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)