In plain words

Rhode Island has a statewide ADU law that every city and town must follow. An accessory dwelling unit, or ADU, is a small separate home with its own kitchen and bathroom on the same lot as a main house. Since June 2024, state law says towns must allow one ADU through a simple building permit, with no zoning hearing, in three situations. (Zoning means the local rules about what can be built where.) One: the lot is 20,000 square feet (about half an acre) or bigger. Two: the ADU fits inside the existing footprint of the house or an existing garage or shed. Three: the owner lives there and needs the unit for a family member with a disability. Outside those cases your town decides, but state limits still apply to every ADU. Towns must allow at least 900 square feet for a one-bedroom (1,200 for a two-bedroom), or 60% of the home's size if that is smaller. They cannot ask for more than one parking space per bedroom, charge higher fees than for a new house, demand extra lot area just for the ADU, or pick tenants by family ties or age. Rules from a homeowners' association (HOA) that conflict with the law are void. One firm rule: an ADU can never be rented for stays under 30 days, so short-term rentals are out. Your town's own rules still matter, and you can build only if local rules and your property allow it.

The rules at a glance

State ADU lawYes
Where the state rule appliesAll 39 Rhode Island cities and towns.
Approved without a hearing?Partly. Some ADUs or some places get staff approval; others can still need a hearing.
Kinds of ADU the state protectsinternal, attached, detached
ADUs per lot1 ADU per lot by right where the lot or building qualifies.
Owner living on siteState law doesn’t address it; your town decides.
ParkingTowns may not require more than 1 off-street parking space per ADU bedroom.
SizeTowns may cap ADU size, but the cap must allow at least 900 sq ft for a studio or one-bedroom and 1,200 sq ft for a two-bedroom, or 60% of the main home's floor area if that is smaller. Towns cannot stop an otherwise compliant ADU from having up to two bedrooms.
Lot size and setbacksFor a new ADU outside an existing footprint to be by right, the lot must be at least 20,000 sq ft. For all ADUs, setbacks and other dimensional rules cannot be stricter than those for an accessory structure in the same zone, and towns cannot require extra lot area, frontage or width just because of the ADU. An ADU inside the footprint of an existing legal nonconforming building needs no zoning relief for that existing nonconformity. Towns must allow ADUs in applications for new homes and subdivisions and cannot count them toward density limits.
FeesADU application and permit fees cannot be higher than those for a new single-family home. Towns cannot require infrastructure upgrades such as separate water or sewer lines or bigger septic capacity unless a state agency, the building code, or real capacity needs require them. Towns may waive all or part of utility assessment and tie-in fees.
Short-term rentalsBanned statewide. An ADU may not be rented for tourist or transient use, meaning stays shorter than 30 consecutive days, or listed on a hosting platform such as a short-term rental site.
Can towns opt out?No

What to do next

  1. Find your lot size and check whether the ADU would fit inside an existing building's footprint; those two facts decide whether you qualify by right.
  2. Call your town's building or zoning office and ask for its ADU ordinance and the administrative building permit process under R.I. Gen. Laws 45-24-37(e).
  3. If your lot is under 20,000 sq ft and you want a new detached unit, ask what local zoning approval is needed.
  4. If you have a septic system or private well, ask early whether a state or capacity-based upgrade will be required.
  5. Plan for long-term rental or family use only, since stays under 30 days are banned.
  6. For an attached or interior ADU, ask RIHousing or a participating lender about the FHA 203(k) loan.

Grants, loans and tax breaks

  • RIHousing FHA 203(k) loan for ADUs: RIHousing, the state housing finance agency, offers an FHA 203(k) purchase or refinance loan that can pay for adding an attached or interior ADU (such as a basement or garage unit). It does not finance detached ADUs. Work must be done by a licensed contractor within 12 months, with an FHA-approved 203(k) consultant and a short homebuyer class. Program page

What your town still decides

The state sets the by-right cases and a uniform list of limits, and towns write the rest. ADUs that do not qualify by right (for example, a new detached cottage on a lot under 20,000 sq ft) can still be allowed or regulated under local zoning, but the statewide limits on size, parking, fees and dimensions apply to every ADU application, and such an application cannot be treated as a minor or major land development project by itself. In 2024 the state deleted the old requirement that a permitted ADU be in an owner-occupied home; owner occupancy now appears only in the disability-accommodation path. No sentence in the statute forbids towns from requiring owner occupancy. By-right ADUs must be approved by administrative permit using the state criteria, which leaves little room for such a condition, but the point is untested in court, especially for ADUs that are not by right. Bills in 2025 and 2026 that would have expressly let towns require owner occupancy all failed. Towns also cannot restrict tenants by family relationship or age (except where a federal subsidy requires it), cannot require ADUs to be rented only to low- or moderate-income households outside inclusionary or comprehensive permit projects, and cannot revoke a legal ADU when the property is sold. Private HOA or condo rules that conflict with the state law are void. Each town must report ADU ordinances, permits and certificates of occupancy to the state Department of Housing by February 1 each year.

What we’re still confirming

  • The 2024 law dropped the owner-occupancy condition for by-right ADUs but doesn't say towns can't require it; ask your town how it handles this.

