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Can I build an ADU in Rockport, Massachusetts?

Rockport, Essex County · Bylaws checked 2026-10-20 · Reviewed · 14 cited sections

Allowed with a permit

Yes. Rockport's zoning bylaw (posted version updated December 16, 2025) allows one Protected Use ADU per lot by right in every zoning district, attached or detached, with a building permit from the Building Inspector. It can be no larger than 900 square feet or half the main house's floor area, whichever is smaller, and it can never be used as a short-term rental; a six-month minimum lease voted in April 2026 may also apply.

Where allowedOne Protected Use ADU per lot, by right (Y) in all districts [1]
ApprovalBuilding permit from the Building Inspector (attached or detached) [3]
Max size900 sq ft or 1/2 the main house's gross floor area, whichever is smaller [2]
Number of units1 ADU per lot; no more than 2 dwelling units on a single-family lot [5]
SetbacksSame as an accessory structure (Planning Board special permit to vary) [6]
Parking1 space, none if within 1/2 mile of the train station [7]
Short-term rentalProhibited; may not be advertised on STR platforms [8]
Minimum lease (adopted 4/11/2026, AG approval not verified)6 months [10]
Owner-occupancyNot required by the bylaw [1]

What's allowed

Rockport's use table lists "One Protected Use Accessory Dwelling Unit per lot" as allowed by right in every district [1]. A Protected Use ADU is a self-contained unit with its own sleeping, cooking and sanitary facilities and a separate entrance, no larger than half the main house's gross floor area or 900 square feet, whichever is smaller [2]. It can be inside the house or in a detached accessory structure; either way the Building Inspector authorizes it with a building permit [3][4]. Only one ADU is allowed per lot, with no more than two dwelling units on a single-family lot [5]. The bylaw has no owner-occupancy requirement.

Site and design rules

The ADU must meet the setbacks for an accessory structure and other dimensional rules unless the Planning Board grants a special permit [6]. Bedrooms in the house and ADU combined can't exceed the septic system's Title 5 capacity [13]. One parking space is required unless the property is within half a mile of the train station [7]. In a local historic district, the Historical Commission's design standards apply [12]. An attached ADU needs scaled floor plans and elevations showing it won't significantly change the house's appearance.

No short-term rentals

Short-term rentals of a Protected Use ADU are banned, including advertising on rental platforms [8]. Before the Certificate of Occupancy, you register the ADU with the Building Inspector, certify in writing it won't be rented short-term [9], and record a notice at the Essex South District Registry of Deeds.

2026 change and numbering

The April 11, 2026 Annual Town Meeting passed Article M, adding "The minimum length of a lease for a Protected Use ADU shall be six months" [10][11]. It was adopted by Town Meeting, but we could not verify Attorney General approval, and it is not yet in the town's posted zoning PDF (updated December 16, 2025). That PDF still uses the old numbering (Section V.C); the September 2025 recodification renumbered it as Zoning Chapter 400, §400-16. The bylaw's own ADU definition, which follows state law, lets towns restrict short-term rentals (as defined in the state rental-tax law, M.G.L. c. 64G) but says no town may unreasonably restrict renting an ADU that is not a short-term rental [14]. A six-month minimum would also bar rentals longer than a short-term rental, so state law may override it.

See how Rockport compares with 8+ other Massachusetts towns on accessory dwelling units (adus) →

Next steps

  1. Confirm the ADU's size (no more than 900 sq ft or half the main house's floor area) and that it meets accessory-structure setbacks and your septic capacity.
  2. Submit a building permit application with scaled floor plans and elevations to Inspectional Services (978-546-9218), 34 Broadway, or through the town's online permit portal.
  3. If you're in one of the four local historic districts, apply to the Historical Commission for a certificate first.
  4. Before the Certificate of Occupancy, register the ADU with the Building Inspector, sign the no-short-term-rental certification, and record the Building Inspector's notice at the Essex South District Registry of Deeds.
  5. If you plan to rent the ADU, ask the Building Inspector whether the six-month minimum lease (2026 Article M) is in effect.

