Topsfield

• Topsfield unanimously adopted a new ADU bylaw at the May 6, 2025 Annual Town Meeting, pending approval by the State Attorney General's office.
• ADUs are permitted by right -- no special permit required -- in accordance with state law.
• Maximum size is 900 sq ft or 50% of principal dwelling, whichever is smaller.
• Previous restrictions (700 sq ft max, one bedroom, one bathroom, special permit, family-member orientation) are preempted by the Affordable Homes Act.
• Topsfield is a small, largely residential community where many properties rely on septic systems (Title 5 compliance is critical).

1. Contact the Building Department: Reach out to the Topsfield Building Department at 8 West Common Street to discuss your project and obtain the current application requirements.
2. Title 5 septic evaluation: If on a septic system, have it evaluated for compliance before applying.
3. Building permit application: Submit a standard building permit application. No special permit or public hearing is required for a single ADU.
4. Construction and inspection: Build in accordance with approved plans and the Massachusetts State Building Code (780 CMR).

Note: As Topsfield was slow to adapt to the state law (the planning coordinator had "not yet met to discuss" the changes as of late 2024), you may encounter administrative delays. Document your rights under state law if you encounter pushback.

• Maximum size: 900 square feet or 50% of the gross floor area of the principal dwelling, whichever is smaller.
• Types: Attached, detached, or internal ADUs are all permitted under state law.
• Separate entrance: Required, either directly from the outside or through a shared entry hall/corridor meeting building code egress requirements.
• Previous restrictions (now preempted): ADU sizes were restricted to one bedroom, one bathroom, and a maximum floor area of 700 square feet, with ZBA discretion to increase the size limit.

• Under state law, a maximum of 1 parking space may be required for an ADU.
• No additional parking may be required for ADUs located within 1/2 mile of a commuter rail station, subway station, ferry terminal, or bus station. Topsfield does not have a commuter rail station, so this exemption has limited applicability.

• Septic systems: Many Topsfield properties rely on septic systems. Title 5 compliance is critical and may be a significant factor in ADU feasibility and cost.
• Historic character: The town center has historic character that may factor into design considerations, though it is unclear whether Topsfield has a formal historic district review requirement for ADUs.
• Agricultural/rural character: Parts of Topsfield have agricultural and rural character. The town is home to the Topsfield Fair (the largest and oldest agricultural fair in the Americas).
• Family-member orientation preempted: The previous zoning language stated that ADU purpose was to "maximize privacy, dignity, and independent living among family members, preserving domestic family bonds as well as the single-family residential character of the neighborhood." This family-member-only orientation is preempted by state law.

Full bylaw text is not available from the sources reviewed. The available information is compiled from news sources and web searches. The following summarizes what is known:

Previous Bylaw Provisions (Pre-State Law)

• ADU sizes restricted to one bedroom and one bathroom
• Floor area no more than 700 square feet
• ZBA had discretion to increase size limit
• Special permit required
• Zoning language oriented toward family-member use: "maximize privacy, dignity, and independent living among family members, preserving domestic family bonds as well as the single-family residential character of the neighborhood"

New Bylaw Provisions (Adopted May 6, 2025)

• ADUs permitted by right (no special permit required)
• Maximum 900 sq ft or 50% of principal dwelling, whichever is smaller
• Owner-occupancy NOT required (per state law)
• Separate entrances permitted
• Aligned with Massachusetts Affordable Homes Act requirements
• Unanimously voted in by residents at Annual Town Meeting
• Pending approval by State Attorney General's office

State Law Requirements (Apply to Topsfield)

• One ADU per single-family lot, allowed by right
• Maximum 900 sq ft or 50% of principal dwelling, whichever is smaller
• No special permit required (standard building permit only)
• No owner-occupancy requirement
• No family-member restrictions
• Maximum 1 parking space (0 if within 0.5 miles of transit)
• Separate entrance required
• Must comply with building codes

Topsfield 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 (Section 8, Chapter 150, Acts of 2024) and 760 CMR 71.00:

• Owner-occupancy requirements: Cannot be imposed on either the principal dwelling or the ADU.
• Special permit requirements: A single ADU in a single-family residential district must be allowed by right.
• Family-member restrictions: The previous zoning language oriented toward family-member-only use is preempted.
• 700 sq ft size limit: Preempted; state law allows up to 900 sq ft.
• One bedroom limit: Likely preempted as unreasonably restrictive.

• The Local News: Topsfield Planners to Start Work on Accessory Dwelling Proposal (October 2024)
• The Local News: Under New State Law, Abutters Have Little Say Over ADUs (September 2025)
• Town of Topsfield - Town Laws
• Town of Topsfield Website