Salem, MA
Salem, MA Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 6/10 (10 is most accepting)
Last updated: 10.10.2024
Image source: Norwell Social
What You Need To Know
Salem, like all of Massachusetts since the passage of the 2024 Affordable Homes Act, allows ADUs by right. Each town has slightly different rules surrounding ADUs, but they all must adhere to the framework outlined by the state. In Salem, one ADU per single-family home is allowed. Separately, owners who choose to rent their ADUs at or below 70% of the Fair Market Rent limit in Salem are eligible for a property tax exemption on their ADU.
Type of ADU Permit Required
ADUs in Salem do not require special permits, and can be built using a traditional building permit. For lots with two-five units, owners may apply for a special permit to build up to one ADU per unit. ADUs are not permitted on lots with over five units in Salem.
ADU Rules
An ADU can be maximum 900 square feet or half the Gross Floor Area of the main house; whichever is smaller.
The ADU and the main house must be owned by the same person(s).
Short-term rentals are prohibited.
No additional parking is required for an ADU.
ADUs may be attached or detached from the main house - if detached, they must be built at least 10 feet from the main house.
ADUs cannot be built in the front yard.
Detached ADUs can have a maximum height of 18 feet
Attached ADUs must maintain the architectural style of the main house to the extent possible.
ADUs must have a separate entrance from the main house - attached ADUs can share an entry hall with the main house, but need a separate entry within the entry hall.
Exterior stairways need to be built on the side or rear of the ADU or main home.
Detached ADUs that are not owner occupied must have utilities on a separate service.
Resources:
https://library.municode.com/ma/salem/codes/zoning_ordinance?nodeId=S3.0USRE_3.2ACUS (See section 3.2.8)
Wayland, MA
Wayland, MA Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 4/10
Last updated: 11.14.2024
Image source: Town of Wayland Facebook
What You Need To Know
Wayland, like all of Massachusetts since the passage of the 2024 Affordable Homes Act, allows ADUs by right. Each town has slightly different rules surrounding ADUs, but they all must adhere to the framework outlined by the state. The rules for Wayland are outlined below.
Type of ADU Permit Required
ADUs in Wayland do not require special permits, and can be built using a traditional building permit.
ADU Rules
ADU Rules in Wayland:
Wayland allows one ADU per lot by right. To build more than one ADU, a special permit must be approved through the town.
An ADU can be maximum 900 square feet, or half the Gross Floor Area of the main house; whichever is smaller.
ADUs may be attached or detached from the main house.
Short-term rentals are not allowed. The minimum rental time for ADUs is 31 days.
ADUs must have a separate entrance from the main house - attached ADUs can share an entry hall with the main house, but need a separate entry within the entry hall.
If the ADU is within 0.5 miles of a transit station, no additional parking is needed. If it is further than 0.5 miles from a transit station, one off-street parking spot must be added.
In addition to the by right ADU, Wayland, via special permit, allows for an Affordable Accessory Dwelling Unit. For more information on this path, please see the link below.
Resources:
Norwell, MA
Norwell, MA Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 6/10 (10 is most accepting)
Last updated: 10.10.2024
Image source: Norwell Social
What You Need To Know
ADUs are allowed by right in Norwell both detached and within existing homes. As the rules are written currently, if you want to build a detached ADU, you need to go through site plan review from the Planning Board.
Type of ADU Permit Required
ADUs require a building permit, but detached ADUs specifically require site plan review.
ADU Rules
Interior ADUs:
Entrance: Must have a separate entrance, either directly outside or via a shared corridor meeting building code requirements for egress.
Size: Maximum floor area is the lesser of 900 square feet or 50% of the principal dwelling's floor area.
Short-Term Rentals Prohibited: Restrictive covenant required, enforceable by the Town, prohibiting short-term rental use.
Bedroom Limit: Restricted to one bedroom.
Parking: Must have one dedicated parking space; principal dwelling must have at least two. Shared driveway usage required.
Appearance: Entrance and parking must maintain the single-family residential look; separate entrances should be less visible than the main entrance from the street.
Owner Occupancy: Either the principal dwelling or the ADU must be owner-occupied at all times.
Sewage Approval: Board of Health must approve sewage disposal according to Title 5 and other regulations.
Commercial Use: No commercial use allowed except for permitted home occupations.
Detached ADUs:
Entrance: Must have a separate entrance meeting state building code requirements.
Size: Maximum floor area is the lesser of 900 square feet or 50% of the principal dwelling's floor area. If part of a larger accessory structure, the ADU's designated space must meet this limit.
