Gloucester

• Gloucester (a city, not a town) has an adopted ADU ordinance (Section 5.24) in its zoning code, with provisions for both attached and detached ADUs.
• ADUs are allowed by right with a building permit from the Building Inspector -- no special permit or public hearing required.
• Maximum size is 900 sq ft or 50% of principal dwelling, whichever is less, with a maximum of 2 bedrooms.
• Short-term rentals prohibited -- minimum 30-day rental/occupancy term; no boarding or lodging.
• Detached ADUs have tiered height limits: 20 feet (accessory building setbacks) or 24 feet (principal dwelling setbacks).

1. Submit plans: Prior to building permit issuance, submit a site plan, floor plans, and elevations to the Building Inspector showing proposed interior and exterior changes or new building and improvements.

2. Building permit: Apply for a building permit from the Building Inspector. ADUs are allowed by right -- no special permit, public hearing, or discretionary review is required.

3. Comply with codes: Construction must comply with all applicable building codes, fire codes, and health regulations.

4. Parking compliance: Ensure one off-street parking space is available for the ADU, constructed of materials consistent with the existing driveway, with vehicular access to the driveway. No parking between the front building line and front lot line except in the existing driveway.

5. Certificate of occupancy: Obtain before the ADU is occupied.

• Maximum size: 900 square feet of gross floor area or 50% of the gross floor area of the principal dwelling, whichever is less.
• Maximum bedrooms: 2 bedrooms.
• Appearance: The ADU must be designed to maintain the appearance of a single-family dwelling.
• Separate entrance: Required for use by ADU occupant(s).
• Location (attached): The ADU shall be located entirely inside the single-family structure, except where detached ADUs are permitted.
• Detached ADU height:
  • 20 feet if meeting normal accessory building setbacks for the district.
  • 24 feet if meeting normal principal dwelling setbacks for the district.
• Detached ADU setbacks: Must comply with the district's minimum setback requirements for accessory structures.
• Detached ADU relationship: Must maintain a secondary relationship to the principal dwelling.
• One ADU per lot: Maximum of one ADU per lot.

• One off-street parking space required for the ADU, in addition to spaces required for the principal dwelling.
• Parking construction: Must be constructed of materials consistent with the existing driveway and have vehicular access to the driveway.
• Parking location: No parking between the front building line of the principal dwelling and the front lot line, except in the existing driveway.
• Transit exemption: Under state law (760 CMR 71.03), no parking can be required for ADUs within 0.5 miles of a commuter rail station, subway station, ferry terminal, or bus station. Gloucester has a commuter rail station on the Rockport Line; properties within 0.5 miles may qualify for the transit exemption.

• Gloucester is a city, not a town: Despite being referenced as a "town" in some contexts, Gloucester is officially a city. This means its local legislation is an "ordinance" rather than a "bylaw."
• Tiered detached height limits: The 20 ft / 24 ft height structure is unique. Homeowners willing to meet principal dwelling setbacks (which are typically larger) get 4 additional feet of height for detached ADUs.
• 2-bedroom maximum: This is a local limit that may be challenged under state law if it is deemed to unreasonably restrict ADU creation.
• Owner-occupancy preempted: The ordinance's original owner-occupancy requirement (Section 5.24.3.a) is preempted by state law. The text still appears in the codified ordinance with a preemption note.
• No boarding or lodging: The ADU cannot be used for boarding or lodging, and cannot be rented on a weekly or daily basis. The minimum occupancy/rental term is 30 days.
• Parking material requirement: The parking space must match the existing driveway materials -- an unusual local detail worth noting for construction planning.
• Commuter rail proximity: Properties near the Gloucester commuter rail station (Rockport Line) may qualify for the transit parking exemption under state law.

The following is the full text of Gloucester Zoning Ordinance Section 5.24: Accessory Dwelling Units (ADU), as codified on Municode.

SECTION 5.24 - ACCESSORY DWELLING UNITS (ADU)

5.24.1 Purposes and Intent

The purposes of this Section 5.24 are to:

(a) Create the opportunity for accessory dwelling units (ADU) in Gloucester's residential neighborhoods;

(b) Increase diverse housing options while respecting the residential character of Gloucester neighborhoods;

(c) Add rental units to Gloucester's housing;

(d) Encourage a more economic and energy-efficient use of the City's housing supply; and

(e) Provide homeowners with a means of obtaining rental income to defray housing costs.

