Charles County, MD Accessory Structures: Garage Conversions (2026)

700, codified at § 297-212(23). Subsection A allows an accessory apartment to be located either inside the principal dwelling or inside an accessory structure like a detached garage. Subsection E, titled 'Water and sewerage service,' is the specific approval gate for a conversion: prior to the issuance of a zoning permit for establishing an accessory apartment in an existing residential structure, or for the conversion of an existing accessory building to an accessory apartment use, the property owner must obtain approval of the proposed method of water supply and sewage disposal from the Charles County Department of Health.

That means a garage conversion cannot get a zoning permit until Health has signed off on how the new living space will get water and handle sewage, whether that is a connection to the existing house system or a separate arrangement. 700(B): a 300-square-foot minimum, no more than two bedrooms, and a cap of 50% of the accessory structure's floor area, plus the general rule that no new exterior entrance facing a road or street may be added to the building. Off-street parking for the converted unit must still meet Article XX's parking-facility standards, and only one accessory apartment is allowed per single-family lot.