Richardson, TX Environmental Rules: Flood Zones (2026)

The floodplain chapter (ch. 9) applies to all areas of special flood hazard in the city and is administered by the city engineer under Section 9-42, who issues development permits under Section 9-43 after weighing danger to life and property, flood velocity and access for emergency vehicles. Section 9-67(a) sets the residential elevation standard: two feet above base flood elevation for the lowest floor, verified by a FEMA elevation certificate from a registered engineer or surveyor. Nonresidential buildings may floodproof instead under 9-67(b), with a registered engineer certifying the design and the floodplain administrator keeping the certified elevation on file.

Manufactured homes placed in zones A1-30, AH and AE must sit on a permanent foundation two feet above base flood elevation and be anchored against flotation; none may be placed in a floodway at all under 9-67(c). Enclosed areas below the lowest floor used only for parking, access or storage must carry at least two flood vents on separate walls, sized to one square inch per square foot of enclosed area and no higher than one foot above grade, under 9-67(d). Section 9-67(e) bars any new encroachment, fill or improvement within the adopted regulatory floodway unless hydrologic and hydraulic analysis shows no increase in flood levels.

Recreational vehicles are exempt from the permit process if they stay fewer than 180 consecutive days or remain licensed and ready for highway use. Detached accessory structures used only for parking or storage may sit at grade if limited to a one-story, two-car garage of no more than 600 square feet with compliant flood openings. Property owners seeking relief apply for a variance under Section 9-45, heard by the city council, which may attach conditions and must find the variance is the minimum necessary given the flood hazard; anyone aggrieved by that decision may appeal to the courts.