Common questions

Can I build an ADU in Rockport, Massachusetts?
Yes. Rockport's zoning bylaw (posted version updated December 16, 2025) allows one Protected Use ADU per lot by right in every zoning district, attached or detached, with a building permit from the Building Inspector. The bylaw has no owner-occupancy requirement.
How big can an ADU be in Rockport, MA?
No larger than 900 square feet or half the main house's gross floor area, whichever is smaller. Only one ADU is allowed per lot, it must meet accessory-structure setbacks unless the Planning Board grants a special permit, and bedrooms in the house and ADU combined can't exceed the septic system's Title 5 capacity.
Can I rent my ADU on Airbnb in Rockport, Massachusetts?
No. Short-term rentals of a Protected Use ADU are banned, including advertising on rental platforms. Before the Certificate of Occupancy you register the ADU with the Building Inspector, certify in writing it won't be rented short-term, and record a notice at the Essex South District Registry of Deeds.
Is there a minimum lease for an ADU in Rockport, MA?
Possibly. The April 11, 2026 Town Meeting passed Article M setting a six-month minimum lease for Protected Use ADUs, but Attorney General approval wasn't verified and it isn't in the posted zoning bylaw. State law bars unreasonable limits on renting an ADU that isn't a short-term rental, so state law may override it. Ask the Building Inspector whether it's in effect.
Do I need parking for an ADU in Rockport, Massachusetts?
One parking space is required for the ADU unless the property is within half a mile of the train station, in which case none is required.

Massachusetts' statewide ADU law

Since February 2, 2025, the Affordable Homes Act (St. 2024, c. 150, §8) has protected one accessory dwelling unit (ADU) per lot in any zoning district that allows single-family homes (M.G.L. c. 40A, §3). Your town cannot ban it, require a special permit or other discretionary approval, or "unreasonably restrict" building or renting it.

What counts as a protected ADU:

  • A self-contained unit with its own sleeping, cooking and bathroom facilities, on the same lot as the main home.
  • No larger than 900 sq ft or half the main home's floor area, whichever is smaller.
  • It can be attached or detached, and it needs a separate entrance that meets the building code.

What towns cannot require:

  • That the owner live in the main home or the ADU.
  • More than 1 extra parking space, or any extra space if the lot is within 0.5 miles of a subway, commuter rail, ferry or bus station.
  • A minimum lot size, caps on the number of ADUs, or limits on who may live there (age, income, relationship).

What towns can still do: use reasonable site plan review, setback, height and bulk rules, require Title 5 septic compliance, and restrict or ban short-term rentals of ADUs. A second ADU on the same lot needs a special permit. State regulations at 760 CMR 71.00 (in effect since January 31, 2025) explain which rules count as unreasonable.

State sources: M.G.L. c. 40A, §3 (protected ADU paragraph) · M.G.L. c. 40A, §1A (ADU definition) · EOHLC, Accessory Dwelling Units (law, FAQ, 2026 draft regulations) · 760 CMR 71.00, Protected Use Accessory Dwelling Units

What the bylaw says

Exact text from Rockport's published bylaws. Section numbers are as printed in the source.

