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,- e e e 3, The bottom of each opening can be no more than 1 foot above the adjacent grade, 4. Any louvers, screens, or other opening covers must not block or impede the automatic flow of floodwaters into and out of the enclosed area. Types of Buildings Affected In all cases, any enclosed area below the BFE is subject to flood forces and must be equipped with exterior wall openings in accordance with the NFIP regulations, either at the time of initial construction or, if the building is being substantially improved, at the time of improvement. The only exception to this requirement is floodproofed non-residential buildings that are engineered and meet stringent watertight construction requirements. For further information on this topic, refer to Technical Bulletin 3, "Non-Residential Floodproofing - Requirements and Certifica- tion." Buildings Elevated on Solid Foundation Walls When a building is elevated on solid foundation walls, an enclosed area is often created below the lowest floor, All foundation enclosures below the BFE must have openings that meet NFIP criteria. Figure 1 shows an example of a properly placed foundation opening, As discussed previously, screens, louvers, or other covers that allow floodwaters to flow freely into the enclosed area may be placed over the openings to keep out vermin and weather. Care must be taken when placing fill dirt around the outside of the foundation. The resulting enclosed area may be considered a basement under the NFIP. A basement is defined as any area of a building having a floor (finished or unfinished) that is subgrade (below grade) on all sides. The NFIP regulations do not permit a residential building in an SFHA to have a BFE I lloItomof 12' Mox;mum -1 ~-Opening Height Above Grode ~_ ~ I I L F:~~~rade Block Foundation-t---l LJ I I rJ_L., I I L J Figure 1, Opening lor Solid Foundation Wall basement whose lowest floor (including basement) is below the BFE. To meet the NFIP requirements, fill placed around foundation walls must be graded so that the grade inside the enclosed area is equal to or higher than the adjacent grade outside the building on at least one side of the building (as illustrated in Figure 2). If the grade inside the foundation walls is above the BFE, openings are not required. / Adjocent Grode BFE Figure 2, Compliant Grading lor a Walkout Basement 3