not.
"The pilot in Birmingham will provide important learning to inform the scale of supported housing required and to help shape the provision in terms of quality and standards.”