Portland, ME Environmental Rules: Flood Elevation Requirements (2026)

Land Use Code Section 12.4.5(H) sets the elevation standard for residential construction in Portland's mapped flood zones. New construction or substantial improvement of a residential structure in Zones AE, AO or AH must have its lowest floor, including any basement, elevated to at least two feet above the base flood elevation, a two-foot freeboard margin above the minimum federal standard. In Zones AO and AH, the structure must also have adequate drainage paths on sloped sites to steer floodwater away from the building. Section 12.4.5(H)(4) applies the same two-foot standard in Zone A, where the base flood elevation is not otherwise mapped: the elevation is calculated from data obtained under Sections 12.4.2(J)(1)(b)(i), 12.4.4(C) or 12.4.4(B)(4) where such data exists, or, in its absence, from a point two feet above the highest ground elevation adjacent to the structure.

Zones VE and Coastal AE, the coastal high-hazard zones exposed to wave action, are carved out of this residential standard and instead must meet the separate elevation and breakaway-wall requirements of Section 12.4.5(R). These elevation figures are certified using the National Geodetic Vertical Datum, North American Vertical Datum, or a locally established datum for Zone A, and are verified through the Flood Hazard Development Permit application required under Section 12.4.1.