Mississippi Administrative Code › Title 33 - Public Health - Local Governments And Rural Water Systems Improvements Board › Part 208 - Flood Damage Prevention Regulation › Chapter 5 - Provisions for Flood Hazard Reduction › Rule 33-208-5.2 - Specific Standards for Riverine Zones

Current through June 25, 2024
In all areas of special flood hazard designated on the
				  community's FIRM, where base flood elevation data have been provided (excluding
				  CHHA and Coastal AE Zone), as set forth in Part 208, Rule 3.1 & 3.2, the
				  following provisions, in addition to the standards of Part 208, Rule 5.1, are
				  required:
(1)
Residential
				Construction
. New construction and substantial improvement of any
				residential building (including manufactured home) shall have the lowest floor,
				including basement, elevated to no lower than 18 inches the base flood
				elevation. Should solid foundation perimeter walls be used to elevate a
				structure, flood openings sufficient to automatically equalize hydrostatic
				flood forces on exterior walls of enclosures that are subject to flooding,
				shall be provided in accordance with standards of Part 208, Rule 5.1. New
				development proposals will be designed, to the maximum extent practicable, so
				residential building sites, walkways, driveways, and roadways are located at
				natural grade with elevation not less than the base flood elevation and with
				evacuation routes leading directly out of the special flood hazard
				area.
(2)
Non-Residential Construction
. New construction and
				substantial improvement of any commercial, industrial, or non-residential
				building (including manufactured building) shall have the lowest floor,
				including basement, elevated to no lower than 18 inches the base flood
				elevation. Buildings located in all A Zones may, together with attendant
				utility and sanitary facilities, be floodproofed in lieu of being elevated
				provided that all areas of the building below the base flood elevation (plus a
				minimum of 18 inches of freeboard are water tight with walls substantially
				impermeable to the passage of water, and use structural components having the
				capability of resisting hydrostatic and hydrodynamic loads and the effect of
				buoyancy. Dry floodproofing is allowed only where flood velocities are less
				than or equal to five feet per second. A registered professional engineer or
				architect shall certify that the standards of this subsection are satisfied. A
				Flood Emergency Operation Plan and an Inspection and Maintenance Plan must be
				provided by the design professional for the building. Such certification shall
				be provided to the Floodplain Administrator. New development proposals will be
				designed, to the maximum extent practicable, so non-residential building sites,
				walkways, driveways, and roadways are located at natural grade with elevation
				not less than the base flood elevation and with evacuation routes leading
				directly out of the special flood hazard area.
(3) In special flood hazard areas with base
				flood elevations (AE Zones) but without floodways, no encroachments, including
				fill material or structures, shall be permitted unless certification by a
				registered professional engineer is provided demonstrating that the cumulative
				effect of the proposed development, when combined with all other existing and
				anticipated development, will not increase the water surface elevation of the
				base flood more than one foot at any point within the community. The
				engineering certification must be supported by technical data that conforms to
				standard hydraulic engineering principles.
(4) Enclosures. New construction and
				substantial improvements that include fully enclosed areas formed by foundation
				and other exterior walls below the lowest floor shall be designed to preclude
				finished living space and designed to allow for the entry and exit of
				floodwaters to automatically equalize hydrostatic flood forces on exterior
				walls. Enclosed areas including crawl spaces, shall be used solely for parking
				of vehicles, building access, and storage.
a.) Designs for complying with this
				requirement must either be certified by a professional engineer or architect or
				meet or exceed the following criteria:
(i)
				Provide a minimum of two openings, on different sides of each enclosed area; if
				a structure has more than one enclosed area below the base flood elevation,
				each shall have openings on exterior walls;
(ii) The total net area of all openings shall
				be at least one square inch for each square foot of enclosed area, or the
				openings shall be designed and the construction documents shall include a
				statement that the design and installation will provide for equalization of
				hydrostatic flood forces on exterior walls by allowing for the automatic entry
				and exit of floodwaters;
(iii) The
				bottom of all openings shall be no higher than one foot above interior grade
				(which must be equal to in elevation or higher than the exterior
				grade);
(iv) Openings shall allow
				the passage of a three inch sphere.
(v) Openings may be equipped with screens,
				louvers, valves or other coverings or devices provided they permit the
				automatic flow of floodwaters in both directions and automatically equalize
				hydrostatic flood loads on exterior walls, and;