Short-Term Rentals Prohibited: Same restrictive covenant rules as interior ADUs.
Bedroom Limit: Restricted to one bedroom.
Parking: Requires one dedicated parking space; principal dwelling must have at least two. Shared driveway usage required.
Owner Occupancy: Either the principal dwelling or the detached ADU must be owner-occupied at all times.
Sewage Approval: Same sewage disposal approval as interior ADUs.
Design Standards: Must maintain the single-family residential appearance and adhere to setbacks. Detached ADUs cannot be located in front of the principal dwelling. Architectural design must align with the principal dwelling and requires site plan review.
Rental Use: Only one unit (either the principal dwelling or the ADU) can be rented at a time. Owners may reside in the ADU while renting out the principal dwelling.
Commercial Use: No commercial use allowed except for permitted home occupations.
Resources:
Burlington, MA
Burlington, MA Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 5/10
Last updated: 11/3/2025
Image source: HDPT Physical Therapy
What You Need To Know
Burlington, like all of Massachusetts since the passage of the 2024 Affordable Homes Act, allows ADUs by right. Each town has slightly different rules surrounding ADUs, but they all must adhere to the framework outlined by the state. The rules for Burlington are outlined below.
Type of ADU Permit Required
ADUs in Burlington do not require special permits, and can be built using a traditional building permit. Residents are allowed to build one ADU per lot.
ADU Rules
An ADU can be maximum 900 square feet, or half the Gross Floor Area of the main house; whichever is smaller.
Short-term rentals are not allowed.
Detached ADUs cannot be built closer to the road than the main house.
Both the main house and the ADU must be connected to public water and sewer systems.
Properties within ½ mile of a transit station do not require additional parking. Properties outside of that area require additional off-street parking (driveway or garage) for all cars owned by the occupants of the ADU.
If an ADU has a separate exterior entrance or is detached, the ADU must be accessible from a path or walkway.
Attached ADUs must maintain the architectural style of the main house to the extent possible.
ADUs must have a separate entrance from the main house - attached ADUs can share an entry hall with the main house, but need a separate entry within the entry hall.
Exterior entrances for attached ADUs must be located on the side or back of the dwelling, so that the main house retains the appearance of having only one front door.
The main house and ADU must be owned by the same person(s).
Exterior staircases above the first floor are only allowed in special circumstances.
Resources:
Resources:
https://www.burlington.org/ArchiveCenter/ViewFile/Item/608 (See pages 135-137)
Hingham, MA
Hingham, MA Accessory Dwelling Unit (ADU) Rules
Last updated: 12/1/2025
Image source: See Plymouth
What You Need To Know
Hingham, like all of Massachusetts since the passage of the 2024 Affordable Homes Act, allows ADUs by right. Each town has slightly different rules surrounding ADUs, but they all must adhere to the framework outlined by the state. The rules for Hingham are outlined below.
Type of ADU Permit Required
ADUs in Hingham do not require special permits, and can be built using a traditional building permit. Residents are allowed to build one ADU per lot.
ADU Rules
An ADU can be maximum 900 square feet, or half the Gross Floor Area of the main house; whichever is smaller.
ADUs may be attached or detached from the main house.
Short-term rentals are not allowed - the minimum rental term for an ADU in Hingham is 30 days.
Properties within ½ mile of a transit station do not require additional parking. Properties outside of that area require one additional off-street parking spot.
Attached ADUs must maintain the architectural style of the main house to the extent possible.
ADUs must have a separate entrance from the main house - attached ADUs can share an entry hall with the main house, but need a separate entry within the entry hall.
Exterior entrances must be on the side or back of the main house.
Exterior staircases above the first floor are only allowed on the back of an ADU, and only under special circumstances.
The main house and ADU must be owned by the same person(s).
Resources:
https://www.hingham-ma.gov/DocumentCenter/View/25969/2025-Hingham-Zoning-By-Law_Clean?bidId= (See pages 136-138 of PDF)
Kingston, MA
Kingston, MA Accessory Dwelling Unit (ADU) Rules
Last updated: 12/05/2025
Image source: See Plymouth
What You Need To Know
Kingston, like all of Massachusetts since the passage of the 2024 Affordable Homes Act, allows ADUs by right. Each town has slightly different rules surrounding ADUs, but they all must adhere to the framework outlined by the state. The rules for Kingston are outlined below.
Type of ADU Permit Required
ADUs in Kingston do not require special permits, and can be built using a traditional building permit. Residents are allowed to build one ADU per lot.
