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Can I build an ADU in Gloucester, Massachusetts?

Gloucester, Essex County · Bylaws checked 2026-10-15 · Reviewed · 14 cited sections

Allowed with a permit

Yes. Gloucester's zoning (Sec. 5.24, adopted 2021) allows one ADU per lot with a single-family home in the residential districts (R-80 through R-5), up to 900 sq ft or 50% of the home's habitable floor area, whichever is less, with a building permit from the Building Inspector. The ordinance still requires the owner to live on site and keeps attached ADUs inside the existing house, but Massachusetts' ADU law (since Feb. 2, 2025) may override those limits for one ADU.

Number per lot1 [5]
Max size (attached)Lesser of 50% of habitable floor area or 900 sq ft [6]
Max size (detached)Lesser of 900 sq ft or 50% of the main home's habitable space [7]
Detached ADU max height20 ft at accessory setbacks; 24 ft at principal-dwelling setbacks [11]
Extra parking1 off-street space (state law may limit) [4]
Minimum rental term30 days (no weekly or daily rental) [9]
Owner-occupancy (ordinance)Required; state law may override [3]
ApprovalBuilding permit; site plan, floor plans, elevations to Building Inspector [2]
Districts (use table)Allowed in R-80, R-40, RC-40, R-30, R-20, R-10, R-5; not listed in business/industrial districts [13]

What counts as an ADU

Gloucester defines an ADU as a separate dwelling unit with its own living, cooking, sleeping and sanitation facilities, either inside a detached single-family home ("attached") or in a separate building on the same lot ("detached"), held in the same ownership as the main home [1]. The accessory-use table (Sec. 2.3.7, line 20) marks ADUs "Y" (allowed) in all seven residential districts (R-80, R-40, RC-40, R-30, R-20, R-10, R-5) and "N" in the business and industrial districts, even though Sec. 5.24.4 says an attached ADU is allowed "in any district" [13]. An attached ADU must be in an owner-occupied, existing single-family home and located entirely inside it.

Size and design

Only one ADU is allowed per lot, and it can't be split off as a condo [5]. An attached ADU is capped at 50% of the home's habitable floor area or 900 sq ft, whichever is less, and must keep the look of a single-family home [6]. A detached ADU has the same cap [7]. A new detached building must meet the accessory-structure setbacks and can be 20 ft tall, or 24 ft if it meets principal-dwelling setbacks [8][11][12].

Parking and rentals

The ordinance requires one extra off-street space for the ADU, with no new parking between the house front and the street except in the existing driveway [4]. If either unit is rented, the minimum term is 30 days, and neither may be rented weekly or daily [9].

Approval

The Building Inspector runs the process. Before a building permit is issued, you submit a site plan, floor plans and elevations [2]. An ADU that doesn't meet these standards can get a special permit from the Zoning Board of Appeals [10][14].

State law

Section 5.24 was adopted in 2021, before Massachusetts' Protected Use ADU law took effect on February 2, 2025. The ordinance's rule that the owner must live in one of the units [3] conflicts with that law, and state law may override it for one by-right ADU. Parts of the 5.24.4 limits (attached ADUs only inside an existing owner-occupied house) and the special-permit route may also be overridden for a protected ADU. State law protects one ADU in any district that allows single-family homes, which in Gloucester includes the CCD, VB and NB districts where the use table says no. The state also caps extra parking at one space, and bars any parking requirement within half a mile of a commuter rail station or other transit stop; Gloucester's ordinance has no such exemption. The 30-day rental minimum is the kind of short-term-rental limit state law still lets cities impose.

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

Next steps

  1. Confirm your zoning district on the city's zoning map; ADUs are listed in the R-80 through R-5 residential districts.
  2. Measure the main home's habitable floor area (not counting garage, unfinished attic or basement, porches or decks) to find your 900 sq ft / 50% cap.
  3. Prepare a site plan, floor plans and elevations and apply for a building permit with Inspectional Services (Building Inspector), 3 Pond Road, 978-325-5210.
  4. Ask Inspectional Services how the city applies the owner-occupancy and parking rules after the 2025 state ADU law before you design.
  5. If your ADU doesn't meet the Sec. 5.24 standards, apply to the Zoning Board of Appeals for a special permit.

Common questions

Are ADUs allowed in Gloucester, Massachusetts?
Yes. Gloucester's Sec. 5.24 allows one accessory dwelling unit per lot with a single-family home in the residential districts R-80 through R-5, with a building permit from the Building Inspector. The ordinance's use table marks ADUs not allowed in business and industrial districts, but Massachusetts' 2025 ADU law protects one ADU in any district that allows single-family homes.
How big can an ADU be in Gloucester, Massachusetts?
An attached or detached ADU is capped at 900 sq ft or 50% of the main home's habitable floor area, whichever is less. A new detached ADU building can be 20 ft tall at accessory-structure setbacks, or 24 ft if it meets principal-dwelling setbacks.
Does the owner have to live on site to have an ADU in Gloucester, Massachusetts?
It depends. Gloucester's ordinance, adopted in 2021, requires the owner to live in one of the units, but that conflicts with the Massachusetts Protected Use ADU law in effect since February 2, 2025, which may override it for one by-right ADU. Ask Inspectional Services how the city applies the owner-occupancy and parking rules before you design.
Can I rent out an ADU as an Airbnb in Gloucester, Massachusetts?
No, not short-term. If either the ADU or the main home is rented, the minimum term is 30 days, and neither may be rented weekly or daily. State ADU law still lets cities impose this kind of short-term-rental limit, and the city's short-term rental ordinance also excludes auxiliary dwelling units.
How do I get an ADU permit in Gloucester, Massachusetts?
Submit a site plan, floor plans and elevations to the Building Inspector at Inspectional Services and get a building permit. The ordinance also requires one extra off-street parking space, though state law may limit that. An ADU that doesn't meet the Sec. 5.24 standards can seek a special permit from the Zoning Board of Appeals.

