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

Section 3.12.072 of the Sherman Code sets the elevation standards in all areas of special flood hazard in the City of Sherman, Texas where base flood elevation data has been provided, whether from the FEMA study adopted in section 3.12.007, from data the floodplain administrator obtains under section 3.12.042(8), or under section 3.12.074(c). The code builds in freeboard: the lowest floor, including a basement, must sit two feet above the base flood elevation for residential construction. A registered professional engineer, architect or land surveyor must certify to the floodplain administrator that the standards proposed in section 3.12.043(b)(1) through (4) are satisfied.

Nonresidential buildings get a choice. New construction and substantial improvements of any commercial, industrial or other nonresidential structure either elevate the lowest floor to at least two feet above the base flood level or are designed, with attendant utility and sanitary facilities, to be watertight below the base flood level, with walls substantially impermeable to water and structure able to resist hydrostatic and hydrodynamic loads and buoyancy. A registered professional engineer or architect develops or reviews that design, certifies it, and the floodplain administrator keeps a record showing the specific elevation to which the structure is floodproofed.

Other elevation rules sit in the same section. Fully enclosed areas below the lowest floor, usable only for parking, building access or storage, need at least two openings on separate walls with a total net area of not less than one square inch per square foot of enclosed area, and the bottom of every opening can be no higher than one foot above grade. Manufactured homes in zones A1-30, AH and AE must have the lowest floor at least three feet above base flood elevation, or the chassis on piers no less than 36 inches above grade. Fill brought into the 1% annual chance floodplain is unlawful except sand for an approved foundation. Substantial improvement means work costing 50 percent or more of the structure's market value, and a variance that allows a lower floor below base flood elevation requires written notice that flood insurance will cost more.