(1) In addition to meeting all other requirements for assisted living facilities stated in this subchapter, if a secured distinct part or locked unit within a category C assisted living facility is designated for the exclusive use of residents with severe cognitive impairment, the facility must:

(a) staff the unit with direct care staff at all times there are residents in the unit;

(b) provide a separate dining area, at a ratio of 30 square feet per resident on the unit; and

(c) provide a common day or activities area, at a ratio of 30 square feet per resident on the unit. The dining area listed in (1) (b) or day rooms, sun porches and common areas accessible to all residents, may serve this purpose.