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 Gloucester's published bylaws. Section numbers are as printed in the source.

  1. Section VI - Definitions, Accessory Dwelling Unit (ADU), Zoning Ordinance Section VI - Definitions
    A separate dwelling unit with provisions for living, eating, cooking, sleeping, and sanitation located inside a Detached Single-Family Dwelling (an "Attached ADU") or in a detached building located on the same lot as a Detached Single-Family Dwelling (a "detached ADU"), as an accessory and subordinate use to the principal dwelling and held in the same ownership as the principal dwelling.
  2. Sec. 5.24.2(b), Zoning Ordinance Section V - Special Regulations (5.3 Home Occupations, 5.5 Floodplain Overlay, 5.24 ADUs, etc.)
    Prior to issuance of a building permit for an ADU, the applicant shall submit a site plan, floor plans, and elevations to the Building Inspector showing the proposed interior and exterior changes to existing buildings or new building and improvements on a lot associated with a proposed ADU.
  3. Sec. 5.24.3(a), Zoning Ordinance Section V - Special Regulations (5.3 Home Occupations, 5.5 Floodplain Overlay, 5.24 ADUs, etc.)
    The owner(s) of the single-family dwelling in which the accessory dwelling unit is created must continue to occupy one of the units as their residence, except for bona fide temporary absences.
  4. Sec. 5.24.3(c), Zoning Ordinance Section V - Special Regulations (5.3 Home Occupations, 5.5 Floodplain Overlay, 5.24 ADUs, etc.)
    There shall be one off-street parking space for the ADU in addition to off- street parking spaces required for the principal dwelling.
  5. Sec. 5.24.3(e), Zoning Ordinance Section V - Special Regulations (5.3 Home Occupations, 5.5 Floodplain Overlay, 5.24 ADUs, etc.)
    There shall not be more than one ADU on a lot. ADUs shall not be eligible for zoning dimensional variances proposing to increase the allowable number of ADUs on a lot. No ADU shall be separated from the principal dwelling through a condominium or cooperative conversion process or be held in separate ownership from the principal dwelling unit on the lot.
  6. Sec. 5.24.4(b)1, Zoning Ordinance Section V - Special Regulations (5.3 Home Occupations, 5.5 Floodplain Overlay, 5.24 ADUs, etc.)
    The accessory dwelling unit shall be a maximum of 50 percent of the habitable floor area of the single-family dwelling, or 900 square feet, whichever is less.
  7. Sec. 5.24.5(a), Zoning Ordinance Section V - Special Regulations (5.3 Home Occupations, 5.5 Floodplain Overlay, 5.24 ADUs, etc.)
    A Detached ADU shall be maximum of 900 square feet or 50 percent of the total habitable space of the principal dwelling, whichever is less.
  8. Sec. 5.24.5(c), Zoning Ordinance Section V - Special Regulations (5.3 Home Occupations, 5.5 Floodplain Overlay, 5.24 ADUs, etc.)
    For new construction of a Detached ADU, the building shall comply with the district's minimum setback requirements for accessory structures.
  9. Sec. 5.24.3(b), Zoning Ordinance Section V - Special Regulations (5.3 Home Occupations, 5.5 Floodplain Overlay, 5.24 ADUs, etc.)
    Where the ADU or the principal dwelling is occupied as a rental unit, the minimum occupancy or rental term shall be 30 days. No ADU shall be use for boarding or lodging purposes or used as a rental unit on a weekly or daily basis.
  10. Sec. 5.24.6(a), Zoning Ordinance Section V - Special Regulations (5.3 Home Occupations, 5.5 Floodplain Overlay, 5.24 ADUs, etc.)
    The Zoning Board of Appeals may grant a special permit for an ADU that does not meet the above requirements provided the Board finds that the proposed ADU meets the purposes of this Section
  11. Sec. 5.24.5(c)i-ii, Zoning Ordinance Section V - Special Regulations (5.3 Home Occupations, 5.5 Floodplain Overlay, 5.24 ADUs, etc.)
    20 feet if the structure meets the normal accessory building setbacks, or
  12. Sec. 5.24.5(c)i-ii, Zoning Ordinance Section V - Special Regulations (5.3 Home Occupations, 5.5 Floodplain Overlay, 5.24 ADUs, etc.)
    24 feet if the structure meets the normal principal dwelling setbacks.
  13. Sec. 5.24.4, Zoning Ordinance Section V - Special Regulations (5.3 Home Occupations, 5.5 Floodplain Overlay, 5.24 ADUs, etc.)
    An Attached ADU that conforms to all of the following requirements shall be permitted as an accessory use in any district in an owner-occupied, lawfully existing detached single-family dwelling.
  14. Sec. 2.3.7, footnote (5), Zoning Ordinance Section II - Use Regulations (Municode, Supp. No. 8, codified through Ord. No. 2025-233, adopted Sept 12, 2025)
    Accessory dwelling units that do not meet the dimensional standards of Section 5.24 may be allowed by the issuance of a special permit from the Zoning Board of Appeals.
This page summarizes Gloucester's posted bylaws as of 2026-10-15. Bylaws are amended, and individual lots can have overlays, subdivision covenants, or HOA rules that are stricter. Confirm with Inspectional Services (Building Commissioner), 3 Pond Road (978-325-5210) before you build. Spot an error?