Ch. 16.05 Art. V Provisions for Flood Hazard Reduction

Article V. Provisions for Flood Hazard Reduction

16.05.200 Standards of construction.

In all special flood hazard areas, the following standards are required:

1. All new construction and substantial improvements shall be anchored to prevent flotation, collapse, or lateral movement of the structure resulting from hydrodynamic and hydrostatic loads including the effects of buoyancy; and

2. All manufactured homes shall meet the anchoring standards of MCC 16.05.240(B).

1. All new construction and substantial improvements shall be constructed with materials and utility equipment resistant to flood damage;

2. All new construction and substantial improvements shall be constructed using methods and practices that minimize flood damage; and

3. Within Zones AH or AO, adequate drainage paths shall be constructed around structures on slopes to guide floodwaters around and away from proposed structures.

1. Residential Construction. Residential construction, new, or substantial improvement, shall have the lowest floor, including basement, elevated to or above the regulatory flood elevation.

a. In a Zone AO, the base flood elevation is determined from the FIRM panel. If unspecified, the required elevation is at minimum two feet above highest adjacent grade.

b. In a Zone A where the base flood elevation has not been determined, the base flood elevation is determined locally by the criteria set out in MCC 16.05.180(C).

c. In Zones AE and AH, the base flood elevation is determined from the FIS and/or FIRM.

d. A garage attached to a residential structure, constructed with the garage floor slab below the regulatory flood elevation, must be designed to allow for the automatic entry and exit of flood waters and must be used solely for parking, access and/or storage. See subsection (C)(5)(a) or (b) of this section.

2. Nonresidential Construction (Commercial Construction or Industrial Construction). Nonresidential construction, new, or substantial improvement, shall have the lowest floor either elevated to conform with subsection (C)(1)(a), (b), or (c) of this section as appropriate, or, together with attendant utility and sanitary facilities:

a. Be floodproofed below the elevation recommended under subsection (C)(1)(a), (b), or (c) of this section as appropriate so that the structure is watertight with walls substantially impermeable to the passage of water; and

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

Upon completion of the structure, certification by a registered professional engineer or surveyor that the elevation requirements of the lowest floor, including basement, of this section have been satisfied shall be provided to the floodplain administrator for verification; or certification by a registered professional engineer or architect that the floodproofing standards of this section are satisfied shall be provided to the floodplain administrator for verification.

3. Manufactured Homes. Manufactured homes shall meet the standards in MCC 16.05.240.

4. Accessory Structures (Detached Garages and Storage Structures). Accessory structures up to 600 square feet, used solely for parking of vehicles or storage, may be constructed such that the floor is below the regulatory flood elevation, provided the structure is designed and constructed in accordance with the following requirements:

a. Use of the accessory structure must be limited to parking of vehicles or storage;

b. The portions of the accessory structure located below the regulatory flood elevation must be built using flood resistant materials;

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

d. Any machinery or equipment servicing the accessory structure must be elevated or floodproofed to or above the regulatory flood elevation;

e. The accessory structure must comply with floodway encroachment provisions in MCC 16.05.260; and

f. The accessory structure must be designed to allow for the automatic entry and exit of flood waters in accordance with subsection (C)(5)(a) or (b) of this section.

Detached garages, storage structures, and other accessory structures not meeting the above standards must be constructed in accordance with all applicable standards in subsection (C)(1)(a), (b), or (c) of this section as appropriate.

Upon completion of the structure, certification by a registered professional engineer or surveyor that the requirements of this section have been satisfied shall be provided to the floodplain administrator for verification.

5. Flood Openings. All new construction and substantial improvement with fully enclosed areas below the lowest floor (excluding basements) that are usable solely for parking of vehicles, building access, or storage, and which are subject to flooding, shall be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for the automatic entry and exit of floodwater. Designs for meeting this requirement must meet or exceed the following criteria:

a. For nonengineered openings:

i. Have a minimum of two openings, on different sides of each enclosed area, having a total net area of not less than one square inch for every square foot of enclosed area subject to flooding;

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

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

b. For engineered openings:

i. Engineered openings (or covers and devices) that are specifically designed and certified by a registered engineer or architect as meeting the required performance and design requirements.

ii. Engineered openings (or covers and devices) for which an evaluation report has been issued by the International Code Council (ICC) Evaluation Service, Inc. (ICC-ES), a subsidiary of the International Code Council, Inc.

6. Machinery and Service Equipment. All new construction, substantial improvement, and other proposed new development shall be constructed with electrical, heating, ventilation, plumbing, air conditioning equipment, and other service facilities that are designed and/or located so as to prevent water from entering or accumulating within the components during conditions of flooding. [Ord. 23-29 § 2 (5.1).]