Straight answers
Can you put a tiny house in your backyard in Rhode Island?
Yes, when it is permitted as an accessory dwelling unit on a foundation. Since 25 June 2024, R.I. Gen. Laws 45-24-73(a) has made one ADU per lot allowed by right in three circumstances: on an owner-occupied property as a reasonable accommodation for family members with disabilities; on a lot with a total lot area of 20,000 square feet or more whose primary use is residential; or where the unit sits within the existing footprint of the primary structure or an existing accessory structure, attached or detached, without expanding it. Only the first of the three requires anyone to live on the property. Section 45-24-37(e) then makes an ADU that meets those requirements a permitted use in all residential zoning districts, permitted through an administrative building permit process only, so a qualifying backyard unit does not go to a zoning hearing. A home on wheels is a separate question, because Rhode Island's vehicle definitions treat that as recreational.
Figures verified against the sources below · October 13, 2026
01 — The longer answer
What the statute guarantees, and what still decides your lot
The three by-right routes, and which one asks you to live there
This is where most summaries of the Rhode Island law go wrong, including an earlier version of our own state guide. The owner-occupancy condition belongs to one route, not all three. R.I. Gen. Laws 45-24-73(a) allows one ADU per lot by right: on an owner-occupied property as a reasonable accommodation for family members with disabilities; or on a lot with a total lot area of 20,000 square feet or more for which the primary use is residential; or where the proposed ADU is within the existing footprint of the primary structure or an existing accessory attached or detached structure and does not expand that footprint. The second and third routes say nothing about who lives on the property. The lot-area figure is also written as 20,000 square feet or more, not more than 20,000, so a lot of exactly that size qualifies. For a new detached building in the yard the lot-area route is usually the operative one, and at a little under half an acre it is a real threshold in a state with Rhode Island's lot sizes.
A permitted use in every residential district, by building permit alone
The route matters as much as the right. Section 45-24-37(e) says that notwithstanding any other provision of the zoning enabling chapter, an ADU meeting the requirements of 45-24-31 and 45-24-73(a) shall be a permitted use in all residential zoning districts, and shall be permitted through an administrative building permit process only. A permitted use is not a special-use permit or a variance, and an administrative process is not a hearing. Section 45-24-73(b)(3) adds that an ADU application which is not allowed by right under the section shall not, by itself, be reviewed as a minor or major land development project. Taken together, the design review a backyard unit faces in Rhode Island is a building permit, and the arguing that used to happen at a zoning board is meant to be gone.
The size your city or town has to allow
The statute does not set a maximum size. It sets a floor underneath whatever maximum a municipality chooses, which is the opposite of how these figures are usually reported. Under 45-24-73(b)(1) a municipality may establish a maximum unit size, but the limitation must allow, subject to applicable dimensional requirements, a studio or one-bedroom ADU of at least 900 square feet or 60 percent of the floor area of the principal dwelling, whichever is less, and a two-bedroom ADU of at least 1,200 square feet or 60 percent of the principal dwelling, whichever is less. So on a 1,400 square foot house the protected figure for a one-bedroom unit is 840 square feet, because 60 percent is the lesser of the two. Read any town's published cap against that floor rather than the other way round. The section separately bars a municipality from prohibiting an ADU that otherwise complies from having up to two bedrooms.
Twelve things a municipality cannot do
Section 45-24-73(b)(2) is a list, and it is the most useful part of the law to have read before a counter conversation. For all ADU applications a municipality shall not: restrict tenants by familial relationship or age, unless needed to comply with a federal affordability subsidy; charge application or permitting fees above those for a new single-family dwelling; require infrastructure improvements, including separate water or sewer service lines or expanded septic capacity, unless a state agency requires them under state law or regulation, or the building code does, or they are needed to address capacity for the ADU; discriminate against groups protected by fair housing law; impose dimensional requirements or development standards that exceed those for an accessory structure in the same zoning district; require additional lot area, frontage or width on a conforming or legal nonconforming lot solely to accommodate an ADU; require zoning relief for a unit inside the existing footprint of a legal nonconforming structure to address the existing nonconformity; require more than one off-street parking space per bedroom; limit ADUs to lots with preexisting dwellings, or prohibit them as part of applications for new primary dwellings or subdivisions; prohibit up to two bedrooms; require low- or moderate-income occupancy outside an inclusionary or comprehensive permit application; or revoke the permitted status of a legally established ADU, or require it to be disassembled, when the property changes hands or occupancy.
