Somerville Housing and Zoning Glossary

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Folks use a LOT of jargon and acronyms in housing policy, and a lot of terms are specific to Somerville as well. Here’s a list of some of them. If you have questions or suggestions, please let us know at steering@somervilleyimby.org.

Somerville Land Use People & Processes

In Somerville, the Planning Board is an appointed advisory group that helps the city guide planning decisions and special permits. The Zoning Board of Appeals is an appointed advisory group that focuses on exceptions to the usual zoning rules. The Land Use Committee is composed of City Council members who make and/or influence the full City Council’s decisions on major land use decisions including the zoning ordinance.

The approximate process of changing part of the zoning ordinance is:

  1. Petition or council order is filed
  2. The Planning Board debates it and make a recommendation on it (positive, negative, or neutral)
  3. The Land Use Committee will discuss that recommendation and make their own recommendation to the council as a whole
  4. City Council as a whole debates & can vote to adopt (two sets of votes are generally needed)
  5. Proposal goes to the mayor to be signed into law

Somerville-specific zone abbreviations:

  • MR: Our midrise zone, from MR3 at three stories to MR6 at six stories. Both housing and commercial activities are allowed here.
  • NR: Neighborhood Residence. Our less dense residential zone. Generally 1 or 2 family homes, with a handful of tightly-restricted triple deckers. Most of the city is zoned NR.
  • UR: Urban Residence: Our more dense residential zone, from 4-plexes to apartment buildings.

Those three cover the vast majority of the city. Less common zones include Commercial Core (CC, for commercial use only, 3-6 stories like MR), High Rise (HR, anything taller than 6 stories), and Civic (city buildings, parks, etc).

There are also overlay districts, which modify the base in certain ways. The most important of these is the Affordable Housing Overlay (AHO) which grants some bonuses & accelerated permitting to builders of 100% affordable housing in NR, UR, and MR districts.

Common policy terms and abbreviations

  • ADU: Accessory dwelling unit. AKA “in-law apartment” or “granny flat.” (Not to be confused with affordable dwelling unit).
  • AMI: Area median income. See “What Exactly Do We Mean by Affordable Housing?” for details on how this is calculated in the greater Boston area.
  • By-right: Allowed without a special permit. E.g. “In the current zoning ordinance, household living is allowed in MR districts by special permit, but we’d like to see it allowed by right.”
  • In-lieu fee: A fee paid to the city instead of providing apartments under IZ rules. These are discouraged in Somerville but are used when a building is required to provide a percentage of a home.
  • IZ: Inclusionary zoning. A requirement to have some affordable housing in a new building. Somerville sets this at 20%. Learn more about inclusionary zoning.
  • Linkage fee: A fee charged to developers to cover the cost of public services provided to new development. (See Wikipedia for details. For commercial developments over 30,000 square feet, developers must contribute $2.93 per square foot to the city’s job creation & retention program and $22.46 per square foot to the affordable housing trust fund.
  • MBTA-C: MBTA Communities Law, requiring cities served by the MBTA to zone for housing growth. A complex and controversial law even in Somerville. Also known as Section 3A. The Boston Globe has a good explainer on what that means for different cities near Boston.
  • “Priced at X% AMI” or “Affordable at 80%”: Inclusionary affordable housing units are rented at a cost that’s roughly 30% of the targeted household income. An apartment “priced at 80%” might be for a family of three making about $80,000 per year, and rent at 30% of that income, or $2,000 a month.
  • ZBA: Zoning Board of Appeals. An appointed board in most cities that allows certain deviations from zoning rules for reasons including economic hardship.

Somerville-specific rules that get talked about a lot

  • ADUs in NR: Somerville allows duplexes in Neighborhood Residence to add a third unit, but only if it’s designated affordable (at 110% of AMI). City Council is planning to change the rules to make third units in NR financially viable in late 2023.
  • Triple-deckers in NR: The 2019 zoning overhaul went back and forth about this, but the city eventually decided not to allow triple-deckers to be built in Neighborhood Residence zones except in certain very specific situations. City Council is set to make triple-deckers much easier to build in late 2023.
  • More Than Four Unrelated: In an effort to stop students from noisily living together, Somerville bans more than four unrelated people living together in one residence without a boarding house permit. City Council planning to eliminate this rule in 2023.
  • Somerville Climate Forward: Our climate change plan.
  • SomerVision 2040: Our long-term comprehensive plan, which includes goals for creating housing and reducing car use.