Are Amherst Developers Flouting the Intent of the Town’s ADU Bylaw?

A building boom of accessory dwelling units (ADUs) is underway in Amherst, with at least 21 permits for new units issued in the last five months and another five to seven applications pending. Plans for several of those units appear to violate the town’s new ADU bylaw. ADUs are self-contained units with sleeping areas, eating areas, and bathrooms on a lot that also contains a principal dwelling.

After lengthy deliberation, the town adopted in November 2025 (see also here) a two-tiered bylaw governing accessory dwelling units to conform with a new state law. The state law allows ADUs of up to 900 square feet — defined as “protected” ADUs — to be built by right with few limitations on design, dimensions, or number of inhabitants. Permits for such units are issued by the town’s building commissioner without notifying abutters or holding a hearing before town committees or boards. Amherst’s bylaw also allows ADUs up to 1,200 square feet, known as “local” ADUs, if either the ADU or the principal dwelling is owner-occupied. The larger ADUs must also conform to design and dimensional requirements (see Amherst Zoning Bylaw 5.011).

Based on plans filed with the town, at least nine of the recently permitted “protected use” ADUs are substantially larger than the 900 square feet allowed. Their ground floors measure just under 900 square feet, but their second floors include about 300 square feet of finished habitable space. Plans for ADUs on Chestnut, Taylor, and Gray streets and Newell Court show two bedrooms with walk-in closets and a bathroom on the second floor, a stairway from the first floor, and ceiling heights above 8 feet. If that finished upstairs space is included in the calculation of gross floor area (GFA), those plans would not qualify for permitting as protected ADUs under the bylaw.

Neighbors of some of these ADUs have raised the apparent violation with Building Commissioner Rob Morra. Morra told the Indy that his interpretation is that the second floor constitutes attic space and should not be included in the GFA calculation. He noted that state regulations do not define “attic,” but Amherst’s Zoning Bylaw (Section 6.18) does, and it excludes attic space from the GFA calculation. The bylaw states:

“A half-story in a top floor shall be a lawful habitable space with required means of access and egress and in which a minimum seven (7) foot floor-to-ceiling height exists in at least half of the habitable floor area but no less than one-third of the habitable floor area of the full story below.”

The bylaw actually contains no formal definition of “attic,” but it does define “story.” Morra has determined that an upper floor that does not meet the definition of a story is, by default, an attic — and that any space smaller than one-third of the habitable area below does not qualify as a story and is therefore an attic, and hence excluded from the GFA. He said the original approved designs for the ADUs noted above were adjusted to reduce the bedroom sizes so that the second floor now measures 291 square feet, falling under his definition of an attic.

According to ADU Zoning Bylaw Section 5.011: “The following definitions apply. a. Gross Floor Area: 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.” Compliant ceiling height is defined as ceilings over 7 feet, but Morra considers the second floors of these ADUs to be attics and therefore exempt from the compliant ceiling height provision.

The Intent of the Bylaw: More ADUs
The stated purpose of easing ADU requirements is to “allow the Town of Amherst to expand and diversify its housing supply by making efficient use of available land without requiring the creation of new lots. Accessory Dwelling Units are intended to meet the changing housing needs of the community by providing smaller units in existing residential neighborhoods.” (Zoning Bylaw 5.0110)

During deliberations on the new bylaw, the Planning Board and Community Resources Committee (CRC) raised concerns about the proliferation of these units for college student housing in largely residential neighborhoods. They believed that the restricted size requirements would limit the number of occupants. If those size restrictions can be expanded through what critics call an “attic loophole,” the number of residents could be substantially larger than intended, potentially straining neighborhoods that are already densely populated and have limited parking.

Morra told the Indy that the question of allowing additional living space came up during the CRC’s deliberations. Early drafts of the bylaw defined GFA as all habitable space, but the town’s attorney, KP Law, advised but the town’s attorney, KP Law, advised Morra and planner Nate Malloy that including that provision could draw objections from the state attorney general.” The “habitable space” language was removed late in the process, before the bylaw was passed by the Town Council. Morra said the town sought an opinion from the attorney general but did not receive a response.