What actually changed in June 2024
The 2024 act is worth understanding because it is the reason older guidance reads so differently. Rhode Island first put ADU standards in 45-24-73 in 2022, and that version opened with the words any municipality that chooses to permit accessory dwelling units, then listed restrictions such a municipality could not impose. Permitting them at all was the town's choice. H 7062 Substitute A, enacted 25 June 2024 as P.L. 2024 ch. 284, struck that opening and replaced it with the by-right language, added the 900 and 1,200 square foot floors, extended the list of prohibitions, and rewrote 45-24-37(e) into the permitted-use and administrative-permit rule. The statute's own history note on the General Assembly's site ends at P.L. 2024 ch. 284 and ch. 285, so nothing in the 2025 session changed it. Anything written before mid-2024 describes a permissive regime that no longer exists.
The building code: the 2021 IRC, with the tiny house appendix in force
Rhode Island runs one residential code statewide, and the edition is newer than most state-by-state tables say. RISBC-2, the Rhode Island State One and Two Family Dwellings code at 510-RICR-00-00-2, adopts the International Residential Code 2021 edition together with the Rhode Island amendments in the regulation, and it is an active rule effective 1 December 2025. The detail that matters for a small home is the appendix list: the regulation adopts appendices AE, AH, AK, AM, AO, AQ, AR, AS and AW, and deletes all others. AQ is the tiny house appendix in the 2021 edition, the one that makes a loft, a ladder and reduced headroom buildable to code rather than treated as an undersized house. A good many states leave it out. Rhode Island has it, statewide, without a town having to adopt anything.
Snow, wind and frost are printed in the code, municipality by municipality
You do not have to ask a building department for the design figures in Rhode Island, which is unusual. Section 2.4 of RISBC-2 is a table of ground snow load, flat roof snow load, four basic wind speeds and frost depth for each of the state's 39 municipalities. Frost depth is 3 feet 4 inches everywhere except New Shoreham on Block Island, which is 2 feet 6 inches. Ground snow load runs from 25 pounds per square foot on Block Island to 40 in the northwest towns, and flat roof snow load is 30 everywhere except New Shoreham at 25. The wind columns are one per risk category, and for Risk Category II the table gives Providence 125 mph, Newport 131, New Shoreham 134 and Burrillville 121. Which risk category a particular building falls in is set by the code, so confirm that with the building official rather than assuming. Two footnotes carry the coastal consequence: a hash marks a wind-borne debris region above 130 mph within a mile of the mean high coastal water line, and an asterisk marks areas at 140 mph or more.
On an unsewered lot, septic is the constraint, not zoning
This is the gap the zoning statute deliberately leaves open. A municipality may not require expanded septic capacity for an ADU, but that prohibition carries an exception where a state agency requires it under state law or regulation, and the Department of Environmental Management's onsite wastewater rules are exactly that. Under 250-RICR-150-10-6, section 6.22(B), a single family residence is designed at 115 gallons per day per bedroom, two persons per bedroom, with a minimum residential design flow of 345 gallons per day, which the table equates to three bedrooms, unless otherwise permitted under 6.22(D). Section 6.45(A) then caps design flow at 345 gallons per day per 20,000 square feet of the applicant's lot area for new building construction and for alterations to a structure, where the property or any adjacent lot is served by an onsite drinking water well, public or private, or where any drinking water well sits within 200 feet of the proposed system. The rule's own gloss is that this works out to roughly one sixth of an acre of lot area per bedroom. So on a well-and-septic lot the bedroom count of the new unit, not the zoning, is often what decides whether it fits.
Within 200 feet of a coastal feature, the CRMC has a say too
Rhode Island is small and almost entirely coastal, so this reaches a lot of back yards. R.I. Gen. Laws 46-23-6(2)(iii) limits the Coastal Resources Management Council's authority over land above the mean high water mark to 200 feet from the coastal physiographic feature, or to what is needed to carry out resources management programmes, and limits it further to situations where there is a reasonable probability of conflict with a resources management plan or damage to the coastal environment. That is a boundary, not a ban, and it is narrower than it is often described. What it means practically is that the distance from the nearest coastal feature is a question worth answering early, alongside the flood zone, because on a coastal parcel those two usually shape the foundation and the envelope more than snow does.
