Lynn

• Lynn allows ADUs under Massachusetts state law defaults -- the city does not have a dedicated local ADU ordinance or specific ADU bylaw section.
• One ADU per single-family lot, allowed by right with a standard building permit.
• Maximum 900 sq ft or 50% of the principal dwelling, whichever is smaller.
• No owner-occupancy, no family-member restrictions, no special permit required.
• Groundwater Protection District may affect ADU development in certain areas of the city -- check if your property falls within this district before proceeding.

1. Submit a written request for Zoning Determination via lynnisdportal.com to confirm property eligibility and zoning district.
2. Confirm the property is in a single-family residential zoning district (Lynn has 15 zoning districts).
3. Apply for a building permit through the Inspectional Services Department at City Hall, Room 405.
4. Comply with all building codes (780 CMR State Building Code) and safety standards.
5. If the property is in the Groundwater Protection District, verify any additional requirements related to bedrooms and development intensity.
6. Comply with Title 5 (310 CMR 15.000) for septic systems where applicable.
7. Pass all required inspections.
8. Obtain Certificate of Occupancy before use.

• Maximum size: 900 sq ft or 50% of the principal dwelling gross floor area, whichever is smaller (state default)
• Separate entrance: Required under state law, either directly from the outside or through a shared entry hall meeting building code egress requirements
• Setbacks: Must meet standard zoning requirements for the applicable district; cannot be more restrictive than what applies to the principal dwelling or accessory structures
• Height: Must comply with district height limits
• Building code: Must comply with 780 CMR Massachusetts State Building Code
• Types: Attached, detached, and internal ADUs are all permitted under state law
• Lynn does not impose additional design standards beyond standard building, safety, and zoning requirements

• Maximum 1 parking space may be required for the ADU under state law.
• 0 parking spaces required if the property is within 0.5 miles of a commuter rail station, subway station, ferry terminal, or bus station.
• Lynn is served by the MBTA Commuter Rail (Lynn station on the Newburyport/Rockport Line) and MBTA bus routes. Many properties in Lynn may qualify for the transit exemption.
• Lynn does not impose additional parking requirements beyond the state maximum.

• Groundwater Protection District: Lynn has a Groundwater Protection District that may affect ADU development in certain areas. This district may impose additional limitations on bedrooms and development intensity where groundwater protection is a concern. Homeowners should check with the Inspectional Services Department or review the zoning map to determine if their property falls within this district.
• No local ADU ordinance: Lynn follows state defaults entirely. This means the permitting process should be relatively straightforward, with fewer local complications compared to municipalities that have their own ADU bylaws with potentially conflicting provisions.
• Transit proximity: Lynn has an MBTA commuter rail station and multiple bus routes. Properties within 0.5 miles of these transit stops are exempt from any parking requirement for the ADU.
• 15 zoning districts: The City of Lynn divides the community into 15 zoning districts. Confirm which district your property is in and review applicable dimensional requirements (setbacks, lot coverage, height) via the zoning map available on the city's website.
• Zoning Board of Appeals: Meets 1st and 3rd Tuesday of each month at 7:30 PM, City Hall Room 302. Relevant for properties requiring dimensional variances (not for ADU use itself).

Lynn does not have a dedicated ADU bylaw section. The following is the complete information available from the City of Lynn's zoning and ISD pages as compiled from available sources:

CITY OF LYNN -- ADU INFORMATION

OVERVIEW:

Lynn allows ADUs under Massachusetts' statewide rule that lets homeowners build one Accessory Dwelling Unit (ADU) by right on any single-family property. Lynn follows state defaults without imposing additional local restrictions such as owner-occupancy mandates, strict architectural matching, or additional parking requirements beyond the state maximum.

ADU REQUIREMENTS (State Defaults Apply):

• One ADU per single-family lot, allowed by right
• Maximum 900 sq ft or 50% of principal dwelling, whichever is smaller
• Must meet standard building, safety, and zoning requirements (setbacks, height limits, utilities)
• Maximum 1 parking space (0 if within 0.5 miles of transit)
• No owner-occupancy requirement
• No family-member restrictions
• No special permit required
• Must comply with 780 CMR State Building Code
• Must comply with 310 CMR 15.000 (Title 5) for septic systems

IMPORTANT LOCAL CONSIDERATION -- GROUNDWATER PROTECTION DISTRICT:

Lynn has a Groundwater Protection District that may affect ADU development in certain areas. This district may impose additional limitations on bedrooms and development intensity in areas where groundwater protection is a concern. Homeowners should check if their property falls within this district before proceeding.

ZONING DISTRICTS:

The City of Lynn divides the community into fifteen (15) zoning districts as reflected upon the Zoning Map. Single-family residential districts where ADUs would be permitted by right include residential zones.

PERMITTING PROCESS:

1. Submit written request for Zoning Determination via lynnisdportal.com
2. Confirm property eligibility and zoning district
3. Apply for building permit through Inspectional Services Department
4. Comply with all building codes and safety standards
5. Obtain Certificate of Occupancy before use

ZONING RESOURCES:

• Zone Ordinance: City of Lynn Zone Ordinance (v2025-12-09 as adopted) -- Available on city website zoning page
• Zoning Map: Available as PDF (11x17 and 24x36) and Interactive Map -- Posted December 2025
• Zoning Board of Appeals: Meets 1st and 3rd Tuesday of each month at 7:30 PM, City Hall, Room 302
• Zoning Review Checklists: Available for Home and Commercial projects

CONTACT: City of Lynn Inspectional Services Department City Hall, Room 405 3 City Hall Square Lynn, MA 01901 Phone: (781) 598-4000 Zoning Determinations: lynnisdportal.com

APPEALS: Zoning Board of Appeals pursuant to G.L. c. 40A Section 8 Applications filed at Inspectional Services Department, City Hall Room 405

Lynn 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.

Lynn does not have a local ADU ordinance with provisions that conflict with state law. The city follows Massachusetts state ADU defaults under the Affordable Homes Act (H.4977 / St. 2024, c. 150) and 760 CMR 71.00.

Since Lynn relies entirely on state defaults, there are no local provisions to preempt. The state law requirements apply directly:

• ADUs up to 900 sq ft allowed by right in single-family residential districts
• No owner-occupancy requirement
• No family-member restrictions
• No special permit required
• Maximum 1 parking space (0 within 0.5 miles of transit)
• Municipalities may impose reasonable dimensional, design, and safety requirements but cannot be more restrictive than what applies to the principal dwelling or accessory structures in the district

The Groundwater Protection District overlay is a local environmental protection measure that may apply independently of ADU-specific regulations.

• City of Lynn Inspectional Services / Zoning Page: https://www.lynnma.gov/city_government/departments/isd/zoning
• City of Lynn Zone Ordinance (v2025-12-09 as adopted)
• Lynn Zoning Map (Posted December 2025)
• Massachusetts Affordable Homes Act (H.4977 / St. 2024, c. 150)
• 760 CMR 71.00: Protected Use Accessory Dwelling Units