4 Best ADU Builders in Boston, Massachusetts

Verified ADU contractors and builders in Boston, MA

Frequently Asked Questions — ADU Builders in Boston

How much does it cost to hire an ADU builder in Boston?

ADU construction costs in Boston, Massachusetts vary widely depending on size, type, and site conditions. Detached ADUs typically range from $150,000–$400,000+, while garage conversions and attached ADUs can be more affordable. Contact multiple builders in Boston to get accurate quotes for your specific project.

How long does it take to build an ADU in Boston?

In Boston, the ADU construction timeline typically ranges from 6 to 18 months from permit application to move-in. Permitting alone can take 2–6 months depending on Massachusetts local regulations. Prefab and modular ADUs often have faster timelines than site-built units.

Do I need a permit to build an ADU in Boston?

Yes, a building permit is required for ADU construction in Boston, Massachusetts. Your ADU builder will typically handle the permit application as part of their service. Massachusetts has adopted streamlined ADU permitting laws in recent years, which may reduce wait times.

What types of ADUs can be built in Boston?

Common ADU types in Boston include detached ADUs (backyard cottages), attached ADUs, garage conversions, basement conversions, and prefab/modular ADUs. The best type for your property depends on lot size, zoning, and budget. A local Boston ADU builder can advise on what's allowed on your specific parcel.