On wheels: Rhode Island's categories are recreational by definition
Rhode Island's vehicle law has no tiny house category, and the categories it does have are defined as recreational. Under 31-1-3(f) a camping recreational vehicle is a vehicular type camping unit certified by the manufacturer as complying with ANSI A119.2, designed primarily as temporary living quarters for recreation; the basic units listed are tent trailers, fifth-wheel trailers, motorized campers, travel trailers and pick-up campers. A travel trailer at 31-1-3(gg) is a towable recreational vehicle not exceeding 320 square feet. A park trailer at 31-1-3(x) is a camping recreational vehicle on a single chassis mounted on wheels, certified by the manufacturer to ANSI A119.5. None of those is the ADU route. An ADU under 45-24-31(2) is a residential living unit on the same lot as a legally established dwelling, providing complete independent living facilities, and 45-24-37(e) permits it through a building permit, which means the building code. If the plan is a backyard home someone lives in year-round, the unit on a foundation is the route the statute protects. Whether any particular town permits a recreational vehicle as a dwelling is a local question we did not research.
No short-term rental, and a homeowners association cannot override it
Two provisions decide arguments that come up after the unit is built. Section 45-24-73(b)(8) says ADUs shall not be offered or rented for tourist or transient use, or through a hosting platform, using the definitions in 42-63.1-2. So the by-right unit is for living in, not for letting by the night. Pointing the other way, 45-24-73(b)(6) makes private restrictions on ADUs imposed by condominium associations, homeowner associations or similar bodies void as against public policy where they conflict with the section or with the statutory definition of an ADU. Section 45-24-73(b)(7) adds that ADU development may not be restricted by a locally adopted ordinance or policy placing a limit or moratorium on residential units in land zoned for residential use, and (b)(4) stops a municipality counting ADUs toward the density of a larger development proposal.
The honest summary is that Rhode Island is now one of the more straightforward states for a backyard home, and the remaining work is on the lot rather than at the counter. The right is statutory, the approval is a building permit, the code is the 2021 IRC with the tiny house appendix in force, and the design figures are published per municipality. What is left to establish for a specific address is the lot area against the 20,000 square foot route, whether the property is sewered or on a well and septic, and the distance to the nearest coastal feature and the flood zone. Factory-built approval is a separate question in every state, so ask any manufacturer, ours included, how a unit would be approved for your address before ordering.
03 — Sources
Each figure above links to the authority it came from.
R.I. Gen. Laws 45-24-73(a): pursuant to 45-24-37, one accessory dwelling unit per lot shall be allowed by right (1) on an owner-occupied property as a reasonable accommodation for family members with disabilities; or (2) on a lot with a total lot area of twenty thousand square feet (20,000 sq. ft.) or more for which the primary use is residential; or (3) where the proposed ADU is located within the existing footprint of the primary structure or existing accessory attached or detached structure and does not expand the footprint of the structure. 45-24-73(b)(1): a municipality may establish a maximum unit size but the limitation must allow a studio or one bedroom ADU of at least nine hundred square feet, or sixty percent of the floor area of the principal dwelling, whichever is less, and a two-bedroom ADU of at least twelve hundred square feet, or sixty percent, whichever is less. 45-24-73(b)(2): the twelve things a municipality shall not do, including requiring infrastructure improvements unless required by a state agency under state law or regulation, by the building code, or to address capacity for the ADU, and requiring more than one off-street parking space per bedroom. 45-24-73(b)(3), (4), (6), (7) and (8): review as a land development project, density counting, private covenants void as against public policy, local moratoria, and no tourist or transient use. History of Section ends at P.L. 2024, ch. 284 and ch. 285, effective June 25, 2024
webserver.rilegislature.govR.I. Gen. Laws 45-24-37(e): notwithstanding any other provision of this chapter, an accessory dwelling unit that meets the requirements of 45-24-31 and 45-24-73(a) shall be a permitted use in all residential zoning districts, and shall be permitted through an administrative building permit process only