CRC Chair Pam Rooney disputes Morra’s assertion that councilors were informed of this loophole. In an email to the Indy, she wrote: “No one ever said, during our adoption process, are you aware that in applying the state definition, a builder is allowed to include up to one-third of the dwelling’s main floor area as finished, usable attic space and that won’t count toward their total square footage? Therefore, an ADU could contain 900 square feet on the main floor plus up to 300 square feet of attic space. Is that what you, council members, want?”

She maintained that, like a finished loft, a finished attic should be included in the GFA.

Morra said the town managed ADUs well under the previous bylaw and that the new state law has made things more complicated. He maintains that he is obligated to accept the submitted plans under the new bylaws. “For our town and the issues we deal with, this is unfortunate,” he said. “The state law gives us no ability to adjust to our needs. The Cape and Islands were given some flexibility to meet their needs, but we weren’t given that flexibility.” He said he advised the CRC: “We have to do this, but let’s put in safeguards. But our ability to do that was limited.”

When asked what recourse the town has, Morra said Amherst could appeal to the Executive Office of Housing and Livable Communities (EOHLC), which enforces the state bylaw, but that a response could take years. Residents could also appeal to the Legislature through state Rep. Mindy Domb. He said the simplest and most expedient fix would be to amend the definition of “attic” in the Zoning Bylaw to cover only uninhabitable space. That change would also apply to single-family homes but could serve as an interim measure until the problems with the state bylaw are resolved.

In the meantime, the proliferation of larger ADUs with no cap on number of occupants raises a number of questions for affected neighborhoods. How will these structures be taxed — as two-bedroom, 900-square-foot units or four-bedroom, 1,200-square-foot units? (The difference appears to be roughly $3,000 in annual tax revenue per unit.) Will the building commissioner ensure that basements are not also rented out? What is the parking plan for these new units? A protected-use ADU may not have more than three parking spaces under the bylaw, and street parking in downtown neighborhoods is already limited. How do the framers of the town bylaw feel about effectively permitting four-bedroom homes under the protected ADU provision, and what do they believe should be done?

Building Commissioner’s Decision Appealed to Zoning Board of Appeals
An abutter to one of the two-story ADUs currently under construction filed a complaint with the building commissioner. Morra upheld his permitting decision after requiring the second-floor area to be reduced. The matter has since been appealed to the Zoning Board of Appeals.

The Amherst ADU Bylaw.
Here is the complete text of the Amherst ADU Bylaw

 5.011 Accessory Dwelling Units (Amended November 17, 2025; Effective December 1, 2025) 5.0110 Purpose Accessory Dwelling Units allow the Town of Amherst to expand and diversify its housing supply by making efficient use of resources without requiring the creation of new lots. Accessory Dwelling Units are intended to meet the changing housing needs of the community by providing smaller units in existing residential neighborhoods.

5.0111 Applicability The Town of Amherst permits two types of Accessory Dwelling Units (ADU): a Protected Use ADU in accordance with MGL c. 40A §3 and 760 CMR 71.00, and a Local ADU. Both types of ADUs shall be permitted in any single-family residential zoning district that allows a detached single-family dwelling by right or by Special Permit, including the RO, RLD, RN, RVC and RG zoning districts.

 a. A Protected Use ADU shall meet the State definition per MGL c. 40A §1A, as well as State regulations under 760 CMR 71.00. The use of land or structures for a Protected Use ADU -64- shall be as-of-right, meeting all requirements associated with the issuance of a building permit and meeting certain requirements listed in this section of the Zoning Bylaw.

b. A Local ADU shall meet the definition and specific requirements in this section of the Zoning Bylaw. The permitting of a Local ADU shall follow these steps: a. When a lot has no ADU, the Local ADU shall require Administrative Approval according to Section 11 of the Zoning Bylaw; or b. When a lot has a Protected Use ADU, the Local ADU requires a special permit from the ZBA

c. Either ADU type may be completely contained within the Principal Dwelling, attached to a Principal Dwelling, detached as a separate building or within a detached structure (e.g. above an existing detached garage). Any ADU may be within an existing building or new construction. 5.0112 Definitions For the purposes of this section of the Zoning Bylaw, the following definitions shall apply. a. Gross Floor Area: 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 Gross Floor Area of the largest Principal Dwelling shall be used for determining the maximum size of a Protected Use ADU.

