AMHERST — The Zoning Board of Appeals has ruled that an accessory dwelling unit under construction at 27 Newell Court is too large under the town’s zoning bylaw, ordering developer Alan St. Hilaire to either shrink the unit’s living space or have an owner live on site.

The board’s unanimous vote at its Thursday, Aug. 13 meeting, acting on a petition brought by neighbor Noah Kuhn of 9 Newell Court, overturned a May 4 decision by Building Commissioner Rob Morra, who had excluded attic space from the project’s gross floor area calculations. The board upheld a related May 12 decision by Morra finding that the accessory dwelling unit did not comply with the zoning bylaw.

The five-member panel’s ruling means St. Hilaire may need to take corrective action: either shrinking the unit’s livable space to 900 square feet or less by removing the bedrooms, closets and bathroom from the attic, or changing the new building from a so-called “protected ADU” to a “local ADU,” which would require St. Hilaire, as the property owner, to live in either the principal dwelling or the accessory unit.

Michael Pill, representing St. Hilaire, said he will likely file a lawsuit, observing that his client, who lives in Hadley, is being sabotaged by an illegal decision, in part because Kuhn didn’t have standing.

“This is not only an illegal decision, but a serious case of injustice,” Pill said.

At the center of Kuhn’s appeal was whether an additional 200 square feet of upper-level space should count toward the unit’s 891-square-foot total. Morra excluded that space under the building code’s “attic exclusion approach,” which allows upper-level space to go uncounted as long as it’s less than one-third the size of the main living area below it.

Chairman Everald Henry said in his legal analysis that this was an attempt to get extra living space without abiding by the 900-square-foot protected ADU limit, adding that the size limitation is the only protection for residents who live near these developments.

What Morra had termed bonus space, Henry said should be seen only as a bonus for developers, not for the people who live next door.

David Sloviter, the Zoning Board of Appeals vice chairman, said there is no provision in the bylaw for bonus space, and that the only way to permit 1,200-square-foot ADUs is for property owners to live in the principal or accessory dwelling.

He said it was common sense that an attic isn’t livable space. “An attic is an attic is an attic,” Sloviter said.

Board member Sarah Morton said she reached out to the Executive Office of Housing and Livable Communities for an opinion. She was informed that an attic is not a space connected to a bedroom. Morton wanted the board to state that attics aren’t livable space, though that was not included in the decision.

Board member David Ahlfeld initially appeared inclined to support Morra, noting that the building commissioner hadn’t made an error, and that it was up to the Town Council to “get it together” to fix problems with the ADU bylaw and clarify how space is counted.

The board should determine if Morra got it right or wrong, said board member Craig Meadows. “In this case, the commissioner got it wrong,” he said.

Pill elaborated on his concerns that the Zoning Board of Appeals made an ill-advised decision, which could impact several other developers who are providing new housing opportunities in town.

“The analysis by Building Commissioner Rob Morra is the correct analysis, and that should have been affirmed,” Pill said.

There is also a question about whether Kuhn had standing and was impacted or injured by the project. Pill said Kuhn didn’t appeal the building permit when issued, and that the statute of limitations, which extended for 30 days, had expired last December. What happened before the Zoning Board of Appeals was an “illegal ambush” on St. Hilaire, Pill said.

Scott Merzbach is a reporter covering local government and school news in Amherst and Hadley, as well as Hatfield, Leverett, Pelham and Shutesbury. He can be reached at smerzbach@gazettenet.com or 413-585-5253.