The rules below are for building a by right ADU - there is also another type of ADU that can be built using a special permit. The rules and pathway for those ADUs are in most cases more complex. They can be found in the link in the resources section at the bottom of this page.
ADU Rules in Kingston:
An ADU can be maximum 900 square feet, or half the Gross Floor Area of the main house; whichever is smaller.
ADUs may be attached or detached from the main house.
Short-term rentals are not allowed.
Properties within ½ mile of a transit station do not require additional parking. Properties outside of that area require one additional off-street parking spot for the ADU.
ADUs must have a separate entrance from the main house - attached ADUs can share an entry hall with the main house, but need a separate entry within the entry hall.
Resources:
https://www.kingstonma.gov/DocumentCenter/View/5817/2025-Annual-Town-Meeting-Warrant?bidId=
(See pages 27-31)
Wellesley, MA
Wellesley, MA Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 6/10
Last updated: 10.29.2024
Image source: Town of Wellesley Facebook
What You Need To Know
Currently not in compliance with the Massachusetts Affordable Homes Act.
ADU rules in Wellesley are pretty relaxed but still do not conform to the new Affordable Homes Act because of the permits needed and approval from the Planning Department.
Type of ADU Permit Required
ADUs require a building permit from the Inspector of Buildings and an annual certificate from the Planning Department.
ADU Rules
ADUs must match the principal dwelling’s style, including siding, roof pitch, trim, windows, and doors.
Exterior ADU doors cannot face public streets or private ways unless in pre-existing detached structures.
Exterior staircases must be hidden from public view and complement the main dwelling.
ADU construction must not exceed the principal dwelling’s height before ADU construction.
Detached ADUs are allowed only in the rear or side yard or in pre-existing buildings.
ADU size: minimum of 250 sq ft, maximum of 900 sq ft or 50% of the main dwelling’s gross area.
ADU must meet all applicable area and yard regulations.
Operational Requirements:
ADU owners must file a notice with the Registry of Deeds.
Owners must reside on the property for at least 184 days per year and cannot lease the owner unit when absent.
Minimum lease term for the non-owner-occupied unit is 30 days.
No product pickups or deliveries beyond typical residential activities.
ADUs cannot be used for a home business.
Resources:
https://wellesleyma.gov/DocumentCenter/View/30044/Section-513-Accessory-Dwelling-Units
Rehoboth, MA
Rehoboth, MA Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 2/10 (10 is most accepting)
Last updated: 10.29.2024
Image source: Massachusetts Municipal Association
What You Need To Know
Currently not in compliance with the Massachusetts Affordable Homes Act.
In-law apartments are the only defined unit type in Rehoboth and can not must be used as an extension of the main dwelling.
Type of ADU Permit Required
Currently, a special permit is required, but that will have to change once Rehoboth rewrites their rules to be compliant with the state guidelines.
ADU Rules
Definition: An in-law apartment is an extension of a single-family dwelling providing facilities for sleeping, eating, bathing, and living.
Egress Requirements: The in-law unit must have a code-compliant means of egress through the main dwelling; garages or service areas cannot serve as the primary egress.
Size Limit: The total livable area of the in-law apartment cannot exceed 750 square feet.
Rental Restriction: The in-law apartment cannot be rented as a separate or independent unit from the main dwelling.
Unit Limitation: Only one in-law apartment is allowed per single-family dwelling.
Notarized Letter Requirement: Before a building permit is issued, the owner must submit a notarized letter stating:
The owner will occupy one of the dwelling units as their primary residence, except for temporary absences.
The in-law apartment is an extension of the single-family dwelling and is not an independent rental unit.
Recording Requirement: The notarized letter must be recorded in the County Registry of Deeds or Land Court within the property's chain of title.
Resources:
Hanover, MA
Hanover, MA Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 2/10 (10 is most accepting)
Last updated: 10.29.2024
Image source: Wikipedia
What You Need To Know
Currently not in compliance with the Massachusetts Affordable Homes Act.
ADUs currently are only allowed to be built for families to live closer to one another. Also, ADUs can only be created within an existing single family home.
Type of ADU Permit Required
A special permit is needed and the owner(s) must file a Declaration of Covenants at the Plymouth County Registry of Deeds stating that the use of the ADU shall be restricted to relatives of the owner.
ADU Rules
Definition and Permitting: ADUs must be self-contained housing within a single-family dwelling (not in accessory structures) and require a special permit from the Zoning Board of Appeals.
Occupant Requirement: ADUs are designated for individuals related to the primary owner-occupant by blood, marriage, or adoption.
