Cambridge planning board backs allowing multifamily citywide, urges council to refine height, setback and review rules

The Cambridge Planning Board on Dec. 17 backed the goal of allowing multifamily and townhouse residences citywide while urging the City Council to refine the language of two zoning petitions to address heights, setbacks, review thresholds and potential loss of private‑lot tree canopy.

Chair Mary Flynn said the board ‘‘support[s] the idea of ending the exclusionary zoning, and having multifamily allowed citywide’’ but that members had ‘‘a variety of opinions on the 6 stories’’ and wanted the Council to consider amendments. The board voted 6‑0 to concur with the chair’s summary and ask the Council to incorporate the board’s suggested changes; Tom Sinevich moved the motion and Ted Cohen seconded.

The action followed a staff presentation by Melissa (Community Development staff) comparing six rezoning scenarios and a separate squares‑and‑corridors analysis. Melissa described the modeling as ‘‘a planning‑level analysis’’ meant to compare options rather than predict specific projects, and explained the team’s redevelopment rules (a GFA‑delta greater than 4,000 square feet and a GFA‑delta/existing ratio above 33% for residential sites; different thresholds for corridors) and an assumption of 1,000 square feet per unit.

Under the scenarios shown to the board, a six‑story as‑of‑right residential approach produced the largest number of new units in the residential districts (about 1,630 additional units by 2030 in the residential areas alone). The corridors and squares scenarios—where staff tested higher heights on major streets and nodes—generated larger totals: roughly 4,900 units by 2030 (about 830 affordable) and roughly 12,425 units by 2040 (about 1,940 affordable) in the squares/corridors model. Melissa cautioned the numbers are sensitive to assumptions about redevelopment incentives and funding timing.

Board members who spoke agreed with the petitions’ intent to increase housing stock and incentivize inclusionary projects but were split on implementation. Some members favored allowing up to six stories broadly to increase production; others preferred a citywide four‑story baseline with a two‑story bonus tied to inclusionary projects, or a system that allows greater height only on larger lots or in corridors. Several members urged clearer rules to avoid ‘‘McMansion’’‑style outcomes and to preserve sunlight, livability and private green space.

Multiple members asked the Council to require or study minimum side and rear setbacks, to examine how much private‑lot canopy might be lost under the proposed reductions in lot‑line setbacks, and to identify mitigation options (public open space, canopy‑planting programs or other strategies). Mary Liedecker flagged a potential conflict with the Urban Forest Master Plan and asked for more analysis of canopy impacts.

Legal and implementation questions also surfaced. City Solicitor Megan Baier said zoning already contains different dimensional rules by use and suggested overlay tools or amendments to the inclusionary ordinance could be used to craft incentives; staff noted the petitions in front of Council could be amended and that the precise drafting would determine whether re‑filing was required.

On process, staff described existing project‑review thresholds (project review currently triggers at 50,000 square feet citywide and at lower thresholds in some corridors) and the pending petition’s proposed changes for housing thresholds; members discussed the tradeoff between faster as‑of‑right building and the loss of discretionary review that can require design adjustments and sometimes prevent lengthy appeals.

The board’s motion asked the Council to proceed with the policy intent of permitting multifamily uses citywide while taking seriously the planning board’s suggested refinements regarding heights, setbacks, review paths, incentives for truly additional units (for example, tying height bonuses to increased unit counts), and a study of canopy/open‑space impacts. Jeff Roberts (Director of Zoning and Development) will attend the City Council ordinance committee meeting and convey the board’s positions; a written recommendation from the board will follow.

The City Council ordinance committee has hearings scheduled Dec. 19 and Jan. 8; the Council could act on amendments in the weeks afterward. The Planning Board adjourned for the year and will reconvene in January.