Collierville, TN Environmental Rules: Flood Elevation Requirements (2026)

Section 151.100(B)(1) of the Collierville Code of Ordinances governs areas of special flood hazard where base flood elevation data have been provided, including A, A1-30, AE, AO, AH and A99 zones. For residential construction, new construction or substantial improvement to any residential building (or manufactured home) must have the lowest floor, including basement, elevated no lower than one foot above the base flood elevation. Commercial, industrial and other nonresidential buildings follow the same one foot standard.

Nonresidential buildings in A zones have an alternative. They can be flood-proofed in lieu of being elevated, provided all areas of the building below the required elevation are water tight with walls substantially impermeable to the passage of water and built with structural components able to resist hydrostatic and hydrodynamic loads and the effects of buoyancy. A registered professional engineer or architect must certify the standards are met and provide the certification to the Development Director under § 151.099(B)(2).

Manufactured homes follow the same height: the lowest floor must be elevated no lower than one foot above the level of the base flood elevation on a permanent foundation. Elevated buildings with fully enclosed areas below the base flood elevation must be designed to preclude finished living space and allow floodwaters in and out. The openings test is a minimum of two openings with a total net area of not less than one square inch for every square foot of enclosed area, with the bottom of all openings no higher than one foot above grade.

Shallow flooding zones use a different reference. Under § 151.100(D), where base flood depths run one to three feet, the lowest floor must be elevated to the depth number on the Flood Insurance Rate Map, in feet, above the highest adjacent grade, and if no depth number is specified, at least two feet above the highest adjacent grade.

Elevation is checked twice. The application lists the proposed lowest floor elevation relative to mean sea level, and after the lowest floor is placed the permit holder submits an as-built certification under § 151.099(B)(2). The Board of Zoning Appeals handles variances under § 151.101.