Accessory Structures in Massachusetts (2026)
60 rules on the books across Massachusetts, 22 cities and counties. Select a rule to read the full details.
Severity: Few Restrictions · Light Restrictions · Some Restrictions · Significant Restrictions · Heavy Restrictions
ADU Rules
Rules for building accessory dwelling units (granny flats, in-law suites) including size limits, parking requirements, and owner-occupancy rules.
Massachusetts: statewide
StatewideFew RestrictionsThe 2024 Affordable Homes Act amended MGL Chapter 40A to require all Massachusetts municipalities to allow accessory…
Read full rule →New Bedford
Significant RestrictionsNew Bedford lets owners of single-family homes add one accessory dwelling unit by special permit from the Board of…
Read full rule →Attleboro
Some RestrictionsUnder Massachusetts law (Ch. 358 of Acts of 2024, effective Feb 2025), ADUs under 900 sq ft are allowed by right on…
Read full rule →Boston
Some RestrictionsADUs are now allowed by right statewide in Massachusetts under the 2024 Affordable Homes Act, with a maximum of 900…
Read full rule →Brockton
Some RestrictionsBrockton allows accessory dwelling units under Zoning Ordinance § 27-35.2, adopted January 30, 2025 to implement the…
Read full rule →Chelsea
Some RestrictionsADUs are now allowed by right in Chelsea under Massachusetts Affordable Homes Act (Ch. 150, Acts of 2024, §8, effective…
Read full rule →Fall River
Some RestrictionsUnder Massachusetts law (Ch. 358 of Acts of 2024, effective Feb 2025), ADUs under 900 sq ft are allowed by right on…
Read full rule →Leominster
Some RestrictionsLeominster allows one accessory dwelling unit by right in any Residential district under Article XV of the zoning…
Read full rule →Lynn
Some RestrictionsLynn allows one accessory dwelling unit by right on single-family lots, adopted February 11, 2025 under the state…
Read full rule →Plymouth County
Some RestrictionsSince February 2025 an accessory dwelling unit up to 900 square feet is allowed by right in every single-family zone…
Read full rule →Revere
Some RestrictionsRevere allows accessory dwelling units in its RA, RA1, RB and RB1 districts, capped at 900 square feet or half the…
Read full rule →Springfield
Some RestrictionsSpringfield allows one accessory dwelling unit per lot in Residence A and A-1 districts by Tier 1 site plan review…
Read full rule →Taunton
Some RestrictionsTaunton allows accessory dwelling units under Zoning Ordinance § 440-710, capped at 900 square feet or 50% of the…
Read full rule →Worcester
Some RestrictionsWorcester allows ADUs on properties with existing single-, two-, or three-family dwellings as of January 2024. ADUs are…
Read full rule →Cambridge
Few RestrictionsCambridge allows accessory dwelling units by right under the 2024 MA Affordable Homes Act and MGL c.40A s.3A, the…
Read full rule →Lowell
Few RestrictionsLowell allows one accessory dwelling unit by-right on any lot that permits single-family homes, capped at 900 square…
Read full rule →Newton
Few RestrictionsNewton allows ADUs by right on most residential lots under MGL c.40A s.3A (Affordable Homes Act 2024); Newton has…
Read full rule →Quincy
Few RestrictionsQuincy allows ADUs by right under MGL c. 40A §3 and the 2024 Affordable Homes Act. One ADU per single-family lot is…
Read full rule →Somerville
Few RestrictionsSomerville was an early Massachusetts adopter of ADU zoning and now complies with the 2024 Affordable Homes Act…
Read full rule →Weymouth
Few RestrictionsWeymouth Town Council passed ADU Ordinance Amendment (Measure 24-119) adding Article 29 to Chapter 120. ADUs are…
Read full rule →ADU Owner Occupancy
Whether the property owner must live on-site to operate an ADU, deed-restriction requirements, and recent state-law changes lifting owner-occupancy rules.
Boston
Some RestrictionsThe Zoning Code allows one detached and one non-detached accessory dwelling unit per lot, but conditions both on…
Read full rule →Newton
Some RestrictionsTo build a detached accessory dwelling unit larger than 1,000 square feet, up to the 1,200-square-foot by-right…
Read full rule →Springfield
Some RestrictionsSpringfield does not require the owner to live on site, but it does require the principal house and any accessory…
Read full rule →ADU Rental Restrictions
Whether an ADU can be rented short-term (Airbnb), 30-day minimums, separate rental licenses, and long-term lease requirements.
Taunton
Heavy RestrictionsTaunton bars accessory dwelling units from operating as short-term rentals. Zoning Ordinance § 440-710A states plainly…
Read full rule →Newton
Significant RestrictionsNewton's accessory dwelling unit ordinance bars short-term rentals: under Sec. 6.7.1(C)(4), whenever the ADU or the…
Read full rule →Revere
Significant RestrictionsRevere's zoning ordinance flatly bars renting out an accessory dwelling unit as a short-term rental, cross-referencing…
Read full rule →Springfield
Significant RestrictionsSpringfield's zoning ordinance bars any accessory dwelling unit from being used as a short-term rental…
Read full rule →Shed & Carport Rules
When a storage shed or carport needs a permit, the square-footage exemption thresholds, and the setback and height limits that apply either way.
