R.I. Gen. Laws § 23-27.3-105.3: Part change in use.

If a portion of a building is changed in occupancy or to a new use group, and that portion is separated from the remainder of the building with the required vertical and horizontal fire division complying with the fire grading as provided by this code, then the construction involved in the change shall be made to conform to the requirements of this code, or the requirements of the rehabilitation building and fire code for existing buildings and structures as applicable for the new use and occupancy, and the existing portion shall be made to comply with the exitway requirements of this code.