Massachusetts ADU Laws

Complete 2026 guide to accessory dwelling unit regulations

Strong Statewide Law

📋Quick Facts

Max Size
900 sq ft
Owner Occupancy
✓ Not required
Parking
✓ Limited by state
Approval Process
✓ By-right
Effective Date
8/6/2024

📜Recent Legislation

Chapter 150 of Acts of 2024 (Section 8) - Statewide ADU by-right in single-family zones

⚠️Key Requirements & Restrictions

  • Under 900 sqft for by-right

📖Detailed Analysis

Major reform in 2024 allowing ADUs by-right in single-family zones statewide for units under 900 sqft.

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⚠️ Disclaimer

The information provided on this website is for general informational purposes only and does not constitute legal, financial, or professional advice. ADU laws, regulations, and requirements vary by jurisdiction and change frequently. While we strive to keep this information accurate and up-to-date, we make no representations or warranties of any kind about the completeness, accuracy, reliability, or suitability of this information. Always consult with qualified local professionals, including attorneys, architects, and your local planning department, before making any decisions regarding ADU construction or investment. Use of this information is at your own risk.

ADU Tools by MassDwell

Last updated: February 2026