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elevate a structure's lowest floor above the regulatory flood protection elevation. These alternative methods may include the use of stilts, pilings, parallel walls and the like, or above-grade, enclosed areas such as crawl spaces or tuck-under garages. The base or . floor of an enclosed area shall be considered above-grade and not a structure's basement or lowest floor if: the enclosed area is above grade on at least 1 side of the structure; the enclosed area is designed to flood internally and is constructed with flood-resistant materials;. and the enclosed area is Used solely for parking of vehicles, building access or storage. The above-noted alternative elevation methods are subject to the following additional standards: (a) Design and certification. The structure's design and as-built condition must be certified by a registered professional engineer or architect as being in compliance with the general design standards of the Minnesota Building Code and, specifically, that all electrical, heating, ventilation, plumbing and air conditioning equipment and other service facilities must be at or above the regulatory flood protection elevation or be. designed to prevent floodwater from entering or accumulating within these components during times of flooding. (b) Specific standards for above-grade, enclosed areas. Above-grade, fully enclosed areas such as crawl spaces or tuck-under garages must be designed to flood internally, and the design plans must stipulate: 1. The minimum area of openings in the walls where internal flooding is to be used as a flood-proofing technique. When openings are placed in a structure's walls to provide for entry of floodwaters to equalize pressures, the bottom of all openings shall be no higher than 1 foot above grade. Openings may be equipped with screens, louvers, valves or other coverings or devices; provided, that they permit the automatic entry and exit of floodwaters; and 2. That the enclosed area will be designed of flood-resistant materials in accordance with the FP-3 or FP-4 classifications in the Minnesota Building Code and shall be used solely for building access, parking of vehicles or storage. (2) Basements, as defined in this chapter, shall be subject to the following: (a) Residential basement construction shall not be allowed below ~e regulatory flood protection elevation; and (b) Nonresidential basements may be allowed below the regulatory flood protection elevation; provided, that the basement is structurally dry flood-proofed in accordance with this chapter. (3) All areas of nonresidential structures, including basements, to be placed below the regulatory flood protection elevation shall be flood-proofed in accordance with the structurally dry flood-proofing classifications in the Minnesota Building Code. Structurally dry flood-proofing must meet the FP-l or FP-2 flood-proofing classification in the Minnesota Building Code and this shall require making the structure watertight witQ the walls substantially ~permeable to the passage. of water and with structural components having the capability of buoyancy. Structures flood-proofed to the FP-3 or FP-4 classification shall not be permitted. (4) When at any 1 time more than 1,000 cubic yards offill or other similar material is located on a parcel for activities such as on-site storage, landscaping, sand and gravel operations, landfills, roads, dredge spoil disposal or construction of flood control 9