Can You Build an ADU on Your Property?
Find out in 30 seconds — free.
Search your Massachusetts town to see setbacks, fees, timelines, and what you can build under the new state ADU law.
📍 All 351 Massachusetts municipalities covered
How It Works
Search Your Town
Type your Massachusetts town name above
See Requirements
Get setbacks, fees, timelines, and rules specific to your town
Start Planning
Know exactly what's possible before you talk to a builder
🏠 What Changed: MA ADU Law (August 2024)
Massachusetts passed the Affordable Homes Act in August 2024, making it significantly easier to build an ADU (Accessory Dwelling Unit) on your property.
✅ What the New Law Guarantees
- •ADUs under 900 sqft are now allowed by-right statewide
- •Towns cannot prohibit ADUs on single-family lots
- •Maximum 1 parking space can be required
- •No special permit needed for compliant ADUs
⚠️ What Towns Still Control
- •Setback requirements (distance from property lines)
- •Design standards (height, appearance)
- •Owner-occupancy rules (varies by town)
- •Permit fees and timelines
That's why this tool exists — while the state law provides a baseline, every town has different local requirements. Search your town above to see the specifics.
Why Use the ADU Permit Navigator?
Save Hours of Research
Stop digging through town websites and zoning bylaws. Get the key info in seconds.
Direct Building Dept Contacts
Get the right phone number and email to confirm requirements before you start.
Know Costs Upfront
See estimated permit fees and typical timelines before committing to a project.
Understand Setbacks
Learn exactly how far from property lines you need to build in your town.
🧰 Free ADU Planning Tools
Planning your ADU project? Use our free tools to calculate ROI and track your progress.
Frequently Asked Questions
What is an ADU?
An Accessory Dwelling Unit (ADU) is a secondary housing unit on a single-family residential lot. It can be a detached backyard cottage, an attached addition, or a conversion of existing space (like a garage or basement).
Can I build an ADU anywhere in Massachusetts?
Under the 2024 Affordable Homes Act, ADUs up to 900 sqft are now allowed by-right on any single-family lot in Massachusetts. However, you still need to meet your town's setback, height, and design requirements.
How much does an ADU cost to build?
ADU costs in Massachusetts typically range from $150,000 to $350,000+ depending on size, finishes, and site conditions. Modular/prefab ADUs can offer faster timelines and more predictable pricing.
Do I need to live in my home to have an ADU?
Owner-occupancy requirements vary by town. Some towns require you to live in either the main house or the ADU. Use this tool to check your town's specific rules.
How long does it take to get an ADU permit?
Permit timelines vary significantly by town — from 2 weeks in streamlined towns to 3+ months in others. This tool shows typical timelines for your specific town.
Ready to Build Your ADU?
MassDwell is Massachusetts' premier modular ADU builder. We handle permitting, design, and construction — from start to finish in 8-12 weeks.