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ADU Design & Build on the North Shore

An attached or interior ADU adds a complete small home, with its own kitchen, bath and entrance, to the house you already have. A design-build team handles drawings, permits and construction under one contract. We connect you with independent local pros who can quote it.

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Architectural plans for an in-law apartment addition on a table

Why the 2025 ADU law matters

The rules changed statewide. Here is what that means for a North Shore lot.

Allowed by right

Since February 2, 2025, one ADU per lot is allowed by right in single-family zoning districts. Towns cannot require a special permit for a protected ADU.(Mass.gov: Accessory dwelling units (ADUs))

No owner-occupancy or family requirement

Towns cannot require the owner to live on the property or require that the ADU be occupied by family.(Mass.gov: Accessory dwelling units (ADUs), 760 CMR 71.00: Protected use accessory dwelling units)

Size and entrance rules

A protected ADU can be no larger than half the main house's gross floor area or 900 square feet, whichever is smaller, and must have its own entrance.(760 CMR 71.00: Protected use accessory dwelling units)

Local rules still apply

Towns may still use site plan review, setbacks and dimensional rules, short-term rental limits, and Title 5 septic requirements.(Mass.gov: Accessory dwelling units (ADUs), MassDEP: Guidance on Title 5 compliance for accessory dwelling units (PDF))

From idea to move-in

  1. Feasibility. The designer reviews your lot, zoning, setbacks, utilities and, if you are on septic, Title 5 capacity.
  2. Design. Plans are drawn to stay within the state size cap and to provide a separate entrance that meets building code egress rules.
  3. Permits. The team files for the building permit and any local site plan review, plus electrical, plumbing and gas permits.
  4. Build and inspect. Construction, inspections, and a certificate of occupancy before anyone moves in.

Is this a good fit?

  • You want a parent, adult child or caregiver close by but with their own space
  • You have an underused wing, attic or part of the house with its own potential entrance
  • You want rental income from your property
  • You would rather add on than move
  • You want one team responsible for design and construction

Further reading: Mass.gov: Accessory dwelling units (ADUs) · 760 CMR 71.00: Protected use accessory dwelling units · MassDEP: Guidance on Title 5 compliance for accessory dwelling units (PDF) · Mass.gov: Check a home improvement contractor registration · Mass.gov: When is a construction supervisor license required?

Every job is different. The pro you speak with will explain their own approach and pricing. North Shore ADU Pros does not perform, supervise, or guarantee any work.

ADU questions

How big can an ADU be in Massachusetts?

Under state rules a protected ADU can be no larger than half the gross floor area of the main house or 900 square feet, whichever is smaller.

Does the ADU need its own entrance?

Yes. Under the state rules a protected ADU must have a separate entrance, either directly from outside or through an entry that meets building code egress requirements.

Do you build ADUs?

No. North Shore ADU Pros is a free service that connects you with independent local designers and builders, who quote and do the work themselves.

How many ADUs have been approved in Massachusetts?

The state's Executive Office of Housing and Livable Communities reported 2,084 ADUs approved and 2,824 applications statewide from 2025 through the first half of 2026.

How much parking can a town require?

No more than one space for a protected ADU, and none if the lot is within half a mile of a commuter rail, subway, ferry or bus station.

Other ADU types

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