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Lynn, MA Accessory Structures: ADU Rules (2026)

Some Restrictions

Compiled from the official code textEditor Martyn O'NeillLast verified September 2026

ADU rules in Lynn, MA, also called accessory dwelling unit regulations or granny flat ordinances, cover setbacks, owner-occupancy, parking, and permit requirements.

Key Facts

By Right: One ADU, single-family lots
Adopted: February 11, 2025
Max Size: 900 sq ft or 50% of home
Parking: 1 space (transit waiver)
Short-Term Rental: Prohibited under 28 days

ADU Eligibility Quick-Check

An Accessory Dwelling Unit (ADU) is a smaller, independent living unit on the same lot as a single-family home: converted garages, detached cottages, basement or attic conversions, and attached additions all qualify. Most states have streamlined ADU permitting since 2020, but local rules still control size, height, and setback.

Is your lot zoned single-family or multi-family residential?
Does your lot have at least 1,200 sq ft of buildable space?
Is your existing home owner-occupied (in most states this is not required, but some require it for ADU permits)?
Will the ADU stay under your state's size cap (commonly 850-1,200 sq ft for detached)?
Can you provide one off-street parking space (waived in many states within 0.5 mi of transit)?

If you answered 'yes' to most of these, you likely qualify in Massachusetts under recent ADU streamlining laws. The Lynn, MA rules below cover local size, height, and setback requirements.

Summary

Lynn allows one accessory dwelling unit by right on single-family lots, adopted February 11, 2025 under the state Affordable Homes Act. An ADU may not exceed 900 square feet or 50% of the main home's floor area.

By right. Subject to the requirements of this Ordinance, one accessory dwelling unit is allowed as of right on property located in a single-family residential zoning district, either within a principal dwelling or in a structure accessory thereto.

Source: City of Lynn Revised OrdinancesView official code

Official source re-checked September 8, 2026: the cited page had not changed since it was quoted.

Full Breakdown

Lynn amended its zoning on February 11, 2025 to permit ADUs, matching the statewide 2024 Affordable Homes Act. Under the 2025 Lynn Zoning Ordinance (Section 9.B), one ADU is allowed as of right in single-family districts, within the home or an accessory structure; a Special Permit is needed for more than one. An ADU may not exceed the lesser of 900 square feet or 50% of the principal dwelling's gross floor area, and a detached ADU up to 15 feet tall follows accessory-structure dimensions. One parking space is required unless the lot sits within a half-mile of a commuter rail, subway, ferry, or bus station. ADUs cannot be rented short-term (under 28 days) or occupy RVs or structures on wheels.

Violations & Fines

Lynn cannot deny a conforming by-right ADU. Building an ADU without permits draws standard 780 CMR enforcement; renting an ADU for under 28 days violates the ordinance's short-term-rental prohibition.

Frequently Asked Questions

Can I build an ADU in Lynn?

Yes. Since February 2025, one ADU is allowed by right on single-family lots, up to 900 square feet or 50% of your home's floor area, whichever is smaller.

Do I need an extra parking space?

Usually one, but not if your property is within a half-mile of a commuter rail, subway, ferry, or bus station. The City Council can waive it by Special Permit.

Sources & Official References

[1]City of Lynn Revised Ordinances

Other rules in Lynn

Parking Rules: Overnight ParkingSignificant Restrictions Shed & Carport RulesSome Restrictions Tiny HomesSome Restrictions Noise Ordinances: Decibel LimitsSome Restrictions Parking Rules: Driveway RulesSome Restrictions Parking Rules: EV ChargingSome Restrictions Parking Rules: Loading ZonesSome Restrictions Parking Rules: Snow Removal Parking RulesSome Restrictions

All Lynn rules

Compare Lynn to another location·View the Massachusetts accessory structures overview

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