webserver.rilegislature.govR.I. Gen. Laws 45-24-31(2): an accessory dwelling unit is a residential living unit on the same lot where the principal use is a legally established single-family dwelling unit or multi-family dwelling unit, providing complete independent living facilities for one or more persons, which may take various forms including a detached unit, a unit that is part of an accessory structure such as a detached garage, or a unit that is part of an expanded or remodeled primary dwelling
webserver.rilegislature.govP.L. 2024, ch. 284 (H 7062 Substitute A, enacted 06/25/2024), showing the amendment: the 2022 text of 45-24-73(a) opened "Any municipality that chooses to permit accessory dwelling units (ADUs) within the municipality, shall not impose any excessive restrictions" and was struck and replaced with the by-right language, the 900 and 1,200 square foot size floors were added, and 45-24-37(e) was rewritten from an accommodation limited to family members with disabilities or persons sixty-two years or older into the permitted-use and administrative-building-permit rule
webserver.rilegislature.govRISBC-2 Rhode Island State One and Two Family Dwellings, 510-RICR-00-00-2, ACTIVE RULE effective 12/01/2025. Section 2.2: the Building Code Standards Committee adopts and incorporates as the Rhode Island One & Two-Family Dwelling Code the provisions of the International Residential Code (IRC), 2021 edition, not including any further editions or amendments, to the extent not inconsistent with R.I. Gen. Laws Chapter 23-27.3 and the provisions reserved, deleted or amended in the regulation. Appendices to IRC 2021: "The following Appendices are adopted: AE, AH, AK, AM, AO, AQ, AR, AS and AW. All other Appendices are deleted." Section 2.4, Rhode Island Snow Load, Wind Speed and Frost Depth Table, covering all 39 municipalities: frost depth 3'-4" except New Shoreham 2'-6"; ground snow load 25 psf (New Shoreham) to 40 psf; flat roof snow load 30 psf except New Shoreham 25; Risk Category II basic wind speed Providence 125, Newport 131, New Shoreham 134, Burrillville 121 mph; notes defining the wind-borne debris markers at above 130 mph within a mile of the mean high coastal water line and at 140 mph or greater
rules.sos.ri.govRhode Island DEM, Rules Establishing Minimum Standards Relating to Location, Design, Construction and Maintenance of Onsite Wastewater Treatment Systems, 250-RICR-150-10-6, ACTIVE RULE effective 07/01/2022. Section 6.22(B) Wastewater Design Flows: single family residence 115 gallons per day per bedroom (2 persons per bedroom), with the bracketed note that the minimum design flow for residential use shall be 345 gallons per day (three bedrooms) unless otherwise permitted under 6.22(D). Section 6.45(A) Nitrogen Loading in Areas of Onsite Drinking Water Wells: for all applications for New Building Construction and for Alterations to a Structure the design flow shall not exceed 345 gallons per day per 20,000 square feet of applicant's lot area where the property utilizing the OWTS or any adjacent lot is served by an onsite drinking water well (public or private), or if there is a drinking water well within 200 feet of the proposed OWTS, except as provided in 6.45(B) and (C); the rule states this loading limitation is equivalent to approximately one sixth of an acre of applicant's lot area per bedroom
rules.sos.ri.govR.I. Gen. Laws 46-23-6(2)(iii): the authority of the Coastal Resources Management Council over land areas above the mean high water mark shall be limited to two hundred feet from the coastal physiographic feature or to that necessary to carry out effective resources management programs, and the council's authority over these land uses and activities shall be limited to situations in which there is a reasonable probability of conflict with a plan or program for resources management or damage to the coastal environment
webserver.rilegislature.govR.I. Gen. Laws 31-1-3: (f) a camping recreational vehicle is a vehicular type camping unit, certified by the manufacturer as complying with ANSI A119.2 Standards, designed primarily as temporary living quarters for recreation, the basic units being tent trailers, fifth-wheel trailers, motorized campers, travel trailers and pick-up campers; (gg) a travel trailer is a towable recreational vehicle not exceeding three hundred twenty square feet in area, eligible to be registered for highway use; (x) a park trailer is a camping recreational vehicle eligible to be registered for highway use, built on a single chassis mounted on wheels and certified by the manufacturer as complying with ANSI A119.5
webserver.rilegislature.gov
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