D.C. Mun. Regs. tit. 12, app 12-A-G r. 12-A-G1001
Utility and miscellaneous Group U. Utility and miscellaneous Group U includes buildings that are accessory in character and miscellaneous structures not classified in any specific occupancy in this code, including, but not limited to, agricultural buildings, aircraft hangars (accessory to a one- or two-family residence), barns, carports, fences more than 6 feet (1829 mm) high, grain silos (accessory to a residential occupancy), greenhouses, livestock shelters, private garages, retaining walls, sheds, stables and towers.
Flood loads. Utility and miscellaneous Group U buildings and structures located wholly or partially within flood hazard areas, including substantial improvement of such buildings and structures, shall be anchored to prevent flotation, collapse or lateral movement resulting from flood loads, including the effects of buoyancy, during conditions of the design flood.
Elevation. Utility and miscellaneous Group U buildings and structures located wholly or partially within flood hazard areas, including substantial improvement of such buildings and structures, shall be elevated such that the lowest floor, including basement, is elevated to or above the design flood elevation in accordance with Section 1612 of this code.
Enclosures below design flood elevation. Fully enclosed areas located wholly or partially within flood hazard areas below the design flood elevation shall be constructed in accordance with ASCE 24.
Flood-damage-resistant materials. Flood-damage-resistant materials shall be used below the design flood elevation.
Protection of mechanical, plumbing and electrical systems. Mechanical, plumbing and electrical systems, including plumbing fixtures, located wholly or partially within flood hazard areas shall be elevated to or above the design flood elevation.
Exceptions: Electrical systems, equipment and components; heating, ventilating, air conditioning and plumbing appliances; plumbing fixtures, duct systems and other service equipment shall be permitted to be located below the design flood elevation provided that they are designed and installed to prevent water from entering or accumulating within the components and to resist hydrostatic and hydrodynamic loads and stresses, including the effects of buoyancy, during the occurrence of flooding to the design flood elevation in compliance with the flood-resistant construction requirements of this code. Electrical wiring systems shall be permitted to be located below the design flood elevation provided they conform to the provisions of NFPA 70.
D.C. Mun. Regs. tit. 12, app 12-A-G r. 12-A-G1001