5.24.2 Procedural Requirements

(a) The Building Inspector shall administer and enforce the provisions of this Section 5.24.

(b) 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.

5.24.3 General Requirements for Accessory Dwelling Units

(a) 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. [PREEMPTED: State law prohibits owner-occupancy requirements]

(b) 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 used for boarding or lodging purposes or used as a rental unit on a weekly or daily basis.

(c) There shall be one off-street parking space for the ADU in addition to off-street parking spaces required for the principal dwelling. The parking space shall be constructed of materials consistent with the existing driveway and shall have vehicular access to the driveway. No parking shall be located between the front building line of the principal dwelling and the front lot line except in the existing driveway. [NOTE: State law limits parking to max 1 space, 0 near transit. Additional parking beyond 1 space is preempted.]

(d) There shall not be more than one ADU on a lot.

(e) The ADU shall be located entirely inside the single-family structure, except in certain cases where detached ADUs are permitted (see 5.24.4).

(f) The ADU shall be designed to maintain the appearance of a single-family dwelling.

(g) The ADU shall have a separate entrance for use by its occupant(s).

(h) The ADU and the principal dwelling shall not be sold or transferred separately.

(i) The ADU shall comply with all applicable building codes, fire codes, and health regulations.

5.24.4 Detached ADUs

(a) For detached ADUs, the building must comply with the district's minimum setback requirements for accessory structures.

(b) Maximum height: 20 feet if meeting normal accessory building setbacks, or 24 feet if meeting normal principal dwelling setbacks.

(c) A detached ADU shall maintain a secondary relationship to the principal dwelling.

5.24.5 Size Requirements

(a) The ADU shall not exceed 900 square feet of gross floor area or 50% of the gross floor area of the principal dwelling, whichever is less.

(b) The ADU shall contain no more than 2 bedrooms.

Gloucester has adopted the Stretch Energy Code. A certified HERS Rater is required for all new construction, including ADUs.

Your ADU must achieve a HERS index of 52 or lower (mixed-fuel) or 55 or lower (all-electric). Going all-electric earns a 3-point offset, making compliance easier. Budget $500–$1,500 for HERS testing.

ERV/HRV mechanical ventilation is now required (bath fans alone don't qualify). If on-site parking is provided, EV-ready wiring is also required.

The following provisions of Gloucester's ADU ordinance are preempted by the state Affordable Homes Act (effective February 2, 2025):

1. Owner-occupancy requirement (Section 5.24.3.a) -- State law (760 CMR 71.03) prohibits requiring the owner to occupy either the ADU or the principal dwelling. The codified ordinance still contains this language, but it is unenforceable for Protected Use ADUs.

2. Parking beyond state limits -- While the ordinance requires 1 space (consistent with state law), the transit exemption from 760 CMR 71.03 also applies: no parking can be required for ADUs within 0.5 miles of a commuter rail station, subway station, ferry terminal, or bus station.

Provisions that likely still apply (reasonable local regulation):

• 30-day minimum rental term (short-term rental restriction is allowed by state law)
• One ADU per lot
• Size limits (900 sq ft / 50% -- consistent with state law)
• Maximum 2 bedrooms (may be challenged)
• Detached ADU height limits (20 ft / 24 ft)
• Setback requirements for accessory structures
• Building permit and inspection requirements
• Design standards (maintaining single-family appearance)
• Parking material and location requirements
• Prohibition on separate sale

• Gloucester Zoning Ordinance Section 5.24 (Municode): https://library.municode.com/ma/gloucester/codes/zoning_ordinance?nodeId=SVSPRE_5.24ACDWUNAD
• City of Gloucester Building Inspector: City Hall, 9 Dale Avenue, Gloucester, MA 01930, Phone: (978) 281-9781
• Massachusetts Affordable Homes Act (H.4977): https://www.mass.gov/info-details/accessory-dwelling-units
• 760 CMR 71.00 (Protected Use ADUs): https://www.mass.gov/regulations/760-CMR-7100-protected-use-accessory-dwelling-units