Arlington Zoning Dictionary

The purpose for which a structure or lot is designed or intended to be used, occupied, or maintained. A few example uses are residential, retail, restaurant, and business/professional/medical office.

A combination of materials for permanent or temporary occupancy or use. A few example structures are buildings, retaining walls, swimming pools, fences, signs, and sheds.

An ADU is a separate, smaller living unit with its own kitchen and bathroom facilities and separate entrance that is attached to or included within a larger residence or located in an accessory structure on the same lot as a larger residence.

Since 2021, Arlington’s zoning bylaw (Section 5.9.2) has allowed ADUs by right for both single and two-family dwelling units. An ADU must be the lesser of 900 sq. ft or half the square footage of the principal dwelling and cannot be built by a developer or used as a short-term rental.

In Arlington, a single building that contains two homes can be either a “two-family dwelling” or a “duplex.” A two-family dwelling has one home stacked above the other, at least in part. A duplex can be either two homes that are side-by-side or two homes that are front-to-back.

A combination of two or more distinct uses in a single structure, such as a building with retail on the ground floor and housing on the upper floors. Mixed-use development may promote a vibrant, pedestrian-oriented living and working environment. Arlington’s Master Plan prioritizes mixed-use buildings, which are authorized by Arlington’s Zoning Bylaw subject to a Special Permit and Environmental Design Review.

Multi-family housing can have different meanings. Under Arlington’s Zoning Bylaw, “multi-family housing” refers to a building containing four or more residences. The State Housing Choice legislation, however, defines “multifamily” (in part) as a building with three or more dwelling units. Note that under state Housing Choice legislation, ADUs do not count towards the number of dwellings in a multi-family building.

A condition that occurs when a lot, building, or land use that legally existed before current zoning requirements does not conform to one or more current requirements, such as dimensional requirements. Most of Arlington’s homes were built prior to the contemporary zoning requirements, and the majority of residential houses or lots are nonconforming in some way.

If someone wants to add to a house or lot that is non-conforming, they may do so provided that no new non-conformities are created and the ZBA determines that the change is not substantially more detrimental to the neighborhood.

Parking minimums are local laws that require private businesses and residences to provide off-street parking spaces. In Arlington, most dwelling units (houses, condos, apartments, etc.) are required to have at least one parking space per unit. Before the 2022 Town Meeting, Arlington required more than one parking space per unit in apartment buildings. Cities around the US, ranging from Sacramento and South Bend to Cambridge, MA, have been removing minimum parking requirements entirely.

What we consider “regular zoning” is established under MGL Chapter 40A. This chapter authorizes cities (other than Boston) and towns to establish local zoning rules and sets standards for their administration.

Adapted from CHAPA.

Informally known as the “Anti-snob zoning act” at the time of its passage in 1969, Chapter 40B is also known as the Comprehensive Permit Law. It was enacted to expand where low- and moderate-income households can afford to live by reducing regulatory barriers to building affordable housing. In the 2010 state-wide referendum, Arlington voted overwhelmingly in favor (64% to 36%) of preserving 40B in Massachusetts.

Chapter 40B empowers the Zoning Board of Appeals (ZBA) to waive certain town zoning and other requirements for projects where at least 20%-25% of the units have long-term affordability guarantees. In towns where less than 10% of housing or 1.5% of land qualifies for the Massachusetts Subsidized Housing Inventory (SHI), there is a strict review of the 40B decisions by the state and the town has less authority over its decisions. Currently only 6.54% of Arlington’s housing is listed on the SHI, even though the town is close to meeting the 1.5% land area standard.

Adapted from MAPC:

Housing Choice refers to a number of changes to the state’s zoning law, MGL Ch. 40A that were enacted in January, 2021 as part of the Economic Development Bond Bill (H.5250). Final guidance for implementing the law was released in 2022.

The law makes major changes to zoning statues in three categories:

• Elimination of the 2/3 vote for certain zoning changes related to housing production, allowing instead a majority vote to adopt those zoning changes;
• Multifamily zoning requirements for MBTA municipalities; and
• Other changes to streamline permitting and discourage meritless legal challenges, including reducing from ⅔ voting for certain special permits to a majority vote instead.

Under the Housing Choice Law passed in 2021, 175 Massachusetts cities and towns that host or are near an MBTA service are defined as MBTA Communities. Thanks to its proximity to the Red Line at Alewife, Arlington counts as an “adjacent community.” Adjacent communities must have at least one zoning district of reasonable size that allows multi-family housing by right, among other criteria. Arlington will lose eligibility for certain state grants if it is noncompliant.

A lot on which housing can be built given the existing footprint, lot size, setbacks, height, and open space requirements. In contrast, a non-buildable lot is a lot in which some restriction or combinations or restrictions makes building impossible on that particular lot.

Gross Floor Area (often abbreviated GFA) is “the sum of the horizontal areas of all stories of a building or buildings measured from the exterior faces of exterior walls, or in the case of a common wall separating two buildings, from the centerline of such common wall”. It’s roughly the interior area of a building, plus the space occupied by the building’s walls.

GFA can include both finished and unfinished interior areas. There are many rules outlining what areas to include and exclude; these rules can be found in Section 5.3.22 of the Zoning Bylaw.

Floor Area Ratio is the gross floor area of buildings on a lot divided by the total area of the lot (GFA/Lot Area). For example, a building with a FAR of 2 could be:

• a two-story building covering the entire lot,
• a four-story building covering half the lot, or
• many other variations with the same gross floor area.

Required distance between building and lot edge.

• Front yard setback: distance between the building’s front façade and the front lot line, or lot line along the street.
• Side yard setback: distance between the building and the side lot lines, or the lot lines perpendicular to the street.
• Rear yard setback is the distance between the building and the rear lot line.

Arlington’s zoning bylaw defines two types of open space. First, there are open space districts, which are generally owned by state or town entities, available to the general public, and provide for various conservation and recreation uses. Second there are open space regulations, which apply to the portions of a lot that aren’t occupied by buildings, and not used for parking or vehicular traffic. The formal definition of this kind of open space is “A yard including sidewalks, swimming pools, terraced areas, decks, patios, play courts, and playground facilities; and not devoted to streets, driveways, off-street parking or loading spaces,or other paved areas.” Open space regulations are based on a percentage of gross floor area, so they partially regulate building size and massing, similar to FAR.

The predominant kind of open space required by Arlington’s zoning is Usable Open Space, which must be generally flat, and measure at least 25’ in each direction. This requirement was added to the zoning bylaw in 1975 and a significant number of smaller residential lots do not comply with it.