Can you build an apartment on your property?

Since February 2025, Massachusetts law requires every city and town to allow one accessory dwelling unit by right on a single-family lot. Seven questions and we'll tell you what the state guarantees you — including the square footage you're actually allowed, which is usually not the 900 you've read about.

What town are you in?

Only used to word the answer. Nothing is looked up and nothing is stored.

What kind of home is it?

The state protection applies to lots in districts that allow single-family homes — which is most residential zoning in Massachusetts.

Single-family house Two-family Condo or townhouse Something else

How many separate homes are on the lot right now?

Counting the main house. If there's already an apartment with its own kitchen and entrance, count it.

Just the one Two More than two

Roughly how big is your house?

A rough number is fine — your listing, tax bill, or assessor's card will have one. This is the number that sets your size limit, so leaving it blank means we can't give you one. Don't count the garage.

Where would the apartment go?

Inside the house — basement, attic, part of the floor plan In the attached garage An addition onto the house In the detached garage or barn Above the detached garage A new building in the yard

Would it have its own kitchen?

This is the line between an apartment and a bedroom suite, and the two follow completely different rules.

Yes — a real kitchen No — just a bedroom and bath

Town sewer, or a septic tank?

If you've never had a tank pumped, you're almost certainly on town sewer. This is the item that most often decides an ADU project — but a screen can't resolve it.

Town sewer Septic tank Not sure

Nothing is sent anywhere. The answer is worked out in your browser.

Leave this empty

Ask about a feasibility report

Your answers above come with it, so there's nothing to repeat. We'll come back to you with what the report would cover for your address and what it costs.

Your name

Phone — optional

Property address

Anything we should know? — optional

No payment now — this is a question, not an order.

We use this to answer you about this property, and nothing else. No mailing list, no third parties, no tracking on this page.

What this is: a plain-English reading of Massachusetts state law — 760 CMR 71.00, effective January 31, 2025 — applied to what you told us. It is the same for every lot in your town, because the state floor is the same everywhere. What it is not: legal advice, a zoning determination, or a reading of your town's own bylaw. Your town may be more generous than the state floor; it cannot be stricter. Nothing here is specific to your address.

Bircch · canibuildthis.com · buildability & permitting, Massachusetts