A solution to the state’s current lack of affordable housing could be as close as your basement or back yard.

Residents in Norfolk and Wrentham are starting to explore the option of Accessory Dwelling Units (ADUs). Meanwhile, local officials, and construction firms, are on the ground floor when it comes to state regulations that became law in February 2025.

“A lot of people don’t even know about the ADU yet. We think it’s a viable way for property owners and families to be able to afford having their own living space on the same property,” said Charles J. Fruci Jr., owner of Wrentham-based Distinctive Creations Inc., a construction and remodeling company that builds ADUs.

According to Rachel Benson, Wrentham’s director of Planning and Economic Development, the town has approved six ADU projects so far. Norfolk’s director of Planning and Development, Richard McCarthy, said the town received its first application in February.

What is an Accessory Dwelling Unit?

An ADU can be a part of the main house (garage, basement, etc.) or may be detached. It must include sleeping, cooking and sanitary facilities, as well as a separate entrance. It can be no larger than one-half of the gross floor area of the main dwelling, or 900 square feet, whichever is smaller. There is no owner-occupancy requirement.

As part of the state’s Affordable Homes Act, ADUs are now allowed “by right.” That means an application would not require a special permit, variance, zoning amendment or waiver. It would require a site plan review process, and the ADUs must meet local and state building and sanitary codes.

“Massachusetts needs more homes to drive down costs for everyone. That’s why, with the Legislature, we legalized ADUs by right in the Affordable Homes Act,” said Governor Maura Healey in a press release from September 2025. “ADUs can help seniors afford to stay in the communities they love, give families a chance to earn some extra income, or provide an individual with disabilities more independence.”

Although in its early stages, ADUs could become a major factor in home construction and renovation, according to Fruci. “Unlike ‘in-law additions,’ ADUs can be built and rented out to family or complete strangers for additional income. We believe these ADU projects will take off and become over 50 percent of our work load in the near future,” he said.

Currently, Distinctive Creations has three ADU projects, all in the design or permitting phases. Fruci estimated it would take about six months from getting the building permit to completion.

“These projects are like building a small house,” he said.

Costs for an ADU can vary depending on the project, Fruci added. Distinctive Creations budgets an average starting cost of $350-$400 per square foot.

“In theory, building an ADU within the existing footprint of a home should reduce costs because you avoid expenses like sitework, concrete and new foundation work. However, interior conversions come with their own challenges that can offset some of those savings,” he said.

“For example, if the ADU is created in an existing basement, the building code requires two means of egress dedicated to that unit. One of those exits cannot be through the main house. That means you’d need either two bulkhead-style egress points for a full foundation, or two exterior doors for a walkout basement. Additionally, the separation between the ADU and the existing living space must meet two family or multifamily fire separation requirements, which typically means fire rated ceilings and or walls depending on the layout.

“So, while an ADU within the existing footprint can be less expensive overall, the actual cost depends heavily on the existing conditions of the house and property. Every location — basement, first floor, attic or addition — comes with its own set of challenges, code and construction considerations,” Fruci added.

The Local Regulations

As part of the amendment on ADUs passed by Norfolk’s Annual Town Meeting in 2025, an ADU is not to be used as a short-term rental, and must remain an accessory to the principal dwelling (no separate ownership). One ADU is allowed by right per lot; a special permit is required for the use of land or structures in a single-family residential zoning district for more than one accessory dwelling unit. There should be an additional 10,000 square feet of land for any additional ADU, with a maximum of two ADUs.

If the ADU is within a half-mile radius of a transit station in Norfolk, such as Commuter Rail, no additional parking spaces would be required. If outside that radius, the ADU must include one private off-street space (a waiver may be granted by the Planning Board if the applicant can prove the parking space is not needed).

Wrentham also amended its zoning bylaws regarding ADUs during its Annual Town Meeting in 2025. Additional adjustments – including proposed ADUs on non-conforming lots – is part of a draft article for this year’s Annual Town Meeting in June.

According to its zoning bylaws, only one ADU may be created within a single-family dwelling. The ADU can have no more than two bedrooms, and may be occupied by someone providing medical or custodial care to an occupant of the main dwelling. Also, any entrances to the ADU must be on the side or the rear of the building. As in Norfolk, ADUs may not be used for short-term rentals.

In both communities, ADUs must meet local and state building and sanitary codes.

While ADUs would count toward a community’s year-round housing stock, they would not count toward a community’s affordable housing as it relates to Chapter 40B, according to Benson.

“Chapter 40B requires that a city/town has to have at least 10 percent of its year-round housing stock be Deed-Restricted Affordable, better known as its Subsidized Housing Inventory (SHI),” she said. “However, ADUs do count towards a municipality’s year-round housing stock, so those units bring the denominator number up in that percentage calculation.”

She added that Wrentham has about 11.7 percent of its housing stock as deed-restricted affordable, so it currently meets the 40B requirements. According to McCarthy, Norfolk has 4.96 percent of its units listed on its SHI.

The Process

McCarthy said Norfolk residents should set up a meeting with the town’s building commissioner to help determine if the ADU could be built within the house, or as a detached unit.

If the ADU would be within the house, with no external change, the resident would work with the Building Department; this would include a determination of applicability to figure square footage. A detached ADU would go through the site plan review process.

In Wrentham, applications for ADUs, including a site plan and architectural drawings, would go through the Building Commissioner; the applications must be consistent with the submission requirements of the rules and regulations of the Zoning Board of Appeals.

Once the process becomes more refined, Fruci said ADUs could become a more feasible option for homeowners.

“We believe the flexibility of the ADU being able to go almost anywhere (within the zoning and codes) will eventually make it easier for parents, siblings and family to afford today’s living cost and if renting the ADU collect some additional income,” he said.