Limitations on Units: Only one ADU is allowed per dwelling and per residential lot.
Owner Occupancy: The owner must occupy one of the units as their primary residence, with exceptions for temporary absences.
Exterior Access: New exterior stairs for the ADU must be located on the side or rear, unless otherwise required by building codes.
Parking: Off-street parking must be provided for both owner-occupants and tenants; specific requirements are determined by the Zoning Board of Appeals.
Size Limits: ADU size is capped at 33% of the gross area of the primary residence (or 800 square feet, whichever is smaller).
Bedroom Limit: ADUs may have a maximum of two bedrooms.
Code Compliance: ADUs must meet State Building Code, State Sanitary Code, and local bylaws.
Familial Affidavit: ADU applications must include an affidavit confirming the familial relationship between occupants and owners.
Annual Certification: Owners must re-certify occupancy and family status with the Building Commissioner yearly and notify of tenant changes within 30 days.
Recorded Declaration: Owners must file a Declaration of Covenants with the Plymouth County Registry, restricting ADU use to relatives of the property owner.
Existing ADUs: ADUs existing before the bylaw must comply with the State Building Code; each case is reviewed individually.
Administration: The Building Commissioner oversees administration, issues permits, and enforces compliance. No ADU may be occupied without a certificate of occupancy.
Continuous Use: Permits for construction or special use must adhere to subsequent bylaw amendments unless construction begins within six months.
Documentation Requirement: ADUs without proper documentation may incur fines as per Section 12.500 of the Hanover Zoning Bylaw.
Sale Restriction: ADUs cannot be sold separately from the principal dwelling.
Resources:
Stoneham, MA
Stoneham, MA Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 4/10
Last updated: 10.29.2024
Image source: Town of Stoneham
What You Need To Know
Currently not in compliance with the Massachusetts Affordable Homes Act.
A single ADU is allowed with a permit on single-family home properties, must share a wall with the main structure and can not exceed 750 SF. Permits are not transferrable to new owners outside of the family.
Type of ADU Permit Required
ADUs require a special permit.
ADU Rules
Permit Filing: A Special Permit is required, filed with the Registry of Deeds, and can be amended or rescinded if ownership or conditions change.
Automatic Reversion: If ownership changes outside of the family, the property reverts to single-family use unless a new permit is applied for.
Size and Structure: The ADU cannot exceed 750 square feet and must share at least 75% of a wall with the main dwelling; utilities must be single-metered.
Parking: One additional parking space is required for the ADU, in addition to two spaces for the primary residence.
Occupancy Limit: ADU occupancy is limited to two people and cannot be used for commercial purposes.
Deed Restriction: A deed restriction confirming owner occupancy must be filed, and a Certificate of Occupancy requires proof of the permit’s recording.
Single Ownership: The main and accessory dwellings must be under the same ownership and cannot be separated. Only one ADU is permitted per lot.
Resources:
https://www.stoneham-ma.gov/DocumentCenter/View/1223/Ch15-Zoning-Part-1
Reading, MA
Reading, MA Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 5/10
Last updated: 10.29.2024
Image source: Reading Recap
What You Need To Know
Currently not in compliance with the Massachusetts Affordable Homes Act.
A single ADU is allowed with a permit on single-family home properties. The ADU size cannot exceed one third of the residence and must maintain a single family appearance. Occupants limited to three.
Type of ADU Permit Required
ADUs require a special permit.
ADU Rules
An Accessory Apartment must not exceed the lesser of 1,000 square feet or one-third of the gross floor area of the primary residence, excluding garages, unfinished basements, sheds, or other accessory structures.
At least one owner must reside in either the Principal Dwelling or Accessory Apartment on the property.
The Accessory Apartment should maintain the single-family appearance of the property; new entries must be on the side or rear, and stairways to upper-level apartments should be enclosed within the building.
All motor vehicles associated with the Accessory Apartment must be parked off the street in a driveway or garage, without compromising the neighborhood’s single-family character.
Both the Principal Dwelling and Accessory Apartment must be connected to public water and sewer systems.
The apartment is limited to two bedrooms and a maximum of three occupants.
For detached structures built before 1910 or listed in the Historical Inventory, any exterior alterations should preserve the structure’s historical features, with limited footprint expansion (up to 10%).
A Detached Accessory Apartment cannot be located in the front yard or any area between the Principal Dwelling and a right-of-way, unless an existing structure in that area is converted.
Any Special Permit issued must ensure that the Accessory Apartment maintains the neighborhood's character and complements the Principal Dwelling.
