Rowlett, TX Environmental Rules: Flood Elevation Requirements (2026)

Section 82-48 sets the specific elevation standards that apply once base flood elevation data has been provided under §§ 82-37, 82-44(8) or 82-49(3). For residential construction, new buildings and substantial improvements must have the lowest floor, including any basement, elevated to two feet above the base flood elevation, and a registered professional engineer, architect or land surveyor must certify that standard to the floodplain administrator under § 82-45(a). Nonresidential structures, commercial, industrial or otherwise, have two compliance paths: elevate the lowest floor two feet above base flood level, or design the structure watertight below that level with walls substantially impermeable to water and components able to resist hydrostatic and hydrodynamic loads; an engineer or architect must develop or review the design and certify it, and the administrator keeps a record of the certified floodproofed elevation.

Fully enclosed areas below the lowest floor used only for parking, building access or storage must be engineered to automatically equalize hydrostatic flood forces, or meet minimum criteria: at least two openings on separate walls totaling one square inch of net area per square foot of enclosed area, with the bottom of every opening no higher than one foot above grade. Manufactured homes placed in Zone A must be elevated and anchored against flotation, collapse or lateral movement using methods such as frame ties to ground anchors; homes placed or substantially improved in Zones A1-30, AH and AE outside an existing manufactured home park, in a new or expanded park, or in a park where a home was substantially damaged by flood, must sit on a permanent foundation with the lowest floor two feet above base flood elevation.

Recreational vehicles in those same zones must either stay fewer than 180 consecutive days, remain fully licensed and highway-ready, or meet the same permit, elevation and anchoring standards as manufactured homes.