Layton, UT Environmental Rules: Flood Elevation Requirements (2026)

150(5)(a)(i) governs freeboard in areas where base flood elevation data has been established: "Substantial improvement of any residential structure within the special flood hazard area indicated on the FIRM mapping shall have the lowest floor, including basement, elevated one foot (1') above the base flood elevation," and a registered professional engineer, architect, or land surveyor must certify to the City Engineer that this standard is met. The same subsection goes further than the one-foot freeboard by stating flatly that new construction of any residential structure is not allowed within the special flood hazard area at all, reserving that ground for substantial improvements only.

150(5)(b) get an alternative path: the lowest floor can be elevated to or above base flood elevation, or the building can instead be floodproofed watertight below the base flood level with walls substantially impermeable to water and structural components able to resist hydrostatic and hydrodynamic loads, again certified by a registered engineer or architect. 150(6) use a different measure tied to the depth number shown on the FIRM, elevating the lowest floor above the highest adjacent grade rather than to a fixed base flood elevation.

150(5)(d)-(e), including a floor elevated to or above base flood elevation or chassis supported by reinforced piers at least 36 inches above grade. These flood hazard reduction standards were most recently amended by Ordinance 22-19 on August 4, 2022.