Concord, MA
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=