Baltimore County, MD Environmental Rules: Flood Elevation Requirements (2026)

Section 32-8-201(dd) defines "flood protection elevation" as the base flood elevation plus two feet of freeboard, a built-in safety margin against wave action, obstructed bridge openings, debris and ice jams, climate change, and watershed urbanization that the FEMA base flood number alone does not capture. Section 32-8-504 turns that definition into a hard construction standard for residential structures and residential portions of mixed-use buildings: the lowest floor, including any basement, must sit at or above the flood protection elevation, and basement floors that are below grade on all sides are prohibited outright, with no exception.

In Zone AO areas of shallow flooding, where the FIRM shows a depth number rather than a mapped base flood elevation, the lowest floor must be elevated at least as high above the highest adjacent natural grade as that depth number plus two feet, or at least four feet if no depth number is shown. If fill is used to reach the required elevation, Section 32-8-504(b) requires it to be earthen soil or rock only, sloped no steeper than one foot vertical to three feet horizontal, and protected against erosion.

Enclosures built below the lowest floor may be used only for parking, building access, or limited storage, must use flood damage-resistant materials, and need at least two flood openings on different walls sized to at least one square inch of net opening per square foot of enclosed area. Nonresidential buildings get an alternative under Section 32-8-505: dry floodproofing to the flood protection elevation plus one additional foot, engineer-certified and paired with an operations and maintenance plan.