Washington, DC Environmental Rules: Flood Elevation Requirements (2026)

C. Code § 6-501(a) requires the Mayor to review every building permit application for new construction or substantial improvement to determine whether the site will be reasonably safe from flooding. If the site sits in a location with flood hazard, the project, including prefabricated homes, must be designed or modified and anchored to prevent flotation, collapse, or lateral movement; must use construction materials and utility equipment resistant to flood damage; and must use construction methods and practices that minimize flood damage. Under § 6-501(b)(1), the Mayor may issue rules designating flood hazard areas and requiring flood insurance as a condition of occupancy for the life of a new or substantially improved building located in one.

A flood hazard area is defined in § 6-501(b)(2)(A) as a special flood hazard area or other flood-hazard area on the then-current FEMA flood insurance rate map for the District, or an area the Mayor designates by rule. A "substantially improved building" under § 6-501(b)(2)(B) is one that has undergone repair, alteration, addition, or improvement costing 50% or more of the building's market value before the work started, a threshold that pulls renovation projects into the insurance mandate even without new construction. C. C. Law 24-151 in August 2022, also directs the Mayor to review subdivision and drainage plans under the related § 6-502 to keep utilities and drainage clear of flood hazards.