The law dramatically reformed the Zoning Act as to Accessory Dwelling Units (ADUs) As-Of-Right. This permits ADUs (≤900 SF) to be built by-right in single-family zoning districts in all communities. These provisions are effective already.

The law also contains a program for Seasonal Communities Designation. This created the framework for designating communities with substantial seasonal variations in employment and housing needs to develop policies and programs targeting seasonal communities. These provisions depend on whether, when, and which municipalities adopt this status.

The author’s PowerPoint on these subjects is available on this website as linked below. In this article we present the two essentials.

First, we discuss the Seasonal Communities program. The goal is to unlock housing production opportunities to house the year-round, essential workers who either can’t afford the available homes or there are not enough homes available for these workers to purchase or rent.

A Seasonal Community is empowered to:

• (i) acquire year-round housing occupancy restrictions for rental or other housing;
• (ii) acquire and develop housing units with preference for housing seasonal community public employees that are necessary to the health and safety of maintaining a year-round community, including teachers, public works employees, public safety employees, first responders, town administrators and other employees essential for municipal operations;
• (iii) expend funds to develop, on a biannual basis, a comprehensive housing needs assessment;
• (iv) establish a Year-Round Housing Trust Fund, individually or with other seasonal communities, to provide for the creation and preservation of affordable and attainable housing in seasonal communities for the benefit of year-round residents; and
• (v) expend funds designated for the creation and preservation of year-round affordable and attainable housing for individuals who, by vocation, produce or support artistic and literary activities

Residential uses shall be permitted as of right on Undersized Lots if:

• the use is for an “Attainable Housing Unit” (Year-round Housing Unit subject to a restriction in its chain of title to income that does not exceed 250% AMI);
• located in a Single-family Residential Zoning District;
• complies with any applicable floor-to-area ratio requirements;
• complies with wastewater and sewer requirements; and
• is not used as a seasonal home or short-term rental for less than 6 months in a year.

Secondly, we turn to the dramatic changes in the Zoning Act for Accessory Dwelling Units (ADUs). An ADU is defined as self-contained housing unit, inclusive of sleeping, cooking, and sanitary facilities on the same Lot as a Principal Dwelling, subject to otherwise applicable dimensional and parking requirements, that:

• maintains a separate entrance to meet the requirements of the state building code for safe egress (going through the main dwelling’s kitchen is not an egress)
• is not larger in gross floor area than 1/2 the gross floor area of the principal dwelling or 900 square feet, whichever is smaller; and
• is subject to such additional restrictions as may be imposed by a municipality including additional size restrictions, and restrictions or prohibitions on Short-term Rental.
• Gross Floor Area (GFA): The sum of the areas of all stories of the building of compliant ceiling height pursuant to the Building Code, including basements, lofts, and intermediate floored tiers, measured from the interior faces of exterior walls or from the centerline of walls separating buildings or dwelling units but excluding crawl spaces, garage parking areas, attics, enclosed porches and similar spaces. Where there are multiple Principal Dwellings on the Lot, the GFA of the largest Principal Dwelling shall be used for determining the maximum size of a Protected Use ADU.
• Single-family Residential Zoning District: Any Zoning District where Single-family Residential Dwellings are a permitted or an allowable use, including any Zoning District where Single-family Residential Dwellings are allowed as-of-right or by Special Permit.
• “No zoning ordinance or by-law shall prohibit, unreasonably restrict or require a special permit or other discretionary zoning approval for the use of land or structures for a single accessory dwelling unit, or the rental thereof, in a single-family residential zoning district.
• May be subject to reasonable regulations, including, but not limited to, 310 CMR 15.000 et seq. [Title 5 – septic], site plan review, regulations concerning dimensional setbacks and the bulk and height of structures and may be subject to restrictions and prohibitions on short-term rentals.
• Municipalities shall not put a cap or limit on the number of Protected ADUs that may be permitted in the municipality; cannot require owner occupancy of the ADU or principal dwelling unit; cannot require more than 1 additional parking space; cannot require any parking if within .50 of a “Transit Station” (subway, commuter rail, ferry, bus).
• More than one Protected Use ADU requires a special permit

Municipalities are required to update their zoning bylaw and ordinances to incorporate and codify these Zoning Act amendments on ADUs. Specifically, they must:

• Update zoning bylaw/ordinances to reflect these changes in state law; and
• Implement “reasonable regulations” under their zoning bylaw/ordinance

For questions about ADUs and inquiries about legal services, including the status of the state ADU regulations, state published policies, and court rulings on the new laws and rules, please contact us through the Contact function on this website.

Meanwhile, you may visit the Archives on this site to see Ms. Quijada’s PowerPoint on ADUs, presented in November 2025 at the MACC Fall Conference at Devens and the REBA Annual Meeting and Fall Conference in Norwood, MA.

Visit the Presentations >>