14.34.130 Specific standards for pre-existing use exemptions

14.34.130 Specific standards for pre-existing use exemptions.

In all areas of special flood hazards where base flood elevation data has been provided or can be reasonably obtained as set forth in LMC 14.34.030 or 14.34.100(B), the following provisions are required:

1. Substantial improvement of any pre-existing residential structure shall have the lowest floor, including basement, elevated one foot or more above the base flood elevation (BFE) and shall not be permitted in the floodway (see LMC 14.34.140(B)). Mechanical equipment and utilities shall be waterproof or elevated at least one foot above the BFE.

a. The substantial improvement will not increase the footprint of the structure.

2. Fully enclosed areas below the lowest floor that are subject to flooding are prohibited, or shall be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for the entry and exit of floodwaters. Designs for meeting this requirement must either be certified by a registered professional engineer or architect or must meet or exceed the following minimum criteria:

a. 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 shall be provided.

b. The bottom of all openings shall be no higher than one foot above grade.

c. Openings may be equipped with screens, louvers, or other coverings or devices; provided, that they permit the automatic entry and exit of floodwaters.

d. A garage attached to a residential structure, constructed with the garage floor slab below the BFE, must be designed to allow for the automatic entry and exit of floodwaters.

Alternatively, a registered engineer or architect may design and certify engineered openings.

3. Substantial improvements are only allowed as permitted by listed exemptions in LMC 14.34.082. Where a pre-existing structure is involved, maintenance or improvements shall not increase the footprint of the structure (LMC 14.34.082).

4. New construction and substantial improvement of any residential structure in an unnumbered A zone for which a BFE is not available and cannot be reasonably obtained shall be reasonably safe from flooding, but in all cases the lowest floor shall be at least two feet above the highest adjacent grade.

5. New construction and substantial improvement of any residential structure in a V, V1-30, or VE zone shall meet the requirements in LMC 14.34.135.

B. Nonresidential Construction. Substantial improvement of any pre-existing commercial, industrial or other nonresidential structure and new structures permitted as an exemption identified in LMC 14.34.082 and 14.34.084, shall meet the requirements of subsection (B)(1) or (B)(2) of this section.

1. Substantial improvement of any pre-existing commercial, industrial or other nonresidential structure and new structures permitted as an exemption identified in LMC 14.34.082 and 14.34.084 shall meet the requirements:

a. In AE and A1-30 zones or other A zoned areas where the BFE has been determined or can be reasonably obtained:

Substantial improvement of any commercial, industrial, or other nonresidential structure shall have the lowest floor, including basement, elevated one foot or more above the BFE, or elevated as required by ASCE 24, whichever is greater. Mechanical equipment and utilities shall be waterproofed or elevated least one foot above the BFE, or as required by ASCE 24, whichever is greater.

b. If located in an unnumbered A zone for which a BFE is not available and cannot be reasonably obtained, the structure shall be reasonably safe from flooding, but in all cases the lowest floor shall be at least two feet above the highest adjacent grade.

c. If located in a V, V1-30, or VE zone, the structure shall meet the requirements in LMC 14.34.135.

d. Fully enclosed areas below the lowest floor that are subject to flooding are prohibited, or shall meet the requirements of LMC 14.34.130(A)(2).

2. If the requirements of subsection (B)(1) of this section are not met, then substantial improvement of any pre-existing commercial, industrial or other nonresidential structure shall meet all of the following requirements:

a. Be dry floodproofed so that below one foot above the base flood level the structure is watertight with walls substantially impermeable to the passage of water or dry floodproofed to the elevation required by ASCE 24, whichever is greater;

b. Have structural components capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy;

c. Be certified by a registered professional engineer or architect that the design and methods of construction are in accordance with accepted standards of practice for meeting provisions of this subsection based on their development and/or review of the structural design, specifications and plans;

d. Nonresidential structures that are elevated but not floodproofed must meet the same standards for space below the lowest floor as described in subsection (A)(2) of this section;

e. The footprint of a pre-existing structure shall not be increased (LMC 14.34.082);

f. Applicants floodproofing nonresidential buildings shall be notified that flood insurance premiums will be based on rates that are one foot below the floodproofed level (e.g., a building floodproofed to one foot above the base flood level will be rated at the base flood level).

Applicants who are floodproofing nonresidential buildings shall be notified that flood insurance premiums will be based on rates that are one foot below the floodproofed level (e.g., a building floodproofed to the base flood level will be rated as one foot below). Floodproofing the building an additional foot will reduce insurance premiums.

1. All manufactured homes are prohibited in the area of special flood hazard.

1. Be on the site for fewer than one hundred eighty days; or

2. Recreational vehicles placed on sites in areas of special flood hazard shall be fully licensed and ready for highway use, on wheels or jacking systems, attached to the site by only quick disconnect type utilities and security devices and have no permanently attached additions; or

3. Meet the requirements of subsection C of this section.

E. Enclosed Area Below the Lowest Floor. If buildings or manufactured homes are constructed or substantially improved with fully enclosed areas below the lowest floor, the areas shall be used solely for parking of vehicles, building access, or storage.

1. Detached accessory structures used solely for parking of vehicles or limited storage may be constructed such that the floor is below the BFE, provided the structure is designed and constructed in accordance with the following requirements:

a. In special flood hazard areas other than coastal high hazard areas (Zones A, AE, AH, AO, and A1-30), the structure is not larger than a one-story two-car garage;

b. In coastal high hazard areas (Zones V, VE, V1 30, and VO), the structure is not larger than one hundred square feet in area;

c. The portions of the structure located below the BFE must be built using flood resistant materials;

d. The structure must be adequately anchored to prevent flotation, collapse, and lateral movement;

e. Any machinery or equipment servicing the structure must be elevated or floodproofed to or above the BFE;

f. The structure must comply with floodway encroachment provisions in LMC 14.34.140(A);

g. The structure must be designed to allow for the automatic entry and exit of flood waters in accordance with LMC 14.34.130(A)(2);

h. The structure shall have low damage potential;

i. If the structure is converted to another use, it must be brought into full compliance with the standards governing such use; and

j. The structure shall not be used for human habitation. (Ord. 1654 §6, 2023; Ord. 1505 §39, 2017; Ord. 1398 §10, 2012; Ord. 1375 §26, 2011; Ord. 1265 §5, 2006; Ord. 861 §2 (part), 1989).