Planning board urges city council to postpone ADU hearing until state issues final guidance

The Chelsea Planning Board voted to ask the city council to postpone a hearing on a draft accessory dwelling unit (ADU) zoning amendment until final state guidance is issued, saying key technical questions about measurement, parking, dimensional limits and municipal utility capacity remain unresolved.

William of the Department of Permitting and Planning summarized the draft as an effort to align local rules with the state’s Affordable Homes Act. The staff-drafted amendment would allow one ADU per lot by right in single-family zoning districts, prohibit short-term rentals of ADUs as defined in state law, limit ADU size to one-half of a principal dwelling’s gross floor area or 900 square feet (whichever is smaller), require design review by the planning department, and trigger a minor site plan review for new ADUs. Staff noted the city was awaiting final guidance from the Executive Office of Housing and Livable Communities and that draft guidance was recently released on Dec. 6.

Board members pressed staff on how gross floor area would be calculated for conversions (attics, basements), whether assessor or drawing-backed measurements would be required, how the change intersects with building-code and setback rules, and whether municipalities may legally impose owner-occupancy or bedroom/occupant limits. Staff responded that the state defines gross floor area, building-code requirements remain applicable for habitability, and the state views owner-occupancy restrictions as likely unreasonable. Members also raised concerns that many Chelsea lots are small—limiting opportunities for ADUs—and that infrastructure capacity (water, sewer, electrical) and parking impacts should be assessed before the city sets local rules.

Given those outstanding technical and cross-departmental questions, the planning department recommended and the board voted to recommend that the city council postpone its hearing on the draft ADU amendment until the state finalizes guidance so the city can incorporate that guidance and consult DPW, the building inspector and other departments as needed.

The board’s recommendation is advisory; the next step is a city council hearing in which councilors will consider the draft amendment and any revisions the planning staff proposes after state guidance and interdepartmental review.