St. Mary's County commissioners approve first reading of accessory dwelling unit zoning amendment, send changes to Planning Commission

The St. Mary's County Board of County Commissioners voted Sept. 4 to approve a first reading of a zoning text amendment addressing accessory dwelling units (ADUs) and directed county staff to forward the draft to the Planning Commission for review and recommendation.

County planning staff told commissioners the number of ADUs in the county has increased recently, and that some are being used as de facto duplexes or rental properties rather than accessory units occupied by owners or family members. Commissioners said the draft amendment should close an apparent loophole that allows properties within newly developed subdivisions to effectively double occupancy and demand on public facilities without prior Adequate Public Facilities (APF) review.

Planning staff proposed language to require that, for ADUs built after the amendment's effective date, either the principal dwelling or the accessory unit be occupied by the lot owner. Staff and the county attorney noted enforcement challenges and discussed possible mechanisms such as conditional-use approvals through the Board of Appeals or an affidavit recorded in the land records to bind future owners. Commissioners also discussed a suggested five-year residency concept and the need to protect legitimate family uses—such as elderly parents living on-site or military families who temporarily relocate.

Commissioners asked whether utilities are required to be on separate meters for accessory units; staff said that could vary (attached ADUs commonly remain on a single meter; detached units might have separate meters). Staff emphasized that because ADUs are accessory uses, APF review typically occurs at subdivision and initial permit stages and ADUs built later may not trigger additional APF review unless the ordinance is changed.

Commissioner Raley moved to accept and approve the first reading and to authorize staff to proceed to the Planning Commission and to inform that body of the concerns discussed at the Sept. 4 meeting; Commissioner DeMitt seconded. The motion carried.

The board instructed staff to craft clearer, enforceable language that preserves legitimate owner‑occupied and family-use ADUs while limiting the risk that investors could convert lots into rental pairs that exceed the infrastructure and neighborhood design assumptions of initial subdivision reviews. Staff will return with Planning Commission recommendations and any suggested amendments.

For transparency, the board's first-reading approval does not change ordinance text; it only authorizes the formal review process with the Planning Commission and further work on enforcement language.