ERO chief review officer Dr Graham Stoop said the school was failing to meet the requirements of the Code of Practice for the Pastoral Care of International Students in terms of ensuring all pupils under the age of 18 live in approved categories of accommodation.
The code says pupils must be accommodated in homestays, boarding establishments, with designated caregivers, in temporary accommodation (in the case of pupils on short courses only), or with their own parents.
ERO found one international pupil had been staying for some time at a homestay which was technically "temporary accommodation and unsuitable for long-term homestays".
Dr Stoop said the school was not able to show that it had a robust system for the selection of suitable homestays.
Principal Jane Johnson acknowledged an international pupil had been living in a sleepout which was situated within the property of the caregiver's house.
"When we discovered that wasn't OK, we shifted him straight away."
The school was working hard to implement procedures and processes to ensure pupil wellbeing, and that the board of trustees meets all of the Code's requirements, the principal said.
The school has international pupils from a wide variety of regions including Europe, the Middle East, Asia, and North and South America.
