Alexandria, VA Environmental Rules: Flood Elevation Requirements (2026)

Section 6-307 spells out the elevation math that applies once a parcel's base flood elevation (BFE) has been established from FEMA's Flood Insurance Study or a certified engineering analysis. Residential buildings, including additions and accessory structures, in Zones A, AE, and AH must have their lowest floor, basement included, elevated to or above the BFE plus one foot; no building permit for a substantial improvement of an existing home can issue unless that freeboard is met. Non-residential and mixed-use buildings face the same one-foot freeboard, but Section 6-307(B)(3) lets them dry-floodproof instead of elevating, provided a registered engineer or architect certifies the building is watertight below the BFE-plus-one-foot line and no floor below that line is used for human or animal habitation, food storage, or food preparation.

2-percent annual chance flood elevation. Mechanical, electrical, heating, and plumbing equipment must likewise sit at or above the base flood elevation plus one foot under Section 6-306(E), and any fully enclosed space left below that line can only be used for parking, building access, or storage, built from flood damage-resistant materials, with vents sized to at least one square inch per square foot of enclosed area.