Are ADU permits faster or slower in Massachusetts than California?

Most non-California states haven't enacted statewide preemption laws like California's AB 881. That means ADU permits generally take longer in non-CA jurisdictions — Seattle, Portland, and Boston typically run 14–18 weeks vs California's 7–14 weeks.

What's special about Massachusetts ADU rules?

Check the city-specific notes below — each jurisdiction within the state may have unique impact fees, parking requirements, or design review processes.

ADU permits · Massachusetts

Massachusetts ADU permits: city-by-city in 2026

Permit fees, approval timelines, and ADU-specific rules across Massachusetts. Each city below has its own page with sourced data, including the planning-department URL we re-validate against each quarter.

Cities

City	Permit fees (all-in)	Timeline	Notes
Boston	$8,000 – $18,000	~18 wks	Massachusetts requires both owner-occupancy and parking replacement for most ADUs as of 2025–2026.

Massachusetts FAQ

Are ADU permits faster or slower in Massachusetts than California?: Most non-California states haven't enacted statewide preemption laws like California's AB 881. That means ADU permits generally take longer in non-CA jurisdictions — Seattle, Portland, and Boston typically run 14–18 weeks vs California's 7–14 weeks.
What's special about Massachusetts ADU rules?: Check the city-specific notes below — each jurisdiction within the state may have unique impact fees, parking requirements, or design review processes.

Get sourced ADU permit updates monthly