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)
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
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
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:
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)
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:
Pembroke, MA
Pembroke, MA Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 2/10 (10 is most accepting)
Last updated: 8.15.2024
Source: Town of Pembroke
What You Need To Know
Currently not in compliance with the Massachusetts Affordable Homes Act.
Currently, there are some hoops to jump through with ADUs in Pembroke. In addition to requiring a special permit, owners must sign a 15 year use restriction and agree to a maximum rent to be charged. ADUs must be rented to a person having an annual income of no more than 80% of the area median income. The Pembroke Housing Authority will monitor compliance with the ADU rules.
Type of ADU Permit Required
ADUs are allowed by special permit through the Zoning Board of Appeals in Pembroke.
ADU Rules
ADUs may be allowed on lots with at least 20,000 square feet of contiguous upland except for ADUs already in existence prior to the current ordinance.
The owner of the property must occupy the primary dwelling and rent the ADU.
The ADU cannot be larger than 800 square feet.
ADUs are limited to one bedroom and two occupants.
Two parking spaces must be provided for the ADU
An ADU must be attached to the existing single family home.
Resources:
Northborough, MA
Northborough, MA Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 7/10 (10 is most accepting)
Last updated: 8.14.2024
Source: Town of Northborough
What You Need To Know
Northborough, 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 Northborough are outlined below.
Type of ADU Permit Required
ADUs are permitted by right in Northborough and require a building permit.
ADU Rules
ADU Rules in Northborough:
Northborough allows one ADU per building lot.
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 prohibited.
ADUs can be attached or detached from the main house.
Attached and detached ADUs must maintain the architectural style of the main house to the extent possible.
ADUs should be no taller than the main house.
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.
When possible, a detached ADU must be built to the rear or side of the main house and 10 feet from other buildings on the lot.
Multi-level exterior staircases are not allowed on attached or detached ADUs.
One dedicated off-street parking spot must be added for the ADU.
Detached ADUs must have a separate water meter and dedicated water service from the main to the ADU.
When possible, the sewer service for a detached ADU should connect from the main house.
Any direct connections from the ADU to the public sewer must be reviewed and approved from the Department of Public Works.
The main house and ADU must be owned by the same person(s).
Resources:
https://www.town.northborough.ma.us/sites/g/files/vyhlif12221/f/uploads/warrant_articles_approved_at_2025_annual_town_meeting.pdf (See pages 1-2)
Marshfield, MA
Marshfield, MA Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 4/10 (10 is most accepting)
Last updated: 8.14.2024
Image source: WATD News
What You Need To Know
Currently not in compliance with the Massachusetts Affordable Homes Act.
ADUs are allowed via special permit in the R-1, R-2, R-3, B-1, and B-2 districts through the Board of Appeals. If you’d like help determining what is possible on your property, please reach out to our team!
Type of ADU Permit Required
ADUs are permitted through the Board of Appeals via a special permit.
ADU Rules
ADUs are limited to 40% of the total living area of the single-family dwelling and limited to one bedroom.
Only one ADU is allowed per lot.
ADUs are only allowed within existing single family dwellings currently.
ADUs must be designed so that the appearance of a single family home is maintained.
There are lot size requirements for specific districts:
For properties in B-1 and R-3 the lot size minimum is 10,000 square feet.
For properties in B-2 and R-2 the lot size minimum is 20,000 square feet.
For properties in R-1 the lot size minimum is 40,000 square feet.
One additional parking space must be provided for the ADU.
The ADU and the existing single family home must remain in common ownership.
If the property is sold, a new special permit must be applied for.
Each year, the owner of the property must recertify that the home is their primary residence.
Resources:
Plymouth, MA
Plymouth, MA Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 9/10 (10 is most accepting)
Last updated: 8.14.2024
Source: Yankee Magazine
What You Need To Know
ADUs are allowed detached or attached to an existing home in all residential or mixed use zoning districts.
Type of ADU Permit Required
ADUs require first a zoning application that includes a site plan with setbacks and dimensions as well as a floor plan with a layout of the existing home and proposed ADU. After that a building permit is required.
