Simsbury zoning commission delegates ADU approvals to staff, adopts new measurement rule excluding finished basements and screened porches

The Zoning Commission on Feb. 3 approved amendments to accessory dwelling unit (ADU) rules that give town staff the authority to administratively review and approve both attached and detached ADUs and adopted a new measurement rule for calculating allowable ADU size.

Commissioners said the changes aim to reduce process barriers for homeowners seeking ADUs while maintaining regulatory safeguards. Town staff presented the amendments as a package that replaces the current requirement for site-plan review or a special exception with an administrative, staff-level zoning approval if the application meets the ADU standards in the regulations.

George (Town Planner/Staff member) reminded the commission of procedural limits in deliberations and clarified that "Public hearing is closed. That means that unseated alternate may not participate in discussion. Staff may only answer questions to provide clarification or to review previously presented material." He also reviewed the recommended change to use the zoning regulation definition of "gross building area" instead of the undefined term "gross floor area." The suggested definition sums horizontal floor areas of enclosed floors and excludes parking-deck and basement areas used for storage, loading or mechanicals.

Commissioners debated whether finished basements and enclosed screened porches should count toward the gross building area. Several commissioners said finished basements can affect the apparent scale of a house and that using an existing defined term from the zoning regulations was preferable. Others argued that counting finished basements could create inequities between houses with similar footprints. The majority supported exempting finished basements and enclosed screened porches from the calculation in order to keep ADU sizing more consistent across housing types.

On the procedural change to delegate approvals, commissioners split over whether removing a public hearing would reduce opportunities for neighbor input. Supporters argued that ADUs are tightly circumscribed by the regulations and that applications that meet the standards should not be delayed by the hearing process; opponents said retaining public hearings helps surface legitimate neighborhood concerns. Commissioners noted that applicants dissatisfied with an administrative decision may pursue relief through the Zoning Board of Appeals.

Votes at the meeting recorded two separate motions related to ADU matters. A motion to adopt the gross building area definition and to explicitly exclude finished basements and enclosed screened porches passed 5–1. A second motion to revise Section 3.5 to allow administrative approval of both attached and detached ADUs passed 4–3; the change takes effect immediately pending the statutory appeal period.

The commission asked town staff to include ADU activity in periodic planner updates so the commission can monitor the effect of delegating approvals.

The commission's action amends the ADU review and measurement provisions in the zoning regulations as set out in the staff memorandum dated Dec. 2, 2024.