Harrisburg, PA Environmental Rules: Flood Elevation Requirements (2026)

Harrisburg Codified Ordinances § 7-315.3, the definitions section of the Floodplain Overlay District chapter, fixes the freeboard rule for the City of Harrisburg. The base flood elevation (BFE) is the elevation shown on the Flood Insurance Rate Map for Zones AE, AH, and A1-30 that indicates the water surface elevation resulting from a flood with a one-percent or greater chance of being equaled or exceeded in any given year. The regulatory flood elevation is that BFE plus a freeboard safety factor of 1 1/2 feet.

Residential: under § 7-315.23(B), in AE, A1-30, and AH Zones any new construction or substantial improvement of a residential structure must have the lowest floor, including the basement, elevated up to or above the regulatory flood elevation. In AO Zones the lowest floor must be at or above the highest adjacent grade at least as high as the depth number specified on the FIRM. In A Zones with no BFE on the FIRM, the lowest floor must still reach the regulatory flood elevation, determined under § 7-315.9(C)(2).

Nonresidential: under § 7-315.23(C), a nonresidential structure must be elevated to or above the regulatory flood elevation or be designed so the enclosed space below it is watertight with walls substantially impermeable to water, and the plans must carry a statement certified by a registered professional engineer or architect.

Substantial improvement: § 7-315.3 defines it as an improvement costing 50% or more of the structure's market value, and § 7-315.29 requires work of that size to meet the chapter in full.

Other elevation figures printed in the chapter: electrical distribution panels must be at least three feet above the base flood elevation (§ 7-315.24(K)(1)); the finished elevation of new streets can be no more than one foot below the regulatory flood elevation (§ 7-315.24(E)); water heaters, furnaces, and air-conditioning units cannot sit below the regulatory flood elevation (§ 7-315.24(L)); and a structure that stores or produces listed dangerous materials must be elevated or built to stay completely dry up to at least 1 1/2 feet above base flood elevation (§ 7-315.25(C)(1)). Accessory structures of no more than 100 square feet need not be elevated if they meet the conditions in § 7-315.23(E).