Fully-enclosed areas below base flood elevation may be allowed by conditional variance only. New construction or substantial improvements of buildings that include full-enclosed areas formed by foundation and other exterior walls below the base flood elevation shall be designed to preclude finished living space and designed to allow for the automatic entry and exit of floodwaters to equalize hydrostatic flood forces on exterior walls.
(A) Designs for complying with this requirement must either be certified by a professional engineer or architect or meet the following minimum criteria:
(1) Provide a minimum of two openings having a total net area of not less than one square inch for every square foot of enclosed area subject to flooding;
(2) The bottom of all openings shall be no higher than one foot above grade; and
(3) Openings may be equipped with screens, louvers, valves or other coverings or devices provided they permit the automatic flow of floodwaters in both directions. Non-supporting breakaway wall, lattice work or mesh screening may be allowed below the base flood elevation provided it is not part of the structural support of the building and is designed so as to breakaway, under abnormally high tides or wave action, without damage to the structural integrity of the building on which it is to be used and provided the following design specifications are met:
(a) Design safe loading resistance of each wall shall not be less than ten nor more than 20 pounds per square foot; or
(b) If more than 20 pounds per square foot, a registered professional engineer or architect shall certify that the design wall collapse would result from a water load less than that which would occur during the base flood event, and the elevated portion of the building and supporting foundation system shall not be subject to collapse, displacement or other structural damage due to the effect of wind and water loads acting simultaneously on all building components during the base flood event. Maximum wind and water loading values to be used in this determination shall each have 1% chance of being equaled or exceeded in any given year (100-year mean recurrence interval).
(B) Electrical, plumbing and other utility connections are prohibited below the base flood elevations.
(C) Access to the enclosed area shall be the minimum necessary to allow for parking of vehicles (garage door) or limited storage of maintenance equipment used in connection with the premises (standard exterior door) or entry to the living area (stairway or elevator).
(Ord. passed 4-11-1991; Ord. passed 5-10-2010)