ADU Rules
ADUs cannot be greater than 900 square feet of floor area.
This is in line with the Affordable Homes Act!
ADUs cannot be used as a short-term rental.
The ownership of the ADU cannot be split between the ADU and the single-family home.
Condos and Townhomes are not considered single-family homes in Plymouth; therefore, ADUs would not be permitted on lots with townhomes or condos.
The ADU must conform to the setbacks and general site requirements of the zoning district where it is built.
Only one ADU is permitted per lot.
Resources:
https://www.plymouth-ma.gov/DocumentCenter/View/6428/Update-Zoning-Bylaw-4-2024 page 5 of PDF
https://www.plymouth-ma.gov/1342/Accessory-Dwelling-Unit-ADU-Information
Beverly, MA
Beverly, MA Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 9/10 (10 is most accepting)
Last updated: 7.9.2024
Source: Town of Beverly, MA
What You Need To Know
ADUs are permitted in Beverly within dwellings, attached, and detached. The intention for ADUs in Beverly is to create spaces for older individuals who want to remain in their homes or on their property as well as provide rental units.
Type of ADU Permit Required
ADUs are by right in Beverly and require a building permit.
ADU Rules
ADUs must be occupied by at least one of the owners of the property.
There is only one ADU allowed on a property.
ADUs must meet minimum requirements for sanitary and building codes as well as municipal codes.
All units on the property must have utility services, including electricity, water, oil, and gas, active if present.
The design of the ADU must be complementary to the primary dwelling.
ADUs are limited to 1,000 square feet or 50% of the primary dwelling’s gross floor area, whichever is less.
Side and rear setbacks must be met for the specific zoning district.
Short term rentals are not allowed.
Any exterior lighting must be designed and installed so that it does not cast light on adjacent properties.
One off-street parking spot must be provided and reserved for the ADU. The spot must be distinct from other off-street parking spaces.
The ADU must remain in common ownership.
Attached ADU provisions
One entrance is permitted on the front of the home, and the new entrance should be on the rear or side of the home if feasible. Any front entrance to an ADU must appear secondary.
Any stairways must be within the exterior.
Detached ADU provisions
Detached ADU cannot be taller than the existing dwelling and cannot be greater than 35 feet.
ADUs must appear clearly secondary to the primary dwelling and must be located behind the front building edge of the primary dwelling.
The design of the ADU must be complementary to the primary dwelling.
Resources:
Swampscott, MA
Swampscott, MA Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 8/10 (10 is most accepting)
Last updated: 7.2.2024
Image Source: North of Boston
What You Need To Know
Last winter, at Swampscott’s annual town meeting, a law was passed to make ADUs by right. There are a number of restrictions and design requirements based upon what type of ADU you want to build.
Type of ADU Permit Required
ADUs are permitted by right in Swampscott.
ADU Rules
Size Restrictions
Generally, ADUs are permitted to be as large as 50% of the floor area of the existing dwelling or 900 feet, whichever is smaller
Attached ADUs
If changing the footprint of an existing structure the floor area addition is limited to 800 square feet.
An addition of greater than 800 square feet is subject to site plan review by the Swampscott planning board
Detached ADUs can be built in two ways
ADUs can be built in existing detached accessory structures.
If in a preexisting, nonconforming location, it can be demolished and rebuilt within the same footprint. These cases are subject to a finding from the Zoning Board of Appeals.
If building a new construction detached ADU, the ADU must meet the dimensional requirements for a detached structure.
5 feet from side and rear setbacks and no less than 10 feet from the primary structure.
Additional Rules
Only one ADU is permitted per lot.
If an ADU is constructed where the entrance is located on the front of the home, only one entrance may appear to be the primary entrance.
Any exterior stairways to the ADU must be located on the side or rear of the dwelling.
All utilities must be shared between the ADU and the primary dwelling.
The owner of the lot must either live in either the primary dwelling or the ADU, except for a bona fide temporary absence.