Resources:
https://www.readingma.gov/DocumentCenter/View/2242/Zoning-Bylaw-PDF - page 38
Fairhaven, MA
Fairhaven, MA Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 4/10 (10 is most accepting)
Last updated: 9.19.2024
Image source: Fairhaven Visitors Center Facebook
What You Need To Know
Currently not in compliance with the Massachusetts Affordable Homes Act.
ADUs are only allowed by converting an existing space within a single-family dwelling.
Type of ADU Permit Required
ADUs require a special permit in Fairhaven.
ADU Rules
Dwelling conversions shall not be allowed unless the lot meets the minimum lot size in § 198-18 or 22,500 square feet, whichever is greater.
Units created through dwelling conversions shall not be less than 1,000 square feet, not including areas of the basement, attic or garage.
The applicant shall illustrate to the Planning Board that the requirements of the State Building Code are met.
Site requirements.
No expansion to the existing structure.
Parking shall be as provided for in § 198-27B(1).
No portion of the basement, attic or garage may be used for dwelling purposes.
Use of an existing on-site septic system to service proposed units shall be permitted only upon approval of the Board of Health.
Resources:
Gloucester, MA
Gloucester, MA Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 7/10 (10 is most accepting)
Last updated: 9.19.2024
Image source: City of Gloucester
What You Need To Know
ADUs are permitted within an existing single family home, attached, and detached in Gloucester.
Type of ADU Permit Required
ADUs that conform to the rules listed below require a building permit through the building inspector. Special permits may be granted through the zoning board of appeals if the requirements cannot be met.
ADU Rules
The owner(s) of the single-family dwelling in which the accessory dwelling unit is created must continue to occupy one of the units as their residence, except for bona fide temporary absences.
Where the ADU or the principal dwelling is occupied as a rental unit, the minimum occupancy or rental term shall be 30 days. No ADU shall be use for boarding or lodging purposes or used as a rental unit on a weekly or daily basis.
There shall be one off-street parking space for the ADU in addition to off- street parking spaces required for the principal dwelling. The parking space shall be constructed of materials consistent with the existing driveway and shall have vehicular access to the driveway. No parking shall be located between the front building line of the principal dwelling and the front lot line except in the existing driveway.
Where the driveway is located within 10 feet of the side lot line, at least four feet of the driveway side yard, measured from the side lot line, shall be a landscaped buffer zone within which parking shall be prohibited. The landscape buffer zone shall be sufficient to screen the parking from the abutting property
There shall not be more than one ADU on a lot. ADUs shall not be eligible for zoning dimensional variances proposing to increase the allowable number of ADUs on a lot. No ADU shall be separated from the principal dwelling through a condominium or cooperative conversion process or be held in separate ownership from the principal dwelling unit on the lot.
The construction of any ADU shall conform with the State Building Code and Title V of the State Sanitary Code, and shall be lawful under all other provisions of applicable health, building, zoning and other local laws and regulations.
The Planning Board shall have authority to adopt an ADU guidance document providing interpretation and guidelines to administer this Section 5.24.
For Attached ADUs
The ADU shall be located entirely inside the single-family structure, except as provided for in 5.24.4(c).
The accessory dwelling unit shall be designed to maintain the appearance of a single-family dwelling, subject to the following requirements.
The accessory dwelling unit shall be designed to maintain the appearance of a single-family dwelling, subject to the following requirements.
All stairways to an ADU above the first floor shall be enclosed within the exterior walls of the single-family structure or on the rear of the structure if constructed on an outer wall.
Where two or more entrances exist on the front facade of the single-family dwelling, one entrance shall appear to be the principal entrance and other entrances shall appear to be secondary. In the alternative the ADU may be accessed by a side or rear entry.
Exterior alterations are permitted provided they are in keeping with the architectural integrity of the structure, including, but not limited to, the following considerations:
The exterior finish material should be the same or visually consistent in type, size, and placement, as the exterior finish material of the remainder of the building;
Trim should be consistent in type, size, and location as the trim used on the remainder of the building;
Windows should be consistent with those of the remainder of the building in proportion and orientation;
Exterior staircases should be designed to minimize visual intrusion and be complementary to the existing building.
For Detached ADUs
A Detached ADU shall be maximum of 900 square feet or 50 percent of the total habitable space of the principal dwelling, whichever is less.
Alterations to an existing accessory structure or the creation of a new accessory structure for a Detached ADU are permitted provided they are in keeping with the architectural integrity of the existing principal dwelling on the lot and the residential character of the neighborhood. The exterior finish material should be the same or visually compatible in type, size, and placement, as the exterior finish material of the principal dwelling unit on the site.
For new construction of a Detached ADU, the building shall comply with the district's minimum setback requirements for accessory structures. The maximum height of the building shall be:
20 feet if the structure meets the normal accessory building setbacks, or
24 feet if the structure meets the normal principal dwelling setbacks.
Resources:
https://library.municode.com/ma/gloucester/codes/zoning_ordinance?nodeId=SVSPRE_5.24ACDWUNAD
Dunstable, MA
Dunstable, MA Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 2/10 (10 is most accepting)
Last updated: 9.13.2024
What You Need To Know
Currently not in compliance with the Massachusetts Affordable Homes Act.
Dunstable requires homeowners to jump through a number of hoops in order to build an ADU. If you have questions about the rules, please contact us. We would be happy to help!
Type of ADU Permit Required
A special permit is required through the zoning board of appeals.
ADU Rules
Except as otherwise provided in these Zoning Bylaws, not more than one accessory dwelling unit may be established on a lot [Amended 5/15/21]. The accessory dwelling unit shall not exceed 35% of the gross living space of the existing or expanded principal structure or 1,200 square feet, whichever is greater, and have no more than two bedrooms. The expansion of an existing structure to accommodate an accessory apartment shall not increase the gross floor space of the existing structure more than 15%.
The accessory dwelling unit may be located in the principal structure or in a detached accessory structure; provided, however, that an accessory dwelling unit may be located in such detached accessory structure only where such detached accessory structure has been in existence for at least ten (10) years. The burden shall be upon the applicant to demonstrate compliance with this subsection.
An accessory apartment shall be a complete dwelling unit with a separate entry, kitchen facilities, at least one bedroom, and a bathroom with sink, toilet and bathing facilities.
The external appearance of the structure in which the accessory dwelling unit is to be located shall not be significantly altered from the appearance of a single family structure or other structure ordinarily used and included in the context of single family dwellings, in accordance with the following:
The expansion of an existing structure to accommodate an accessory apartment shall not increase the gross floor space of the existing structure more than 15%.;
Any stairways or access and egress alterations serving the accessory dwelling unit shall be enclosed, screened, or located so that visibility from public ways is minimized;
Sufficient and appropriate space for at least one (1) additional parking space shall be provided by the owner to serve the accessory dwelling unit. Said parking space shall be constructed of materials consistent with the existing driveway and shall have vehicular access to the driveway;
All construction and/or renovation shall be performed in accordance with the applicable requirements of the State Building Code.
Prior to the conclusion of a Site Plan Review the owner must provide certification, by affidavit, that one of the two dwelling units shall be occupied by the owner of the property as his/her primary residence at least six months in any calendar year. In addition, such owner shall occupy such dwelling unit as his or her primary residence as a condition of the validity of the Special Permit. The owner must also own the entire lot, any structures thereon, and both dwellings.
The initial term and subsequent extensions of a special permit for an accessory dwelling unit shall terminate upon transfer of the ownership of the premises or when the owner no longer occupies the premises as his or her residence in accordance with Section (c) i above. Upon sale or transfer of the property to a new owner, the new owner must submit an affidavit to the Building Inspector of their intention to use one of the dwellings as their primary residence. A subsequent special permit may be granted after certification by affidavit is made by the applicant to the Board of Appeals that the accessory dwelling unit has not been extended, enlarged, or altered to increase its original dimensions, as defined in the initial special permit application.
Use and occupancy of any accessory apartment other than is authorized herein shall be grounds for revocation of any permit granted under this section.
Special Permits for an accessory dwelling unit may be issued by the Board of Appeals upon a finding that the construction and occupancy of the additional dwelling unit complies with foregoing provisions and will not be detrimental to the neighborhood in which the lot is located.
Nothing in this subsection 6.2.1 shall be construed to change or reduce any dimensional or area requirements of this Zoning Bylaw relative to single family dwellings and accessory structures thereto or to allow any uses not otherwise permitted by this Zoning Bylaw, other than accessory apartments as allowed.”
Resources:
Sudbury, MA
Sudbury, MA Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 9/10 (10 is most accepting)
Last updated: 9.11.2024
Source: Sudbury Chamber of Commerce
What You Need To Know
Sudbury, like all of Massachusetts since the passage of the 2024 Affordable Homes Act, allows ADUs by right. Each town has slightly different rules surrounding ADUs, but they all must adhere to the framework outlined by the state. The rules for Sudbury are outlined below.
Type of ADU Permit Required
ADUs in Sudbury can be built using a traditional building permit. They do not require a special permit.
