Massachusetts ADU Laws & Rules (2026)

Compare ADU zoning rules across 3 Massachusetts cities. Average ADU score: 6.3/10.

ADU-by-Right (2024)

Key Massachusetts ADU Laws

Massachusetts ADU Laws

  • ADU-by-right (2024): All single-family zones must allow ADUs
  • Streamlined permitting for municipalities statewide
  • No special permits required in most communities
  • Size limits and setbacks vary by municipality

Massachusetts Cities ADU Comparison

CityMax SizeSetbacksPermit FeesBuild Cost1BR RentScore
Boston 900 sq ft 20 feet $4,500-$7,500 $200,000-$400,000 $1,800-$2,400/mo 6/10
Cambridge 950 sq ft 15 feet $3,500-$5,500 $210,000-$420,000 $1,900-$2,500/mo 7/10
Worcester 850 sq ft 20 feet $2,800-$4,500 $140,000-$280,000 $1,250-$1,650/mo 6/10

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