Boston
Some RestrictionsA shed or other accessory building in Boston's rear yard is capped at 15 feet in height and must sit at least 4 feet…
Read full rule →Brockton
Some RestrictionsA shed or other detached accessory structure in Brockton must sit at least 5 feet off the side and rear lot lines, at…
Read full rule →Cambridge
Some RestrictionsIn Cambridge's Residence C-1 zoning district, an accessory building such as a shed or garage cannot sit closer to any…
Read full rule →Chelsea
Some RestrictionsChelsea's zoning ordinance keeps accessory structures, including a tool shed, greenhouse or garage, out of the required…
Read full rule →Fall River
Some RestrictionsDetached garages and sheds in Fall River must sit at least 20 feet from the street, 6 feet from any building, and 4…
Read full rule →Leominster
Some RestrictionsIn Leominster, Massachusetts, a detached shed or garage that is not used for human occupancy and is no more than one…
Read full rule →Lowell
Some RestrictionsIn Lowell, storage sheds over 200 square feet require a building permit; sheds up to 200 square feet and 16 feet tall…
Read full rule →Lynn
Some RestrictionsLynn's 2025 Zoning Ordinance caps accessory structures like sheds and garages at 15 feet in height for one- and…
Read full rule →New Bedford
Some RestrictionsNew Bedford caps a storage shed at 200 square feet, 12 feet tall, with no plumbing or heating and a foundation no…
Read full rule →Newton
Some RestrictionsNewton caps backyard sheds and other accessory buildings at 700 square feet of ground floor area, a maximum height of…
Read full rule →Quincy
Some RestrictionsQuincy, Massachusetts (Norfolk County) zoning allows toolsheds and storage sheds up to 10 feet tall in every residence…
Read full rule →Revere
Some RestrictionsA backyard shed, detached garage or other accessory structure in Revere cannot exceed one story or fifteen feet in most…
Read full rule →Somerville
Some RestrictionsSomerville caps backyard sheds at 12 feet in height and lets them sit as close as 3 feet from a side or rear lot line…
Read full rule →Springfield
Some RestrictionsSpringfield caps detached accessory structures like sheds at 15 feet in most residential districts and requires a…
Read full rule →Worcester
Some RestrictionsCarports in Worcester are regulated as accessory structures under the Worcester Zoning Ordinance (Article IV) and the…
Read full rule →Taunton
Light RestrictionsTaunton lets small accessory structures like sheds skip a building permit, but caps their shape and cuts required…
Read full rule →Plymouth County
Few RestrictionsA small shed skips the building permit everywhere in Plymouth County. The state code exempts a one-story detached…
Read full rule →Garage Conversions
Rules for converting a garage into living space, including whether you need to replace the lost parking and what building codes apply.
Attleboro
Some RestrictionsGarage conversions in Attleboro require building permits and must comply with the zoning ordinance and 780 CMR building…
Read full rule →Boston
Some RestrictionsGarage conversions to ADUs are explicitly allowed under the 2024 MA Affordable Homes Act by right on single-family…
Read full rule →Bristol County
Some RestrictionsGarage conversions throughout Bristol County require building permits and must comply with local zoning ordinances and…
Read full rule →Brockton
Some RestrictionsGarage conversions in Brockton require a building permit and must comply with the Massachusetts State Building Code for…
Read full rule →Brookline
Some RestrictionsBrookline's 2024 ADU bylaw amendment eliminates the prior 5-year age requirement for garage conversions to ADUs…
Read full rule →Chelsea
Some RestrictionsGarage conversions to living space in Chelsea require a building permit and zoning compliance. Under the MA Affordable…
Read full rule →Lowell
Some RestrictionsPer the Massachusetts State Building Code, a building permit is required to change the use or occupancy of a structure…
Read full rule →Newton
Some RestrictionsConverting a Newton garage to living space requires building permits, zoning review, and must meet habitable space…
Read full rule →Norfolk County
Some RestrictionsGarage conversion rules in Norfolk County are set by each municipality through zoning bylaws and building codes. A…
Read full rule →Revere
Some RestrictionsGarage conversions in Revere require a building permit and zoning compliance. Under the MA Affordable Homes Act (2025)…
Read full rule →Somerville
Some RestrictionsConverting a garage to living space in Somerville requires a building permit and may qualify as an ADU under the 2024…
Read full rule →Weymouth
Some RestrictionsGarage conversions to ADUs in Weymouth are permitted under the 2025 ADU ordinance (Article 29). Conversions require a…
Read full rule →Worcester
Some RestrictionsGarage conversions to living space in Worcester require building permits and full residential code compliance…
Read full rule →Tiny Homes
Zoning rules for tiny houses on wheels and foundations, including minimum square footage requirements and where they can be placed.
Lynn
Some RestrictionsLynn bans tiny homes on wheels as dwellings. ADUs may not occupy RVs, campers, or structures on wheels. A tiny home on…
Read full rule →Plymouth County
Some RestrictionsA tiny home's rules in Plymouth County turn on its foundation. Built on a permanent foundation at 900 square feet or…
Read full rule →Somerville
Some RestrictionsSomerville's zoning ordinance permits one detached Backyard Cottage per lot in the Neighborhood Residence district…
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