Carroll County directs staff to draft ADU code changes to comply with Maryland law

Planning staff told commissioners the Maryland General Assembly passed HB1466 (2025), which requires jurisdictions to adopt local code amendments to allow accessory dwelling units — secondary units on the same lot as a single-family residence — and to align local definitions and standards with the state framework by Oct. 1.

"House Bill 1466 ... requires all jurisdictions adopt a local law authorizing ADU or accessory dwelling units ... an ADU is considered a secondary unit on the same lot... and it must not be greater than 75% of the primary unit," staff explained.

Staff outlined that jurisdictions must permit ADUs that meet health and safety standards, exempt ADUs from density calculations, and cannot impose parking or rear/side setback requirements that exceed accessory-structure rules unless a parking study justifies those standards. Staff also noted the county will need to consider interactions with its adequate public facilities ordinance (APFO), septic systems in rural areas and potential owner-occupancy or rental outcomes.

Commissioners raised concerns about impacts on HOAs, septic capacity, sprinkler requirements for additions, and the risk that ADUs could be commercialized into rental units. After discussion, the board voted to direct staff to coordinate with the Planning & Zoning Commission to draft a text amendment and return with recommendations, analysis of APFO implications and suggested protections.

No final code changes were adopted at the meeting; staff will prepare drafts, analyses and a public-notice timeline for future hearings.