(a) The building must be designed and adequately anchored to resist flotation, collapse, and lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy. Hydrostatic loads and the effects of buoyancy can usually be addressed through the required openings discussed in subsection (1)(b) of this section. Crawlspace construction is not recommended in areas where flood velocities exceed five feet per second, unless the design is reviewed and certified by a registered architect or professional engineer.

(b) The crawlspace is an enclosed area below the base flood elevation and, as such, must have openings that equalize hydrostatic pressures by allowing for the automatic entry and exit of floodwaters. The bottom of each flood vent opening can be no more than one foot above the lowest adjacent interior and exterior grade. Crawlspace construction is not permitted in FEMA coastal high hazard area designated V zones. Open pile or column foundations that withstand storm surge and wave forces are required in V zones.

(c) Portions of the building below the base flood elevation must be constructed with materials resistant to flood damage. This includes not only the foundation walls of the crawlspace used to elevate the building, but also any joists, insulation, or other materials that extend below the base flood elevations. The recommended construction practice is to elevate the bottom of joists and all insulation above base flood elevation. Insulation is not a flood-resistant material. When insulation becomes saturated with floodwater, the additional weight often pulls it away from the joists and flooring. Ductwork or other utility systems located below the insulation may also pull away from their supports.

(d) Any building utility systems including ductwork within the crawlspace must be elevated above base flood elevation or designed so that floodwaters cannot enter or accumulate within the system components during flood conditions. Ductwork must either be placed one foot above the base flood elevation or sealed from floodwaters. (Added by Amended Ord. 05-068, Sept. 7, 2005, Eff date Sept. 24, 2005; Amended by Amended Ord. 07-005, Feb. 21, 2007, Eff date Mar. 4, 2007; Amended by Ord. 20-076, Nov. 4, 2020, Eff date Nov. 27, 2020).