Queen Anne's County, MD Accessory Structures: ADU Rules (2026)

Section 18:1-48 is the county's accessory apartment rule. It allows one accessory guest residence or apartment as an accessory residential use per single-family lot, and the unit is not included when calculating the total allowable number of units, so it does not eat into the lot's density. Four conditions apply. The apartment must be located within the principal dwelling structure or within an approved residential accessory structure. It cannot exceed 1,500 square feet in total floor area. Where the lot is not on public sewer, the Queen Anne's County Health Department must approve it. The fourth condition, owner residence, is covered on its own page.

The accessory structure route connects to § 18:1-45, which sets location, area, and height limits for residential accessory structures in the same article. A related but separate use is the caretaker dwelling in § 18:1-46: one is allowed on a parcel of five or more acres, it must meet the setbacks that apply to the principal structure, and it can be no more than 50% of the area of the principal building.

Inside the Chesapeake Bay Critical Area the county code adds its own layer for the Resource Conservation Area under § 14:1-39(B)(2). One additional dwelling unit per lot or parcel counts as part of the primary dwelling for density if it is inside the primary unit or its entire perimeter is within 100 feet of the primary unit, does not exceed 900 square feet in total enclosed area, and shares the primary unit's sewage disposal system. A separate unit meeting those criteria cannot be subdivided or conveyed separately from the primary dwelling. Kent Island lots near the shoreline should read both chapters together.