Newton, MA

Newton, MA Accessory Dwelling Unit (ADU) Rules

Last Updated 11/18/2025

Image source: Kenneth C. Zirkel

What You Need To Know

Newton, 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. Newton has general ADU rules as well as specific rules for detached and internal ADUs. These rules are outlined below.

Type of ADU Permit Required

ADUs in Newton 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

General ADU Rules in Newton:

  • ADUs can be attached, detached, or built within the main house (internal).

  • 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. 

  • Short-term rentals are not allowed. The minimum rental period for ADUs in Newton is 30 days.

  • The main house and ADU must be owned by the same person(s).

  • No more than 1 ADU is allowed per lot.

Detached ADU Rules in Newton:

  • Detached ADUs can be a maximum of 1,000 square feet, or half the Gross Floor Area of the main house; whichever is less. 

    • You can apply for a special permit for a 1,500 square foot detached ADU with the City Council.

Internal ADU Rules in Newton:

  • Internal ADUs can be a maximum of 1,000 square feet, or half the Gross Floor Area of the main house; whichever is less.

    • You can apply for a special permit for a 1,200 square foot internal ADU with the City Council.

Resources: 

https://www.newtonma.gov/home/showpublisheddocument/29823/638717834291930000

(See pages 132-135)

Attached ADU, Convert Existing SpaceGuest UserGreater Boston, Friendliness score 10/10, Newton, Massachusetts