Local Politics
  1. Home
  2. US
  3. Massachusetts
  4. Somerville
  5. Issues

Backyard Cottage Zoning Rules

At a glance

  • What: Zoning changes for backyard cottages, now called Accessory Dwelling Units (ADUs) under state law: how big they may be, what they may be attached to, lot splits and inclusionary requirements.
  • Where it stands: In committee. On Thursday, October 15, 2026 the Land Use Committee discussed a Mayor's amendment (26-1336) to align with state law on protected ADUs and kept it in committee. Earlier stages (May and June 2026) are older meetings.
  • Next: Councilor Ewen-Campen will work with staff on amendment language for a later committee meeting; Councilor McLaughlin and President Davis requested further information (below).

October 15, 2026 Land Use Committee

  • Dan Bartman, Director of Planning and Zoning, said the amendments would bring local rules into compliance with state ADU rules (ADUs within existing buildings or detached) and that current City rules have produced larger backyard cottages than anticipated.
  • Members worried about size and height, setbacks, tenant displacement and stormwater. President Davis, Councilor McLaughlin, Councilor Clingan and Councilor Sait supported ADUs but wanted rules closer to the original intent of smaller cottages.
  • Councilor McLaughlin asked for a City Solicitor opinion on state ADU requirements plus data on demolitions, condominium conversions and tenant displacement protections. President Davis asked for review of basement square footage calculations and the green score requirements.
  • Councilor Ewen-Campen proposed cutting the maximum ADU size to 1,152 square feet, limiting height to 1.5 stories and counting basement space in the total. Result: kept in committee (no roll call recorded).
  • The same committee advanced a terminology change renaming "Affordable Dwelling Units" to "Price-Restricted Dwelling Units" so the acronym ADU matches state use (see Zoning Housekeeping Amendments).

Earlier: May and June 2026

  • On May 28, 2026 Councilor Ewen-Campen reported that the Land Use Committee (May 21) had discussed four amendments: reduce the allowable size of backyard cottages; legally make a cottage an accessory to one of the other units; require public hearings and Zoning Board approval for a lot split; and apply the City's 20 percent inclusionary rule to any lot split that creates more than five units. The report was approved. Twenty-seven residents submitted comments on the related zoning text amendments (26-0328, 26-0329, 26-0330), which were sent to the Land Use Committee.
  • On June 25, 2026 the Planning Board's recommendations on those items (26-0971, covering 26-0328, 26-0329 and 26-0330 among others) were placed on file, and the Land Use Committee also met in joint session with the Planning Board on June 18.

Sources

Log

2026-10-15 - Land Use Committee

ADU compliance amendment (26-1336) discussed at length and kept in committee; Councilor Ewen-Campen proposed a 1,152 square foot cap and 1.5 stories.

2026-06-25 - City Council

Planning Board recommendations on the backyard cottage zoning text amendments placed on file.

2026-05-28 - City Council

Land Use Committee report on four backyard cottage amendments approved; 27 residents' comments referred to the Land Use Committee.

2026-10-08 - City Council Regular Meeting

The Land Use report described a joint hearing with the Planning Board. Staff read state rules as barring stricter local limits on accessory dwelling units than on the main building; the mayor's proposal is 1,750 square feet against a state floor of 900.