AMHERST — Amherst could become the first Massachusetts community to define student homes, giving the town some control over who will live in what are expected to be a growing number of accessory dwelling units.

With the state adopting a new law allowing accessory dwelling units, or ADUs, by right in every city and town, and eliminating an Amherst-specific requirement that one of the two units be occupied by a property owner, the Planning Board last week voted 4-3 to ask the Planning Department to craft a student home definition.

“It’s not anti-student, it’s pro permanent resident,” Planning Board member Jesse Mager said of the proposed definition, which would be used to ensure that only one of the two units, either the main house or the accessory dwelling, be occupied by students. “We want there to be more opportunities for long-term stable households.”

The vote instructs Senior Planner Nate Malloy to incorporate the definition of student home as “any dwelling unit within a one-family dwelling, a one-family dwelling with an apartment or a two-family dwelling that is occupied by persons who are unrelated by blood, marriage or legal adoption and are attending undergraduate or graduate programs offered by colleges or universities, including those on a semester break or summer break from studies.”

The definition also states that “student homes include living arrangements where the property owner(s) or their family members are residents of the dwelling unit” but excludes fraternities, sororities or rooming houses. The language is modeled after a similar regulation in State College, Pennsylvania, where Penn State University is located.

A concern for planners is that the strong demand for rental homes due to the presence of the University of Massachusetts will lead to most new accessory dwelling units being filled with student renters.

“We should have a definition of student home,” said Planning Board member Bruce Coldham. “If any community in the state should have it, we should.”

“Clearly we can’t wait for other communities around us to take the initiative here, it’s going to be up to us,” Coldham added. “I think it’s appropriate we move this forward and see how it goes.”

Also voting in favor of the recommendation were board members Mager, Fred Hartwell and Karin Winter.

But Chairman Douglas Marshall voted against the idea. “This seems like a major step in the way we’re thinking about zoning occupancy in Amherst,” Marshall said. “I’m a little bit hesitant to jump to that conclusion immediately.”

Planning Board member Johanna Neumann said creating such a definition risks making permanent residents more valuable than other people who live in town.

“We are a college town, and I’m worried that this approach could promote legal challenges, I think it distracts from other important things that we know are in our lane, I think it has potential to add cumbersome red tape and more regulations, and to me it just screams nanny state government at its worst,” Neumann said.

Supporting them in not having the definition includes was member Lawrence Kluttz.

It’s uncertain what impact having such a definition would have and whether fewer ADUs might get built. But Malloy said if a property owner is concerned about the student home rule, there would likely be an appeal to Zoning Board of Appeals, followed by taking the town to court. Malloy said the language would be vetted by town attorney KP Law to make sure it is compliant with state law. No approval is needed from the state attorney general.

“The concern is that the overwhelming demand in the market will change who occupies the ADUs and just change the housing dynamic,” Malloy said.

Mager said this shouldn’t be seen as a way to minimize disturbances and improve quality of life, but rather to bring more housing to town for long-term residents. “The point of this is not to try to fix behavior, the point of this is to increase permanent residents. Period,” Mager said.

Winter said she believes there will be an onslaught of ADUs, with property owners seeing them as an opportunity to house double the number of students, with the town currently having a cap of four unrelated individuals in a home. Whether the student home is enforceable or not, it will act as what she called a “pre-warning.” “I am very much in favor of using this time to add this,” Winter said.

District 4 Councilor Pam Rooney said she appreciates the pro-resident emphasis, while also wondering if the revised ADU bylaw can maintain the current cap in three individuals living in any accessory dwelling.

Scott Merzbach can be reached at smerzbach@gazettenet.com.