[Amended 3-22-2025 ATM by Art. 23]
A.
Purpose and intent. The intent of permitting accessory dwelling units is to:
(1)
Develop housing units in single-family neighborhoods that are appropriate for households at a variety of stages in their life cycles.
(2)
Protect stability, property values, and preserve the residential character of a neighborhood.
(3)
Add moderately priced rental units to the housing stock to meet the needs of smaller households and make housing units available to moderate income households who might otherwise have difficulty finding housing.
(4)
Legitimize prior accessory dwelling unit conversions and enable the Town to monitor conversions for code compliance.
B. ACCESSORY DWELLING UNIT (ADU)
Definition. As used in this section, an accessory dwelling unit shall have the meaning indicated:
A self-contained housing unit, inclusive of sleeping, cooking and sanitary facilities on the same lot as a principal dwelling, subject to otherwise applicable dimensional and parking requirements, that: i) maintains a separate entrance, either directly from the outside or through an entry hall or corridor shared with the principal dwelling sufficient to meet the requirements of the state building code for safe egress; ii) is not larger in gross floor area than 1/2 the gross floor area of the principal dwelling or 1,000 square feet, whichever is smaller; and iii) is subject to such additional restrictions as may be imposed by a municipality, including, but not limited to, additional size restrictions and restrictions or prohibitions on short-term rental, as defined in of MGL c. 64G, § 1. An ADU shall not be considered an accessory building as defined in § 1.6 or an accessory structure as described in footnote (g) of § 5.4 of the Zoning Bylaw.
C.
Requirements. The Building Commissioner may issue a building permit authorizing the construction and use of an accessory dwelling unit within a lawful existing or new principal dwelling to which the ADU is accessory, or in a new or existing detached building accessory to and on the same lot as the principal dwelling subject to the following:
(1)
An ADU that conforms to the requirements contained herein shall be permitted by right as an accessory use on any lot within a zoning district where single-family residential uses are allowed.
(2)
The ADU may be a detached dwelling on the same lot or part of the same structure as the primary dwelling unit.
(3)
Except as may be allowed by the issuance of a special permit, an ADU shall not be larger in gross floor area than 1/2 the gross floor area of the principal dwelling or 1,000 square feet, whichever is smaller.
(4)
No more than one accessory dwelling unit shall be provided on a single lot.
(5)
An accessory dwelling unit shall not be used as a short-term rental as defined in MGL c. 64G, § 1.
(6)
The construction of any accessory dwelling unit must be in conformity with the federal, state, and local laws and regulations.
(7)
An accessory dwelling unit must remain an accessory use to the principal dwelling with which such accessory dwelling unit is associated.
D.
Dimensional and parking requirements.
(2)
In addition to the minimum parking required for the principal dwelling, one additional off-street parking space shall be available for use by the occupant(s). If the ADU is located within 0.5 mile of the MBTA Commuter Rail Station, off-street parking spaces shall not be required.
E.
Accessory dwelling unit by special permit. An ADU not conforming to the provisions of § 7.1C may be permitted upon issuance of a special permit by the Zoning Board of Appeals subject to the following provisions: