Southborough planning board debates accessory-dwelling-unit draft over setbacks, parking and septic rules

The Town of Southborough Planning Board on Monday, Jan. 6, 2025 reviewed a draft accessory-dwelling-unit bylaw and accompanying regulations prepared by town counsel and discussed state regulations and local implementation steps, including a public hearing the board opened for Jan. 27.

The session focused on five practical issues: whether ADUs may be located closer to the street than the primary dwelling, parking requirements including whether tandem spaces are allowed, limits on additional curb cuts, how preexisting nonconforming structures will be treated, and Title 5 septic constraints for added living space. Planning staff said the draft bylaw and supporting documents were distributed to board members and the Zoning Board of Appeals for review and that the Commonwealth’s draft regulations (760 CMR) have an open comment period that closes Jan. 10.

Why it matters: state law broadly enables ADUs and restricts certain municipal barriers; towns that adopt local rules must conform to state regulations while balancing neighborhood character, on‑site wastewater capacity and public‑works impacts such as curb openings and driveway changes.

Setbacks and the “front yard” restriction

A central dispute concerned a provision in the town-counsel draft that would bar any portion of an ADU from being closer to the front lot line than the primary dwelling. Mike Robbins, a member of the Zoning Board of Appeals who provided written comments, said detached ADUs are likely to be rare and that a blanket front-yard ban could prevent practical accommodations, for example for an aging parent who needs street-level access.

"If you had a large piece of property ... why couldn't [a detached ADU] be in front of the house per se?" Robbins said. "If it's that homeowner's property, why should we be telling them they can't build something on their own land to that degree?"

Other planning-board members pushed back, saying the state’s intent is that ADUs remain accessory to the primary use and that towns must take care not to create regulations that would be deemed an unreasonable restriction under…