Definitions

Accessory Dwelling Unit (ADU). 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: (a) 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 Building Code for safe egress; (b) is not larger in Gross Floor Area than ½ the Gross Floor Area of the Principal Dwelling or 900 square feet, whichever is smaller; and (c) 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 M.G.L. c. 64G, § 1; provided, however, that no Municipality shall unreasonably restrict the creation or rental of an ADU that is not a Short-term Rental. Building Code. The Massachusetts state building code, 780 CMR. Bus Station. A location serving as a point of embarkation for any bus operated by a Transit Authority. Commuter Rail Station. Any commuter rail station operated by a Transit Authority with year-round service with trains departing at regular time intervals, rather than intermittent, seasonal, or event-based service. (Mass. Register #1540, 1/31/2025) Design Standards. Clear, measurable and objective provisions of Zoning, or general ordinances or by-laws, which are made applicable to the exterior design of, and use of materials for an ADU. Dwelling Unit. A single housing unit providing complete, independent living facilities for one or more persons, including permanent provisions for living, sleeping, eating, cooking and sanitation. EOHLC. The Executive Office of Housing and Livable Communities. Ferry Terminal. The location where passengers embark and disembark from a ferry service with year-round service with ferries departing at regular time intervals, rather than intermittent, seasonal, or event-based service. Fire Code. The Massachusetts state fire code, 527 CMR 1.00: Massachusetts Comprehensive Fire Safety Code. Gross Floor Area (GFA). The sum of the areas of all stories of the building of compliant ceiling height pursuant to the Building Code, including basements, lofts, and intermediate floored tiers, measured from the interior faces of exterior walls or from the centerline of walls separating buildings or dwelling units but excluding crawl spaces, garage parking areas, attics, enclosed porches and similar spaces. Where there are multiple Principal Dwellings on the Lot, the GFA of the largest Principal Dwelling shall be used for determining the maximum size of a Protected Use ADU. Historic District. A district in a Municipality established pursuant to M.G.L. c. 40C or other state law that is characterized by the historic or architectural significance of buildings, structures, and sites, and in which exterior changes to and the construction of buildings and structures are subject to regulations adopted by the Municipality pursuant to M.G.L. c. 40C or other state law. Lot. An area of land with definite boundaries that is used, or available for use, as the site of a structure, or structures, regardless of whether the site conforms to requirements of Zoning. Modular Dwelling Unit. A pre-designed Dwelling Unit assembled and equipped with internal plumbing, electrical or similar systems prior to movement to the site where such Dwelling Unit is affixed to a foundation and connected to external utilities; or any portable structure with walls, a floor, and a roof, designed or used as a Dwelling Unit, transportable in one or more sections and affixed to a foundation and connected to external utilities. Municipality. Any city or town subject to the provisions of M.G.L. c. 40A. Principal Dwelling. A structure, regardless of whether it, or the Lot it is situated on, conforms to Zoning, including use requirements and dimensional requirements, such as setbacks, bulk, and height, that contains at least one Dwelling Unit and is, or will be, located on the same Lot as a Protected Use ADU. Prohibited Regulation. Zoning or general ordinances or by-laws, or Municipal regulations that are prohibited pursuant to 760 CMR 71.03(2). Protected Use ADU. An attached or detached ADU that is located, or is proposed to be located, on a Lot in a Single-family Residential Zoning District and is protected by M.G.L. c. 40A, § 3, provided that only one ADU on a lot may qualify as a Protected Use ADU. An ADU that is nonconforming to Zoning shall still qualify as a Protected Use ADU if it otherwise meets this definition. Short-term Rental. Short-term rental, as defined in M.G.L. c. 64G, § 1. Single-family Residential Dwelling. A structure on a Lot containing not more than one Dwelling Unit. Single-family Residential Zoning District. Any Zoning District where Single-family Residential Dwellings are a permitted or an allowable use, including any Zoning District where Single- family Residential Dwellings are allowed as-of-right or by Special Permit. Site Plan Review. A process established by local ordinance or by-law by which a Municipal board or authority may review and impose terms and conditions on, the appearance and layout of a proposed use of land or structures prior to the issuance of a building permit. Special Permit. A permit issued by a Municipality’s special permit granting authority pursuant to M.G.L. c. 40A, § 9. Subway Station. Any of the stops along the Massachusetts Bay Transportation Authority Red Line, Green Line, Orange Line, Silver Line, or Blue Line, including any extensions or additions to such lines. Transit Authority. The Massachusetts Bay Transportation Authority established by M.G.L. c. 161A, § 2 or other local or regional transit authority established pursuant to M.G.L. c. 161B, § 3 or M.G.L. c. 161B, § 14. Transit Station. A Subway Station, Commuter Rail Station, Ferry Terminal, or Bus Station. Unreasonable Regulation. Zoning or general ordinances or by-laws, or Municipal regulations that are unreasonable pursuant to 760 CMR 71.03(3). Use and Occupancy Restrictions. A Zoning restriction, Municipal regulation, covenant, agreement, or a condition in a deed, zoning approval or other requirement imposed by the Municipality that limits the current, or future, use or occupancy of the Protected Use ADU to individuals or households based upon the characteristics of, or relations between, the occupants, such as but not limited to, income, age, familial relationship, enrollment in an educational institution, or that limits the number of occupants beyond what is required by applicable state code. Zoning. Ordinances and by laws, including base, underlying, and overlay zoning, adopted by cities and towns to regulate the use of land, buildings and structures to the full extent of the independent constitutional powers of cities and towns to protect the health, safety and general welfare of their present and future inhabitants. Zoning District. A geographic area within a Municipality which, pursuant to Zoning, is subject to use and structure requirements that are uniform within the area.