ADU Rules
Sudbury allows one ADU per lot
An ADU can be maximum 900 square feet, or half the Gross Floor Area of the main house; whichever is smaller.
ADUs may be attached or detached from the main house.
ADUs cannot be used as short-term rentals.
ADUs must maintain a similar architectural style to the main house to the extent possible.
ADUs must have a separate entrance from the main house - attached ADUs can share an entry hall with the main house, but need a separate entry within the entry hall.
If the ADU is within 0.5 miles of a transit station, no additional parking is needed. If it is further than 0.5 miles from a transit station, one off-street parking spot must be added.
The main house and ADU must be owned by the same person(s).
Exterior stairways need to be built on the side or rear of the ADU or main home.
Resources:
Waltham, MA
Waltham, MA Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 2/10 (10 is most accepting)
Last updated: 9.10.2024
Source: City of Waltham MA
What You Need To Know
Currently not in compliance with the Massachusetts Affordable Homes Act.
Currently, ADUs are only allowed within an existing single family home. There is currently just an ADU definition on the books in Waltham, but there is nothing that specifies a size maximum or minimum, rental rules, or owner occupancy.
Type of ADU Permit Required
ADUs require a special permit through the Board of Appeals.
ADU Rules
Accessory dwelling units. The Board of Appeals shall only grant such special permit when it has determined that the following limitations have been complied with and the Board shall include the following in its decision:
The proposed dwelling unit is in harmony with and will promote the purposes of this chapter.
The dwelling unit is accessory to the principal residence and either the dwelling unit or the principal residence is occupied by the owner of the lot on which the dwelling unit is to be located, which owner shall have owned the lot for not less than five years.
The dwelling unit is designed for and may be occupied by not more than two persons.
Adequate provision has been made for access to such dwelling unit, separate from the access of the principal residence.
No alteration to the exterior of the dwelling shall be made.
No increase in the floor area of the dwelling shall be made.
The construction, reconstruction and occupancy of the dwelling unit will not be detrimental or injurious to persons or property.
The lot on which the dwelling is located contains at least 20,000 square feet in Residence A-1 Districts and 15,000 square feet in Residence A-2 Districts.
The building in which the proposed dwelling unit is to be located existed on the date of the adoption of this subsection.
There shall be provided on the lot a parking area sufficient to hold at least four cars designed in accordance with Sections 5.3 through 5.35 and in such a manner that cars can exit onto the street in a forward direction.
Any special permit granted under this section shall require that the applicant request recertification of the permit at periods not exceeding three years, and failure to request such recertification shall cause the permit to lapse. The Board of Appeals may, in appropriate cases, impose further restrictions on the apartment or the lot as a condition of the special permit.
The special permit, if granted, shall clearly state that it is not transferable to a purchaser of the lot and shall require, as a condition of its validity, that a copy of the permit be filed in the Registry of Deeds by the applicant.
Resources:
Winchester, MA
Winchester, MA Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 2/10 (10 is most accepting)
Last updated: 11/17/2025
Source: Town of Winchester Facebook
What You Need To Know
Winchester, like all of Massachusetts since the passage of the 2024 Affordable Homes Act, allows ADUs by right. Each town has slightly different rules surrounding ADUs, but they all must adhere to the framework outlined by the state. The rules for Winchester are outlined below.
Type of ADU Permit Required
ADUs in Winchester do not require special permits, and can be built using a traditional building permit. Residents are allowed to build one ADU per single-family home or duplex.
ADU Rules
An ADU can be maximum 900 square feet or half the Gross Floor Area of the main house; whichever is smaller.
In the case of duplexes, the ADU can be 900 square feet or half the Gross Floor Area of the larger unit; whichever is smaller.
ADUs may be attached, detached, or built within the main house.
Short-term rentals are not allowed - the minimum rental term for ADUs in Winchester is 31 days.
The main house and ADU must be owned by the same person(s).
Properties within ½ mile of a transit station do not require additional parking. Properties outside of that area require additional off-street parking (driveway or garage). e
Construction of a new garage for an ADU requires a special permit with the town.
ADUs should maintain the architectural style of the main house to the extent possible.
ADUs must have a separate entrance from the main house - attached ADUs can share an entry hall with the main house, but need a separate entry within the entry hall.
Exterior entrances for ADUs should be clearly secondary to the entry of the main house.
Exterior staircases above the first floor are only allowed within the home or on the side or back of the primary dwelling.
