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)