New reports have warned that a lack of regulation means people in 24-hour mental health residences are at risk of abuse and substandard living conditions and treatment.
That is according to the Mental Health Commission, which has published inspection reports into 43 of the country's supervised residences.
It found "serious deficiencies" in many of the 24-hour nurse supervised facilities.
In 14% of those inspected, doors were locked and residents were not free to leave.
In 77% of them, residents were unable to lock their bedroom doors.
The reports also found that there was no access to a kitchen to make tea, coffee or snacks in 44% of the units.
Some 58% of them had more than 10 beds - the maximum number of beds recommended.
Two of the residences had bedrooms which catered for four people.
Only 44% of residences were in good physical condition and 19% required urgent maintenance and refurbishment.
The report found that just 59% of the residences offered residents single room accommodation.
In those with shared rooms, 58% had no privacy between beds or within the bedrooms.
Initially facilitating service users who had been long-stay residents in psychiatric hospitals, these 24-hour supervised residences now also accommodate people who have been discharged from both long-stay and acute mental health care services.
This is the first publication of inspection reports and is part of a three-year programme which will see the inspection of all 24-hour residences.
Dr Susan Finnerty, inspector of mental health services, said: "It is concerning that some of our most vulnerable citizens, many of whom have spent decades in psychiatric hospitals, are now being accommodated in unregulated, poorly maintained residences, that are too big, are institutionalised, restrictive and are not respectful of their privacy, dignity and autonomy."
John Saunders, chairman of the Mental Health Commission, added: "Ideally, there should be a 'care pathway', where people move from hospital to highly supported accommodation, graduating to more independent settings as they gain skills and confidence.
"However, at present, there is a serious lack of provision of suitable accommodation options, and rehabilitation and recovery staff to enable service users to move through the different stages of recovery and progress towards the goal of independent community-based living, and many people have to remain in highly supported accommodation.
"The Commission has consistently called for the regulation of 24-hour nurse supervised residences and the findings of these inspections demonstrate the necessity of regulation. We are calling for the government to take action in this regard".