b. Principal Dwelling: In accordance with 760 CMR, a Principal Dwelling shall mean a structure, regardless of whether it, or the lot it is situated on, conforms to zoning, that contains at least one dwelling unit and is, or will be, located on the same lot as the ADU.

c. Protected Use Accessory Dwelling Unit: Per MGL c. 40A §1A, a Protected Use ADU is a self-contained residential dwelling 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: (i) maintains a separate entrance, either directly from the outside or through an entry hall or corridor shared with the Principal Dwelling, that sufficiently meets the requirements of the state building code for safe egress; (ii) is not larger in Gross Floor Area than half (1/2) the Gross Floor Area of the Principal Dwelling or nine-hundred (900) square feet, whichever is smaller; and (iii) is subject to additional requirements found in this section of the Zoning Bylaw.

d. Local Accessory Dwelling Unit: An ADU that is not a Protected Use ADU. A Local ADU shall be a self-contained residential dwelling unit, inclusive of sleeping, cooking, and sanitary

facilities on the same lot as a Principal Dwelling that: (i) maintains a separate entrance, either directly from the outside or through an entry hall or corridor shared with the Principal Dwelling, that sufficiently meets the requirements of the state building code for safe egress; (ii) is larger in square feet than a Protected Use ADU but shall not be larger than 1,200 square feet of Gross Floor Area; and (iii) is subject to additional requirements found in this section of the Zoning Bylaw.

 5.0113 General Requirements for Protected Use Accessory Dwelling Units and Local Accessory Dwelling Units a. All ADUs shall be located on the same lot as the Principal Dwelling. b. There shall be no more than one Local ADU and one Protected Use ADU permitted on the same lot as the Principal Dwelling. c. All ADUs are exempt from the additional Lot Area/Family requirements of Table 3, Dimensional Regulations. -65- d. No additional or separate driveway curb cut to serve any ADU shall be permitted unless approved by the Department of Public Works. e. A parking plan shall be submitted to and approved by the Building Commissioner, and shall be in accordance with the Design and Landscape Standards of Section 7 of the Zoning Bylaw. f. If the Principal Dwelling and/or any ADU will be rented, any rental unit shall be registered and permitted in accordance with the Residential Rental Property Bylaw of the General Bylaws. g. All exterior lighting shall be designed and installed so as to be shielded, downcast, and darksky compliant to avoid light trespass onto adjacent properties. h. On-site storage and management of waste and recycling shall be located on the interior of the dwelling, within an attached garage or other accessory outbuilding, or screened appropriately from public view. i. There shall be no more than two on-site parking spaces provided for any ADU. j. To the extent feasible, a newly constructed detached ADU shall be located behind the front building line of the Principal Dwelling closest to the street. 5.0114 Specific Requirements for Protected Use Accessory Dwelling Units a. There is no minimum lot size required for a Protected Use ADU. b. The more permissive (i.e. least restrictive) dimensional regulations found in Article 6 of the Zoning Bylaw for a detached single-family dwelling, the Principal Dwelling or an accessory structure, shall apply to the Protected Use ADU. c. In accordance with 760 CMR, no parking space shall be required for a Protected Use ADU located within ½ mile of a commuter rail station or bus stop.

5.0115 Specific Requirements for Local Accessory Dwelling Units

 a. Either the Principal Dwelling or the Local ADU shall be occupied by the owner(s) as their Principal Residence. This owner occupancy requirement shall be made a condition of an approval by the Building Commissioner and restricted as such by a deed restriction filed with the Registry of Deeds.

b. A Local ADU shall be designed so that the appearance and scale of the structure is compatible with the Principal Dwelling. c. All dimensional standards found in the Zoning Bylaw, including those for accessory structures and Table 3, Dimensional Regulations, shall apply to the Local ADU, with the exception of the additional Lot Area/Family requirement. d. The Gross Floor Area for a Local ADU does not include the area of unfinished basement space used for storage or utilities