St. Martin Parish, LA Environmental Rules: Flood Elevation Requirements (2026)

The freeboard rule in Sec. 14-66(b) applies in all areas of special flood hazard to all new construction and substantial improvements. The minimum lowest floor elevation is one foot above the higher of three measurements: the base flood elevation from the latest FIRM issued by FEMA, the centerline of the nearest street across from or adjacent to the structure, or the highest recorded historical or modeled (100-year) inundation level. All mechanical equipment must meet the same minimum. If the calculation produces an unreasonable elevation, a waiver can be requested, and a licensed land surveyor or engineer certifies the result on the freeboard elevation form, which is available at the St. Martin Parish Government building, 400 Port Street, St. Martinville.

Sec. 14-67 carries the rule into each building type. Residential construction must have the lowest floor, including a basement, elevated to freeboard, attached garages and utilities must meet the same requirement, and a registered professional engineer, architect or land surveyor certifies compliance to the floodplain administrator. Nonresidential buildings must elevate the lowest floor, including basement and garage or carport, to freeboard, or be designed watertight below the base flood level with engineer or architect certification. Manufactured homes in an existing park or subdivision are measured from the bottom of the lowest longitudinal frame beam. Fully enclosed areas below the lowest floor need at least two openings on separate walls with a total net area of not less than one square inch for every square foot of enclosed area, the bottoms no higher than one foot above grade.

Accessory structures get a narrow alternative. Under Sec. 14-67(4), an accessory structure used only for parking or limited storage and no larger than 1,500 square feet can be wet floodproofed instead of elevated, with electrical service of 60 amps or less at least one foot above the BFE; anything larger must be elevated one foot above the BFE. In AO and AH shallow flooding zones, Sec. 14-69 requires the lowest floor at least one foot above the base flood elevation or the highest adjacent grade at least as high as the FIRM depth number, and at least two feet if no depth number is specified. The plat statement under Sec. 14-68(h) excludes garages, carports and porches from the one foot rule and places them at a minimum of six inches above the base flood elevation.