In addition to minimum parking requirements, one additional parking space is required for the ADU.
Resources:
Town of Swampscott Zoning By-law- Article 5.11.0.0/Page 119
Arlington, MA
Arlington, MA Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 8/10
Last updated: 6.2.2024
Image source: Visit Lexington
What You Need To Know
Arlington, 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 Arlington are outlined below.
Type of ADU Permit Required
ADUs in Arlington do not require special permits, and can be built using a traditional building permit. If you have a particularly tight lot, it may be possible to get a special permit to reduce your setbacks.
ADU Rules in Arlington
ADUs are allowed in residential and business districts.
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, detached, or built within the existing house.
Short-term rentals are not allowed.
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 additional off-street parking spaces are required.
Owners don’t need to live on the property to build an ADU.
The main house and ADU must be owned by the same person(s).
Resources:
https://www.arlingtonma.gov/home/showpublisheddocument/43413/638962138242730000 (Pages 101-103)
https://www.arlingtonma.gov/departments/inspectional-services/accessory-dwelling-units-adus
https://arlington.novusagenda.com/Agendapublic/CoverSheet.aspx?ItemID=20003&MeetingID=2254
Lancaster, MA
Lancaster, Massachusetts’ Accessory Dwelling Unit (ADU) Rules
Last updated: 2024
Lancaster, MA Accessory Dwelling Unit (ADU) Rules
As of 4/22/2024
City Acceptance Rating:
5/10(10 is most accepting)
What you need to know about ADUs in Lancaster, MA:
ADUs have been possible in Lancaster under a special permit since 2007. The town of Lancaster does not specify whether the ADU must be attached, detached, or retrofitted; however, they have specific requirements detailing the size, aesthetic, and desired purpose of the ADU.
ADU permit requirements in Lancaster, NA:
A special permit is required for construction of ADUs in Lancaster.
The ADU Rules in Lancaster, MA:
The primary residence must have been built five years prior to building an ADU.
Either the primary residence and ADU must be owner occupied. Temporary absences are allowed for no more than 12 months.
The habitable size of the ADU is limited to ⅓ of the habitable square footage of the existing dwelling and the proposed ADU or 1,200 square feet, whichever is less.
The ADU must have a separate entrance from the primary residence, there can be no more than one entrance door on a single side, and there cannot be any exterior staircases.
The ADU cannot be designed to house greater than three people
If not on town water and sewer, the owner must document that appropriate water and sewer modifications have been made to accommodate the needs of the ADU.
There must be at least three parking spaces available.
There must be a benefit to the community under the following conditions:
There is a benefit to a community housing need or special need of the planned occupant.
The compatibility of the design in relation to the existing structure and neighborhood.
The construction impact to natural resources, privacy of neighbors, overall character of the neighborhood, and safety.
Resources:
https://ecode360.com/11813694 (scroll to the bottom of the page. Section G)
Updates:
https://www.ci.lancaster.ma.us/sites/g/files/vyhlif4586/f/pages/la2689-220a_use_regulation_schedule.pdf - Indicates that special permit is still required
https://ecode360.com/LA2689/laws/LF1884287.pdf - indicates there may be a new (unclear) zone that would make ADUs by right or just retrofit. Unclear to me (sam) at this time.
Medway, MA
Medway, Massachusetts’ Accessory Dwelling Unit (ADU) Rules
Last updated: 2019
What you need to know:
Medway, 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 Arlington are outlined below.
Type of ADU permit required:
ADUs in Medway do not require special permits, and can be built using a traditional building permit. If you have a particularly tight lot, it may be possible to get a special permit to reduce your setbacks.
ADU Rules in Medway:
Medway allows ADUs by right in single-family zoning districts.
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, detached, or built within the existing house.
Short-term rentals of ADUs are not allowed.
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.
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.
The main house and ADU must be owned by the same person(s).
Resources:
https://storage.googleapis.com/juniper-media-library/117/2025/10/Zoning%20Bylaw%20Final%20-%20AG%20Approved.pdf (See PDF pages 130-131)