Laws, bills and citations

The laws behind this (2)
  • Uniform statewide standards for accessory dwelling units (P.L. 2024, ch. 284 (H 7062 Sub A) and ch. 285 (S 2998 Sub A), amending R.I. Gen. Laws ss. 45-24-31, 45-24-37 and 45-24-73 and repealing s. 45-24-74, signed June 25, 2024, in effect June 25, 2024). Makes one ADU per lot a permitted use in every residential zone, approved by an administrative building permit only, when the lot is at least 20,000 sq ft, when the ADU fits inside the footprint of an existing house or accessory building, or when it is a disability accommodation on an owner-occupied property. It also sets statewide limits on local size, parking, fee, lot and design rules for all ADUs, voids conflicting HOA and condo bans, keeps ADUs out of local building moratoria, and bans renting ADUs for stays under 30 days. Read it
  • First statewide ADU standards (P.L. 2022, ch. 437 (S 2623 Sub A) and ch. 440 (H 7942 Sub B), creating R.I. Gen. Laws ss. 45-24-73 through 45-24-76, signed June 30, 2022, in effect June 30, 2022). Barred towns that allow ADUs from imposing excessive restrictions, made an ADU a permitted use in districts with a 20,000 sq ft minimum lot size when it stayed inside an existing building's footprint, let income-restricted ADUs count as half a unit toward a town's affordable housing goal, and required towns to report ADU permits to the state each year. Most of its ADU rules were rewritten and expanded in 2024. Read it
Proposed and failed bills (5). None of these is law.
  • H 7219 (2026): died as of October 3, 2026. Would have let towns require owners of homes with ADUs to live there for at least five years, require affordable rents when tenants are not family or caretakers, and cap ADUs at 1,000 sq ft with no variance. The House committee held it for further study on March 31, 2026, and it did not advance. Bill page
  • H 7779 (2026): died as of October 3, 2026. Similar rollback bill filed for Portsmouth: five-year owner occupancy, affordable rents for non-family tenants and a 1,000 sq ft cap, at each town's option. Held for further study on March 31, 2026. Bill page
  • S 2043 (2026): died as of October 3, 2026. Would have required ADUs not occupied by family members to charge only affordable rents. Referred to the Senate Housing and Municipal Government committee in January 2026 with no further action. Bill page
  • H 8015 (2026): died as of October 3, 2026. Would have counted a long-term rental ADU as affordable housing in towns with no minimum lot size for ADUs. Held for further study on March 31, 2026. Bill page
  • S 0505 (2025): died as of October 3, 2026. Would have let towns require owner occupancy, limit ADU occupants to family members and caretakers, and cap ADUs at 800 sq ft with no variance. The Senate committee held it for further study on May 8, 2025. Bill page

Sources

  1. P.L. 2024, ch. 284 (H 7062 Sub A) and ch. 285 (S 2998 Sub A), amending R.I. Gen. Laws ss. 45-24-31, 45-24-37 and 45-24-73 and repealing s. 45-24-74 · official source
  2. P.L. 2022, ch. 437 (S 2623 Sub A) and ch. 440 (H 7942 Sub B), creating R.I. Gen. Laws ss. 45-24-73 through 45-24-76 · official source
  3. R.I. Gen. Laws s. 45-24-73 (ADU design standards and statewide treatment) · official source · checked 2026-10-03
  4. R.I. Gen. Laws s. 45-24-37 (permitted uses; ADU subsection (e)), versions effective until and after January 1, 2026 · official source · checked 2026-10-03
  5. R.I. Gen. Laws s. 45-24-31 (definitions, including ADU) · official source · checked 2026-10-03
  6. R.I. Gen. Laws s. 45-24-75 (ADUs counted toward low- and moderate-income housing) · official source · checked 2026-10-03
  7. R.I. Gen. Laws s. 45-24-76 (ADU annual reporting) · official source · checked 2026-10-03
  8. R.I. Gen. Laws s. 42-63.1-2 (definition of tourist or transient use and hosting platform) · official source · checked 2026-10-03
  9. P.L. 2024, ch. 285 (S 2998 Sub A) · official source · checked 2026-10-03
  10. P.L. 2022, ch. 437 (S 2623 Sub A) · official source · checked 2026-10-03
  11. P.L. 2026, ch. 406 (H 8004 Sub A, technical land-use amendments; does not amend s. 45-24-73) · official source · checked 2026-10-03
  12. P.L. 2026, ch. 330 (H 8005 Sub A, parking standards; does not amend s. 45-24-73) · official source · checked 2026-10-03
  13. RI General Assembly bill status system (H 7219, H 7779, H 8015, S 2043 of 2026; S 0505 of 2025) · official source · checked 2026-10-03
  14. House Municipal Government & Housing committee agenda, March 31, 2026 · official source · checked 2026-10-03
  15. 2025 S 0505 bill text · official source · checked 2026-10-03
  16. RIHousing: Accessory Dwelling Units (FHA 203(k)) · official source · checked 2026-10-03
  17. AARP Rhode Island: The ABCs of ADUs (updated 2026-09-24) · checked 2026-10-03

This is general information, not legal advice. Your town, village, city or county decides what can be built on your property. If something here looks out of date, email the team.