Fitchburg, MA
Fitchburg, MA Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 7/10 (10 is most accepting)
Last updated: 8.28.2024
Source: City of Fitchburg
What You Need To Know
Currently not in compliance with the Massachusetts Affordable Homes Act.
ADUs are allowed only within or attached with minimal impact to the existing single family home. ADUs are permitted in a limited number of zoning districts.
Type of ADU Permit Required
ADUs are allowed by right via a building permit in the Rural Residential (RR) and Residence A (RA), but in zoning district Residence B (RB) ADUs require a special permit.
ADU Rules
A plan from a registered land surveyor must be submitted to the building commissioner that includes the existing dwelling, the proposed location of the ADU, location of any septic system, and required parking.
The ADU must be occupied by the owner of the property except for a bona fide temporary absence.
This has to be certified by an affidavit.
Not more than one ADU is allowed per lot.
The ADU cannot be greater than 800 square feet of habitable floor space.
The ADU must be within the primary structure.
The external appearance of the existing dwelling cannot be significantly altered from the appearance of a single family home.
The ADU cannot result in an increase of more than 15% in the habitable and non-habitable floor area of the existing dwelling.
Any stairways must be within or screened in.
One additional parking space must be provided for the ADU
Special permits for ADUs are issued by the board of appeals only after the construction and occupancy of one is not detrimental to the neighborhood.
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)
Concord, MA
Concord, MA allows ADUs up to 750 sq. ft. by right.
Concord, MA Accessory Dwelling Unit (ADU) Rules
Last Updated: 3/1/2026
Image source: Visit Concord
What You Need To Know
Concord, like all Massachusetts communities following the 2024 Affordable Homes Act, allows ADUs by right under the state framework. Concord has since updated its local ADU rules to align with that law and now allows ADUs of up to 1,000 square feet by right, which is more permissive than the state minimum. The key local rules for Concord are outlined below.
Type of ADU Permit Required
ADUs are now allowed up to 1000 square feet by submitting a building permit.
ADU Rules in Concord:
Your ADU can be up to 1,000 square feet, not counting garage space. If state rules allow a larger measurement method, that larger standard applies.
You can have only one ADU on the lot.
The ADU has to follow the same setback and placement rules that apply to the main house in that zoning district. In simple terms, it has to sit on the lot where a primary home would normally be allowed to sit.
You need to provide one parking space for the ADU, unless the property is within half a mile of a transit stop, in which case no extra parking space is required.
The ADU cannot be split off or sold separately from the main house. It must stay part of the same property.
The ADU must stay within the height limits that apply in that zoning district.
Neither the main house nor the ADU can be used as a bed and breakfast or tourist home.
Resources:
https://www.concordma.gov/DocumentCenter/View/54012/Article-XX-Section-4222-ADU-Bylaw-2-11-25-Final?bidId=
Shutesbury, MA
Shutesbury revised its rules for Accessory Dwelling Units in 2008 to make it easier for homeowners to add an additional dwelling unit to their properties. The city sees ADUs as a great to way help increase density and create high quality housing without sacrificing the character of the town. Since the bylaw was approved, there have been many ADUs added to homes including at least one backyard home (detached ADU)!
Shutesbury, MA Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 7/10 (10 is most accepting)
What you need to know:
Shutesbury revised its rules for Accessory Dwelling Units in 2008 to make it easier for homeowners to add an additional dwelling unit to their properties. The city sees ADUs as a great to way help increase density and create high quality housing without sacrificing the character of the town. Since the bylaw was approved, there have been many ADUs added to homes including at least one backyard home (detached ADU)!
Type of Permit Required:
Shutesbury allows both attached and detached ADUs by right with a site plan review by the Zoning Board of Appeals.
ADU rules in Shutebury:
The property must have slightly more than 1 acre (45,000 SF, 1.03 acres).
The primary home and proposed ADU must follow the district’s setback requirements.
One of the two dwelling units must be owner occupied.
An ADU can only be added to a single family property.
No additional curb cuts can be created. Access to the ADU must be provided from an existing driveway or access road to the property.
See the full text here: Zoning Ordinance, Section: 4.4-2 Accessory Apartments
Chesterfield, MA
Chesterfield joined many cities in MA by revising its zoning bylaw to make it easier for homeowners to build accessory apartments in most zoning districts.
Chesterfield, MA Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 7/10 (10 is most accepting)
What you need to know:
Chesterfield joined many cities in MA by revising its zoning bylaw to make it easier for homeowners to build accessory apartments in most zoning districts.
Type of Permit Required:
Conversion of Existing Space or Attached:
By right in:
Town Center
Agricultural Residential I
Agricultural Residential II
By Special Permit in the following overlay districts:
Floodplain
Westfield River Protection District
Water Supply Protection District
Special permits are also required if an apartment is being added to a commercial building.
Detached ADUs:
A Special Permit is always required for detached ADUs.
ADU Rules in Chesterfield:
The ADU must be a fully separate dwelling unit with its own kitchen, bath, and egress.
A lot can only have one accessory apartment.
The ADU must have 2 or fewer bedrooms.
At least two additional off-street parking spaces shall be provided for the ADU. Parking spaces shall be located on the side or rear of the building to the extent feasible.
The ADU’s appearance must match the character of the original building.
New entrances shall be located on the side or rear of the building to the extent feasible.
The ADU must be subordinate to the primary building.
The living area shall not be more than 33% of the existing residential living space (commercial building SF) or 800 square feet, whichever is less.
Small homes or commercial buildings, can bypass the 33% limitation and build a 300 square feet ADU.
Read the full bylaw here: Zoning Ordinance, Section 6.1 Accessory Apartments