ADU rules in Providence

One ADU per lot is permitted by right in all residential districts (R-1A, R-1, R-3, R-4 and R-P under §300.A), and it may be placed in a permitted outbuilding or in a detached garage, so a detached backyard unit is allowed without the state's 20,000 sq ft lot or existing-footprint gates. Chapter 2024-69 (approved December 9, 2024) rewrote the rules to comply with the 2024 state act and deleted the former bans on kitchens and sleeping areas in outbuildings and detached garages. Only one detached garage is allowed per lot; outbuildings are barred from front and corner side yards and must sit at least 3 feet from lot lines, while detached garages need no side or rear setback. Under the Rhode Island directory convention a 'yes' means the local ordinance allows this form by right in every residential district beyond the statutory floor of R.I. Gen. Laws 45-24-37(e) and 45-24-73(a).

An ADU 'may be located within the principal structure' in every residential district by right, on single-, two-, three- or multi-family lots (§201 definition). The city's October 2025 ADU guidelines recognize two forms: a 'Separate ADU' (no internal connection; may be in the existing house, in an addition to it, or in an accessory structure) and an 'Internal ADU' internally connected to the principal unit, which the building code reviews as an interior renovation of the existing unit but zoning still counts as an ADU.

§1302.U(3) caps an ADU at 'whichever is less': 60 percent of the principal dwelling's gross floor area, or 900 sq ft GFA for a studio or one-bedroom, or 1,200 sq ft GFA for a two-bedroom, and no ADU may have more than two bedrooms. That is exactly the statutory minimum allowance of R.I. Gen. Laws 45-24-73(b)(1), so the cap meets the state floor and no more. A detached ADU in an outbuilding or detached garage also follows the accessory-structure rules: height of 10 feet at the lot line plus one foot per foot of additional setback up to 20 feet and two stories (§1302.A(6)), and it counts toward the district's building and impervious coverage limits (§1302.A(5)). The city's ADU guidelines state only the 900/1,200 sq ft figures, but the code's 60 percent qualifier still applies to small houses.

The current ordinance contains no owner-occupancy requirement for an ADU. Chapter 2024-69 deleted the old §1200.E(1) accessory-unit entitlement 'in an owner-occupied residence' (now 'Reserved') and the §1204 use definition tied to an 'owner-occupied' dwelling; neither survives in the compilation through Ord. 2026-35. The only owner-occupancy rule nearby is for short-term rentals of houses in the R-1A, R-1, R-3 and R-4 districts (§1202.L(6)(a)), which does not reach ADUs because ADUs may not be short-term rented at all.

§1410.B(9) lists 'Accessory dwelling units' among the exemptions from off-street parking requirements, so no space is required for the ADU. This is stricter in the homeowner's favor than the state cap of one space per ADU bedroom (R.I. Gen. Laws 45-24-73(b)(2)(viii)). Parking for the principal dwelling is unaffected.

§1302.U makes one ADU per lot 'permitted in all residential districts' with no special use permit or Plan Commission review, so ADUs go through the Department of Inspection and Standards' building permit, and the city's guidelines say a Certificate of Occupancy is required for every ADU (it may be applied for with the building permit). Accessory structures require a building permit (§1302.A(8)). This matches R.I. Gen. Laws 45-24-37(e), which requires an administrative building permit process for ADUs within the statutory circumstances. Exterior work in a Historic District Overlay also needs a Historic District Commission certificate of appropriateness (§1911), which staff may issue for some work but only the commission can deny.

R.I. Gen. Laws 45-24-73(b)(8) bars renting any ADU for tourist or transient use (stays under 30 days) or through a hosting platform, and Providence's §1302.U(6) says the same: 'Short-term rentals are not permitted within accessory dwelling units' (the ordinance defines a short-term rental as occupancy for a fee for fewer than 30 consecutive days). Long-term rental is allowed, and the city's guidelines confirm tenants may not be restricted by family relationship or age. For other housing, Providence licenses short-term rentals through an annual $50 temporary use permit and requires owner occupancy in the R-1A, R-1, R-3 and R-4 districts (§1202.K(6), §1202.L(6)), but that permit is not available for an ADU. Neither the code nor the state law requires the ADU to stay under common ownership, and 45-24-73(b)(2)(xii) bars revoking a legal ADU on transfer of title.