Resources:https://ecode360.com/42152935#42152939 (See Section 3.2.2)
Chelmsford, MA
Chelmsford, MA Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 2/10 (10 is most accepting)
Last updated: 9.10.2024
Source: Town of Chelmsford Facebook
What You Need To Know
Currently not in compliance with the Massachusetts Affordable Homes Act.
Currently, Chelmsford allows a form of an ADU that is referred to as a Limited Accessory Apartment (LAA). These can only be constructed within or attached to a single family dwelling.
Type of ADU Permit Required
To construct an ADU within an existing dwelling, a building permit through the building inspector is required. A special permit is required to build an ADU attached to the existing home.
ADU Rules
An LAA as defined in Chelmsford is a self-contained unit within an owner-occupied single-family dwelling, providing space for bathing, cooking, and sleeping, and used exclusively by extended family members. It does not convert the dwelling into a two-family unit.
The LAA must have separate ingress/egress that maintains the single-family appearance. New entrances should be at the side or rear, with enclosed staircases and internal doorways between the LAA and the main unit.
The LAA size is limited to 750 square feet, excluding stairs and common areas.
Adequate off-street parking required, consistent with neighborhood character. Utilities must be connected to town sewer, and separate metering is not required unless mandated by the State Building Code.
Only one LAA per lot and can have no more than two occupants.
LAAs must be used only by extended family. Use restrictions must be recorded in the Registry of Deeds and include provisions for owner-occupancy and notice to potential buyers.
The Building Inspector issues permits by right. Special permits are handled by the Zoning Board of Appeals, which also records restrictions in the Registry of Deeds.
Applicants must submit architectural plans, site plans, names of residents, and an executed use restriction.
Special permits are based on zoning bylaws. The Zoning Board of Appeals may allow deviations for accessibility features.
New owners must file applications and inspections will ensure compliance. Violations may result in permit lapses, fines, and required special permits for continued use.
Resources:
Millbury, MA
Millbury, MA Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 4/10 (10 is most accepting)
Last updated: 8.28.2024
What You Need To Know
Currently not in compliance with the Massachusetts Affordable Homes Act.
ADUs are allowed within all Residential and Suburban Districts on lots that meet the zoning district dimensional requirements or on lots/in structures that are legally pre-existing nonconforming.
Type of ADU Permit Required
ADUs require a special permit.
ADU Rules
Only one ADU is allowed on a lot.
The appearance of a single-family home must be kept in.
Any new entrance to the ADU must be either on the side or rear of the home.
The gross floor area of an ADU cannot be greater than 800 square feet.
Two off-street parking spaces must be provided for the residents of the ADU.
For ADUs built on lots with pre-existing nonconforming single-family homes, the living area of the existing single-family home cannot be increased in total square footage or footprint altered.
The Zoning Board of Appeals may allow in some circumstances deviations from certain requirements to accommodate individuals living needs.
Resources:
Middleborough, MA
Middleborough, MA Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 4/10
Last updated: 8.28.2024
Image source: Wikipedia
What You Need To Know
Middleborough, like all of Massachusetts since the passage of the 2024 Affordable Homes Act, allows ADUs by right. Each town has slightly different rules surrounding ADUs, but they all must adhere to the framework outlined by the state. The rules for Middleborough are outlined below.
Type of ADU Permit Required
ADUs in Middleborough do not require special permits, and can be built using a traditional building permit.
ADU Rules in Middleborough:
Middleborough allows one ADU per building lot.
An ADU can be a maximum of 900 square feet.
ADUs can be attached or detached from the main house.
Short-term rentals are prohibited.
Detached ADUs cannot be taller than 2 stories, or 25 feet - whichever is shorter.
ADUs must maintain the architectural style of the main house to the extent possible.
ADUs must have a separate entrance from the main house - attached ADUs can share an entry hall with the main house, but need a separate entry within the entry hall.
No multi-level exterior stairs are allowed as the main method of access to the ADU.
Detached ADUs cannot be built in the front yard.
Detached ADUs need to be built at least 10 feet from any other structure on the lot.
If the ADU is within 0.5 miles of a transit station, no additional parking is needed.
If it is further than 0.5 miles from a transit station, one off-street parking spot must be added.
If off-street parking is necessary, it must be in the side or back yard of the main house and use the existing driveway.
The water connection for the ADU must come from the main house.
ADUs must have a separate electric meter, located outside.
ADUs need a separate water shut off.
ADUs and the main house must remain in single ownership - a deed restriction recorded at the Registry of Deeds is required.
Propane is not allowed on a lot that has an existing gas connection (from MG&E) - we build all-electric homes, so this isn’t a problem!
Resources: