Standards
An accessory dwelling unit may be permitted, by right, in any residential zoning district with the following limitations:
A. Accessory dwelling units are only allowed on a lot with one single-family or with a duplex dwelling as the principal dwelling and should appear to be subordinate to the principal dwelling. The ADU shall be permitted to be 900 square feet, or 60 percent of the floor area net of the principal dwelling, whichever is less, for a studio or one bedroom ADU and up to 1,200 square feet, or 60 percent of the floor area of the principal dwelling, whichever is less, for a two bedroom ADU.
B. Only one ADU may be allowed per lot by right:
1) On an owner-occupied property as a reasonable accommodation for family members with disabilities; or
2) On any lot with a total lot area of 20,000 square feet or more for which the primary use is residential; or
3) Within the existing footprint of the principal dwelling or existing secondary attached or detached structure (as of the date of the ordinance from which this chapter is derived approval) and does not expand the footprint of the structure.
C. Accessory dwelling units located within or attached to the principal dwelling shall meet all the requirements of section 82-602, District dimensional regulations, as they pertain to the principal dwelling.
D. Accessory dwelling units located in a new or existing accessory structure:
1) Shall meet the requirements of section 82-602, District dimensional regulations, and section 82-700, Miscellaneous structure and site regulations, as they pertain to an accessory structure (82-700);
2) Shall meet all applicable requirements for accessory structures in section 82-700, Accessory structures;
3) Except that in no case can an ADU be located in the front yard. ADUs are not eligible for the special permits described in section 82-700 D, Accessory structures;
E. All new or expanded detached ADUs shall have architectural detailing compatible with the main structure, including roof shape, window patterns, proportions and materials per 82-1106.1 C. All new detached ADUs shall be designed in a way that does not compete in scale or volume with the primary building mass.
F. Units located within or attached to the principal dwelling may be accessible either through the same means of ingress and egress as the principal dwelling or a separate entrance located to the side or the rear.
G. Either the principal dwelling or the ADU must be owner occupied unless both dwelling units are made available for long-term occupancy through a long-term lease (one-year or more). The owner may occupy the ADU and may only rent the principal dwelling if it is made available for long-term occupancy through a long-term lease (one year or more).
H. At least one off-street parking space will be provided in addition to the required parking spaces of the primary use.
I. ADUs shall not be offered or rented for tourist or transient use or through a hosting platform (as such terms are defined in G.L. 1956, § 42-63.1-2. as a short-term rental).
J. ADUs that meet these regulations and are not part of a larger development proposal shall be reviewed by the zoning/building official and shall not, by themselves, be reviewed as minor land developments, major land developments, or special use permits.
K. On any lot serviced with an on-site wastewater treatment system (OWTS), if the ADU results in an increase in the total number of bedrooms, the state-permitted OWTS shall meet the total bedroom demand or the owner shall have the existing or any new system approved by RIDEM.
L. The ADU will comply with all applicable state and local regulations.
M. Length of occupancy. All ADUs and accessory family dwelling units formerly granted though this chapter, if rented, must be made available for long-term occupancy through a long-term lease (one-year or more).
(Ord. of 2-3-2025(1), § 1(Exh. A))