ADU rules in North Kingstown

North Kingstown's own text allows an ADU only inside the principal dwelling or an existing accessory structure (Sec. 21-22 definition), and only by special use permit from the zoning board in the RR, PP, NR, VR, PV, VLDR and LDR residential districts (Article III, use 6; prohibited in MF). A brand-new detached cottage is therefore not an ADU under the local definition. State law overrides this for qualifying lots: R.I. Gen. Laws 45-24-37(e) and 45-24-73(a) make one ADU per lot permitted by right, through an administrative building permit, on any residential lot of 20,000 sq ft or more, within an existing structure's footprint, or as a disability accommodation. Because every residential district's single-family minimum lot area is 20,000 sq ft or more (Article IV), nearly every conforming lot qualifies under the state's 20,000 sq ft circumstance; smaller nonconforming lots fall back to the local special use permit route. Under the Rhode Island directory convention this is recorded as conditional because the only by-right path is the statutory one.

Locally, an ADU within the principal dwelling needs a special use permit from the zoning board in every residential district except MF, where it is prohibited (Article III, use 6), and the building must keep the appearance of a single-family residence, with new entrances on the side or rear and enclosed stairways (Sec. 21-325(7)a.8). State law makes an internal conversion that does not expand the footprint, or any ADU on a residential lot of 20,000 sq ft or more, permitted by right through an administrative building permit (45-24-37(e), 45-24-73(a)(2) and (3)). A footprint-expanding addition on a lot under 20,000 sq ft still needs the local special use permit.

Sec. 21-325(7)a.10 caps the ADU at 40 percent of the principal dwelling's gross floor area (excluding parking areas) or 1,000 sq ft, whichever is less, and a.3 allows at most two bedrooms. The 40 percent figure falls below the state floor: 45-24-73(b)(1) requires towns to allow at least 900 sq ft or 60 percent of the principal dwelling's floor area (whichever is less) for a studio or one-bedroom ADU, and 1,200 sq ft or 60 percent for a two-bedroom ADU. For a 2,000 sq ft house the local cap is 800 sq ft while the state floor is 1,200 sq ft for one or two bedrooms. The zoning board has heard dimensional variance requests to exceed the local size limit citing 45-24-73 (notices of 12-10-2024 and 1-28-2025), so the local cap is still applied in practice.

Locally the requirement is ongoing: Sec. 21-325(7)a.7 says the owner must continue to occupy one of the two units as a residence, a.6 requires both units to stay in the same ownership with a deed restriction recorded before the certificate of occupancy, and the Sec. 21-22 definition places ADUs on an 'owner-occupied lot'. State law requires owner occupancy only for the disability-accommodation ADU under 45-24-73(a)(1) and does not list owner occupancy among the rules towns may not impose, so the local rule is recorded as written. However, 45-24-73(b)(2)(xii) bars a town from revoking a legally established ADU's permitted status on transfer of title or occupancy, which limits how the ongoing requirement can be enforced against ADUs built by right under (a)(2) or (a)(3).

Sec. 21-325(7)a.4 requires at least one additional off-street parking space on the lot for the ADU, paved or all-weather gravel, and allows no more than two outdoor spaces for the new ADU. State law bars requiring more than one off-street space per ADU bedroom (45-24-73(b)(2)(viii)); the local one-space minimum fits that cap for a one- or two-bedroom unit, though its application to a studio is untested.

The local ordinance routes every ADU through a zoning board special use permit (Article III, use 6, 'S'; Sec. 21-325(7)a.11 lists the site plan, floor plans, elevations and parking plan the special use permit application needs), with planning commission development plan review added in business districts within the groundwater overlay (a.5). State law overrides that for ADUs meeting 45-24-73(a), on a residential lot of 20,000 sq ft or more, within an existing footprint, or as a disability accommodation, which must be permitted 'through an administrative building permit process only' (45-24-37(e)). In practice that covers most conforming residential lots; ADUs outside those circumstances still need the special use permit hearing.

R.I. Gen. Laws 45-24-73(b)(8) bars offering or renting any ADU for tourist or transient use (under 30 consecutive days) or through a hosting platform, so an ADU may only be rented long term. The town's zoning text sets no tenant restriction beyond the ongoing owner-occupancy and same-ownership deed restriction (Sec. 21-325(7)a.6 and a.7), which also prevents selling the ADU separately. For other dwellings, Chapter 9, Article XVIII requires short-term rentals (under 30 consecutive days) to register with the state and with the town clerk each calendar year for a $100 fee (Secs. 9-415 to 9-419), but that registration does not open ADUs to short-term rental.