Manchester-by-the-Sea

• Manchester-by-the-Sea has adopted a two-tier ADU system through Town Meeting warrant articles: Standard ADUs (up to 900 sq ft) are by right under Article 8; Large ADUs (901-1,200 sq ft) require a Special Permit under Article 9.
• Standard ADUs follow state law: maximum 900 sq ft or 50% of the principal dwelling, whichever is smaller, approved by right with no special permit needed.
• Large ADUs allow up to 1,200 sq ft or 50% of the principal dwelling (whichever is smaller) but require a Special Permit with additional requirements.
• Article 10 prohibits short-term rental of any ADU (both standard and large).
• The FAQ source (April 15, 2025) was prepared by Planning Board members to help residents understand warrant Articles 8, 9, and 10.

Standard ADU (up to 900 sq ft)

1. Prepare application: Standard building permit application with plans and documentation.
2. Submit to Building Department: No special permit or public hearing required.
3. Demonstrate compliance: Must comply with Article 8 provisions and all applicable building codes.
4. Receive building permit: Approved by right if requirements are met.

Large ADU (901-1,200 sq ft)

1. Prepare application: Building permit application plus Special Permit application with additional documentation per Article 9.
2. Submit Special Permit application: May involve Planning Board or ZBA review.
3. Public hearing: Special Permit process typically requires a public hearing.
4. Additional requirements: Article 9 imposes additional requirements beyond those for standard ADUs.
5. Receive Special Permit and building permit: Subject to board approval and conditions.

Standard ADU (Article 8)

• Maximum size: 900 sq ft or half the gross floor area of the principal dwelling, whichever is smaller.
• Separate entrance: Required, either directly from the outside or through a shared entry hall/corridor meeting building code egress requirements.
• Self-contained: Must include sleeping, cooking, and sanitary facilities.
• Types: May be enclosed in a home (internal), attached to a home, or contained within a detached structure on the same lot.
• Article 8 "puts as many guardrails on these smaller ADUs as are allowed by law."

Large ADU (Article 9)

• Maximum size: Up to 1,200 sq ft or half the gross floor area of the principal dwelling, whichever is smaller.
• Additional requirements: Article 9 contains additional standards beyond those for standard ADUs. Full text of Article 9 was not available in the source document.

• Parking: Per state law, a maximum of 1 off-street parking space may be required for an ADU located more than 0.5 miles from transit. No additional parking may be required for ADUs within 0.5 miles of a commuter rail station, subway station, ferry terminal, or bus station.
• Specific local parking provisions were not detailed in the available FAQ source.

• Two-tier system: Manchester-by-the-Sea is notable for creating a "Large ADU" category (901-1,200 sq ft) beyond the state-mandated standard ADU. This is a creative approach that maximizes local flexibility while complying with state law.
• Short-term rental prohibition: Article 10 explicitly prohibits short-term rental of any ADU, whether standard or large. This is one of the strongest STR prohibitions available under state law.
• Limited source data: The primary source is a 5-page FAQ document (April 15, 2025) prepared by Planning Board members. Only the first page was fully transcribed. The full bylaw text for Articles 8, 9, and 10 should be obtained from the Town Clerk or the town website for complete details.
• Verify dimensional requirements: The FAQ advises residents to verify current dimensional requirements for their specific zoning district.

Source: Accessory Dwelling Unit -- Frequently Asked Questions (April 15, 2025)

The Warrant for Town Meeting includes three articles covering Accessory Dwelling Units "ADUs". Members of the Planning Board prepared this guide to help residents understand Warrant Articles 8, 9 and 10.

In summary:

ARTICLE 8 fixes our Zoning By-Law so that Manchester's restrictions on ADUs sized 900 square feet or smaller conform to current State Law and puts as many guardrails on these smaller ADUs as are allowed by law. Article 8 also removes our existing ADU rules.

ARTICLE 9 adds a new Zoning By-Law that contains rules for ADUs that are between 901 square feet and 1200 square feet. These Larger ADUs have additional requirements including a special permit requirement.

ARTICLE 10 prohibits the short-term rental of any ADU.

Definitions

ADU: An ADU is an "Accessory Dwelling Unit." The most common examples of ADUs are: a carriage house, a tiny house, a basement or attic apartment, and a garage apartment. ADUs are either enclosed in a home, attached to a home, or contained within a detached structure that is on the same lot as the home.

The State of Massachusetts defines an ADU as: A self-contained housing unit, inclusive of sleeping, cooking and sanitary facilities on the same Lot as a Principal Dwelling, ... that:

• Maintains a separate entrance, either directly from the outside or through an entry hall or corridor shared with the Principal Dwelling sufficient to meet the requirements of the state building code for safe egress; and
• Is not larger in gross floor area than 1/2 the gross area of the principal dwelling or 900 square feet, whichever is smaller.

PRINCIPAL DWELLING: The main house on a lot.

Two-Tier ADU System

Standard ADU (up to 900 sq ft):

• By right (no special permit needed)
• 900 sq ft or half the size of the Primary Dwelling, whichever is smaller
• Governed by state law and Article 8

Large ADU (901 to 1,200 sq ft):

• Requires a Special Permit
• Up to 1,200 sq ft or half the size of the Primary Dwelling, whichever is smaller
• Governed by Article 9
• Additional requirements apply

Short-Term Rentals:

• Article 10 prohibits the short-term rental of ANY ADU (standard or large)

Note: This is a 5-page PDF document. Full text could not be programmatically extracted from the PDF viewer. The above content was transcribed from page 1 of the source document. Visit the source URL to access the full document.

Manchester-by-the-Sea 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 local provisions are preempted by the Massachusetts Affordable Homes Act (Chapter 150 of the Acts of 2024) and 760 CMR 71.00:

• Owner occupancy: State law prohibits municipalities from imposing owner-occupancy requirements for either the ADU or the principal dwelling.
• Previous local ADU rules: Article 8 explicitly removes Manchester's existing ADU rules and replaces them with provisions that conform to state law.
• Special permit for standard ADUs: State law mandates by-right approval for ADUs up to 900 sq ft. Manchester complies by making standard ADUs by-right under Article 8.
• Large ADU special permit: The Special Permit requirement for Large ADUs (901-1,200 sq ft) is permissible because it applies only to units exceeding the state-mandated 900 sq ft threshold. State law only requires by-right approval for ADUs up to 900 sq ft.

• Manchester-by-the-Sea ADU FAQs (April 15, 2025): https://manchester.ma.us/DocumentCenter/View/8616/ADU-FAQs-2025
• Town of Manchester-by-the-Sea Bylaws and Regulations: https://www.manchester.ma.us/685/Bylaws-and-Regulations
• Town of Manchester-by-the-Sea website: https://www.manchester.ma.us
• Massachusetts Affordable Homes Act (H.4977 / St. 2024, c. 150)
• 760 CMR 71.00 (Protected Use Accessory Dwelling Units)