  1. Section V.B Table of Permitted Uses, I. Residential, line E, Town of Rockport Zoning By-Law (2025 edition, 'Updated: December 16, 2025'; linked as 'Updated 12-4-2025'), p. 22
    E. One Protected Use Accessory Dwelling Unit per Y Y Y Y Y Y lot.
  2. Section V.C.1 Definitions, Protected Use Accessory Dwelling Unit (ADU), Town of Rockport Zoning By-Law (2025 edition, 'Updated: December 16, 2025'; linked as 'Updated 12-4-2025'), p. 26
    (b) is not larger in Gross Floor Area than ½ the Gross Floor Area of the Principal Dwelling or 900 square feet, whichever is smaller; and
  3. Section V.C.2(1)(b), Town of Rockport Zoning By-Law (2025 edition, 'Updated: December 16, 2025'; linked as 'Updated 12-4-2025'), p. 28
    (b) Protected Use ADUs within an existing or new single-family, duplex or multi- family dwelling may be authorized by the Building Inspector with the issuance of a building permit when the conditions and requirements have been met.
  4. Section V.C.2(1)(c), Town of Rockport Zoning By-Law (2025 edition, 'Updated: December 16, 2025'; linked as 'Updated 12-4-2025'), p. 28
    (c) Protected Use ADUs in an accessory structure detached from an existing or new single-family, duplex or multi-family dwelling may be authorized by the Building Inspector with the issuance of a building permit when the conditions and requirements have been met
  5. Section V.C.2(2)(b), Town of Rockport Zoning By-Law (2025 edition, 'Updated: December 16, 2025'; linked as 'Updated 12-4-2025'), p. 28
    (b.) No more than one Protected Use ADU may be created on a lot. There shall be, and no more than two dwelling units on a single-family lot.
  6. Section V.C.2(2)(e), Town of Rockport Zoning By-Law (2025 edition, 'Updated: December 16, 2025'; linked as 'Updated 12-4-2025'), p. 29
    (e) An attached or detached Protected Use ADU Unit shall meet the setback requirements or of an accessory structure, as well as other applicable dimensional controls, except by Special Permit from the Planning Board.
  7. Section V.C.2(2)(h), Town of Rockport Zoning By-Law (2025 edition, 'Updated: December 16, 2025'; linked as 'Updated 12-4-2025'), p. 29
    (h) One parking space shall be required for the Protected Use ADU shall be required where the property is more than one half mile from the train station, with no parking requirement for a property being within one half mile of the train station.
  8. Section V.C.2(2)(i)1, Town of Rockport Zoning By-Law (2025 edition, 'Updated: December 16, 2025'; linked as 'Updated 12-4-2025'), p. 29
    1. Short-term rentals are prohibited in Protected Use ADUs and may not be advertised or promoted on any internet platforms typically associated with short term rentals;
  9. Section V.C.2(2)(i)2, Town of Rockport Zoning By-Law (2025 edition, 'Updated: December 16, 2025'; linked as 'Updated 12-4-2025'), p. 29
    2. Before a Certificate of Occupancy is issued the property owner of any Protected Use ADU shall register such property with the Building Inspector and provide written certification attesting that the Protected ADU shall not be used for short-term rentals;
  10. April 11, 2026 ATM Warrant, Article M (amending Section 400-16(i)[1]), Annual Town Meeting Warrant, April 11, 2026 (True Copy) - Art. M amending Zoning §400-16 Protected Use ADUs, p. 9
    The minimum length of a lease for a Protected Use ADU shall be six months.
  11. Recap, April 11, 2026 Annual Town Meeting, Recap of Articles Pass/Fail - Annual Town Meeting, April 11, 2026, p. 1
    Passed – voice Article M (8): ADU by-law length of lease 6mo minimum
  12. Section V.C.2(2)(g), Town of Rockport Zoning By-Law (2025 edition, 'Updated: December 16, 2025'; linked as 'Updated 12-4-2025'), p. 29
    (g) Attached or detached Protected Use ADUs to be located within an historic district within the Town of Rockport shall be subject to the local Historical Commission design standards for the district for a single-family residential dwelling. Permissions shall not be unreasonably withheld.
  13. Section V.C.2(2)(c), Town of Rockport Zoning By-Law (2025 edition, 'Updated: December 16, 2025'; linked as 'Updated 12-4-2025'), p. 28
    (c)The total number of bedrooms in the primary dwelling and the Protected Use ADU combined may not exceed the capacity of the permitted septic system, per Title V requirements.
  14. Section V.C.1 Definitions, Protected Use Accessory Dwelling Unit (ADU), clause (c), Town of Rockport Zoning By-Law (2025 edition, 'Updated: December 16, 2025'; linked as 'Updated 12-4-2025'), p. 26
    (c) is subject to such additional restrictions as may be imposed by a municipality including, but not limited to, additional size restrictions, and restrictions or prohibitions on Short-term Rental as defined in M.G.L. c. 64G, § 1; provided, however, that no Municipality shall unreasonably restrict the creation or rental of an ADU that is not a Short-term Rental.
This page summarizes Rockport's posted bylaws as of 2026-10-20. Bylaws are amended, and individual lots can have overlays, subdivision covenants, or HOA rules that are stricter. Confirm with Inspectional Services Department (Inspector of Buildings Paul Orlando, also zoning enforcement), Town Hall, 34 Broadway (office at 26 Broadway), Rockport MA 01966 (978-546-9218) before you build. Spot an error?