Accessory Dwelling Units
ADU Permitting in Massachusetts
Massachusetts changed the rules — ADUs are now allowed by-right in single-family zones statewide. We help Greater Boston homeowners turn that into a permitted, buildable unit.
Under Massachusetts' Affordable Homes Act, accessory dwelling units of up to 900 square feet are allowed by-rightin single-family zoning districts statewide as of February 2, 2025 — no special permit required for a conforming unit. Local dimensional rules still apply, so the details of your lot decide what's actually buildable.
What is an ADU?
An accessory dwelling unit is a smaller, independent home on the same lot as a single-family house — a backyard cottage, a converted basement or attic, or an addition with its own kitchen, bath, and entrance. ADUs add housing gently, create rental income, and let families age in place or house relatives nearby.
What we handle for you
- Zoning and feasibility read confirming whether your ADU is by-right or needs relief
- Test-fit sizing against setbacks, height, lot coverage, and the 900 sq ft cap
- Building and zoning application preparation and document assembly
- Coordination of your architect, surveyor, and other consultants
- Planning Board / ZBA preparation if any discretionary review is triggered
How ADU permitting works
Every ADU engagement follows the same path — so you always know the next step and what it takes to get to approval.
Confirm your lot qualifies
We review your parcel against the local zoning bylaw and Massachusetts' ADU law to confirm whether an accessory dwelling unit is allowed by-right or needs relief.
Test-fit the unit
We size the ADU against dimensional rules — setbacks, lot coverage, height, and the 900 sq ft cap — so the design works before you spend on full plans.
Assemble the application
We prepare the building and zoning submission, coordinate your architect and surveyor, and compile the narrative and plans the municipality requires.
File and follow through
We file with the town, respond to comments, and — if any discretionary review is triggered — prepare you for the Planning Board or ZBA hearing.
ADU help in your city or town
Local rules vary across Greater Boston. We work throughout the region — here are a few of the communities we serve:
ADU FAQ
ADU Questions, Answered
Are ADUs now allowed by-right in Massachusetts?
Yes. Under Massachusetts' Affordable Homes Act, accessory dwelling units of up to 900 square feet are allowed by-right in single-family zoning districts statewide, effective February 2, 2025 — meaning no special permit or discretionary review for a conforming unit. Local dimensional standards (setbacks, height, lot coverage) still apply, which is where most projects need a careful read.
How big can my ADU be?
The state standard allows an ADU that is the lesser of 900 square feet or half the gross floor area of the principal dwelling. Some communities are more permissive. We confirm the exact limit for your address before you design.
Do I need extra parking for an ADU?
In many cases communities cannot require more than one additional parking space for a by-right ADU, and that requirement is waived near transit. The specifics depend on your municipality — we verify it as part of the feasibility read.
Can the ADU be a separate building in my backyard?
Often yes — detached ADUs are permitted in many Greater Boston communities, subject to setbacks and lot coverage. Whether detached, attached, or interior (e.g. a basement conversion) is feasible comes down to your specific lot.
How long does ADU permitting take?
A clean by-right ADU can move quickly once plans are complete, since no discretionary hearing is required. Timelines stretch when relief is needed or when plans require revision — our job is to get you onto the by-right path wherever possible.
What does Pavli charge to help with an ADU?
Engagements typically start with a fixed-fee feasibility read so you know what's possible before committing further. Full permitting support is scoped to your project. The initial consultation is free — reach out and we'll outline next steps.