Can you actually build an ADU here?

Massachusetts made ADUs legal by right in 2025. That does not mean every lot works. Answer six questions and see your real size cap, whether septic is going to be the problem, and what it is likely to cost.

Your property

Property address (optional) Only used to show you a satellite view of your lot. Skip it if you'd rather not.

Which town is the property in?

Is the property on municipal sewer or septic? This is the single biggest factor. If you are not sure, pick "Not sure".

Roughly how big is the main house? Used to calculate your legal size cap.

The plan

How many bedrooms in the main house?

How many bedrooms in the ADU?

What are you picturing?

Want the full picture?

This is a first-pass read. Our guide to accessory dwelling units in Massachusetts covers the by-right rules, Title 5 septic in detail, the permitting sequence, and cost ranges town by town.

Want us to check it properly?

A feasibility review looks at your actual septic capacity, setbacks, and buildable area, on site. No obligation.

Schedule a Design Consultation →Typically a 45-minute conversation. No pressure, no obligation.