§ 18-78. Standards of construction.

For all construction, and as additions but not reductions of other standards or requirements of laws, the following standards are required:

(1)

Anchoring.

a.

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

b.

All manufactured homes shall meet the anchoring standards of section 18-82.

(2)

Construction materials and methods.

a.

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

b.

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

c.

All new construction and substantial improvements and other proposed new development shall be constructed with electrical, heating, ventilation, plumbing and 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; and

d.

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

(3)

Elevation and floodproofing. New construction, subsequent improvements, and:

a.

Substantial improvements of any structure shall have the lowest floor, including basement, elevated to or above the regulatory flood elevation. Nonresidential structures may meet the standards in section 5, article 1(C)6.

b.

New construction, subsequent improvements, and substantial improvements of any structure in Zone AO shall have the lowest floor higher than the highest adjacent grade by at least one foot higher than the depth number on the flood insurance rate map, or at least two feet if no depth number is specified. Nonresidential structures may meet the standards in subsection (3)e and f of this section. Upon the completion of the structure or other modifications or additions thereto, the elevation of the lowest floor, including basement, shall be certified by a state registered professional engineer or surveyor and the original sealed and signed copy of the elevation certificate shall be provided to the floodplain administrator, together with field notes and data.

c.

New construction, subsequent improvements, and substantial improvements of any structure in an A Zone where a base flood elevation has not been determined shall have the lowest floor elevated to or above the regulatory flood elevation or be elevated in accordance with the criteria developed by the director of the ADWR. Upon the completion of the structure or other modifications or additions thereto, the elevation of the lowest floor, including basement, shall be certified by a state registered professional engineer or surveyor and the original sealed and signed copy of the elevation certificate shall be provided to the floodplain administrator, together with field notes and data.

d.

New construction, subsequent improvements, and substantial improvements of any structure in Zones AE or AH, shall have the lowest floor elevated to or above the regulatory flood elevation. Upon the completion of the structure or other modifications or additions thereto, the elevation of the lowest floor, including basement, shall be certified by a state registered professional engineer or surveyor and the original sealed and signed copy of the elevation certificate shall be provided to the floodplain administrator, together with field notes and data.

e.

Nonresidential construction shall either be elevated in conformance with subsection (3)a, b, c or d of this section. Alternatively, the structure(s), or together with attendant utility and sanitary facilities, shall:

1.

Be floodproofed so that below the regulatory flood elevation the structure is watertight with walls substantially impermeable to the passage of water. This is not to be construed as permitting, promising, or otherwise allowing subgrade structures, including basements, for new construction or substantial improvements, except as expressly stated in this ordinance to the contrary.

2.

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

3.

Be certified by a state licensed, registered professional engineer or architect that the standards of this subsection (3) and otherwise as to floodproofing are satisfied. Such certifications shall be provided to the floodplain administrator prior to issuance of a flood use permit for proposed construction, and prior to occupancy.

f.

Require, for all new construction, subsequent improvements, and substantial improvements of nonresidential structures, that fully enclosed areas below the lowest floor that are usable solely for parking of vehicles, building access or storage in an area other than a basement, and which are subject to flooding, 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 be certified by a state licensed, registered professional engineer or architect to meet or exceed the following minimum criteria:

1.

A minimum of two openings on different sides of each enclosed area, a total net area of not less than one square inch for every square foot of enclosed area subject to flooding, shall be provided.

2.

The bottom of all openings shall be no higher than one foot above grade. Any area of an opening located above the base flood elevation will not be credited in the calculation.

3.

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

4.

If it is not feasible or desirable to meet the openings criteria stated above, a registered engineer or architect may design and certify that the openings meet the intent of this section.

g.

Manufactured homes shall meet the above standards and also the standards in section 18-82.

h.

Garages and accessory structures.

1.

Attached garages. 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 of floodwaters. See subsection (3)g of this section. Areas of the garage below the regulatory flood elevation must be constructed with flood-resistant materials. See subsection (2) of this section. A garage attached to a nonresidential structure must meet the above requirements or be dry floodproofed.

2.

Detached garages and accessory structures. Accessory structure used solely for parking (2 car detached garages or smaller) or limited storage (small, low-cost sheds), as defined in section 18-25, may be constructed such that its floor is below the regulatory flood elevation, provided the structure is designed and constructed in accordance with the following requirements:

(i)

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

(ii)

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

(iii)

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

(iv)

Any mechanical and utility equipment in the accessory structure must be elevated or floodproofed to or above the regulatory flood elevation;

(v)

The accessory structure must comply with floodplain encroachment provisions in section 18-84; and

(vi)

The accessory structure must be designed to allow for the automatic entry of floodwaters in accordance with subsection (3)g of this section.

i.

Detached garages and accessory structures not meeting the above standards and must be constructed in accordance with all applicable standards in this section.

j.

Setbacks. In addition to other setbacks required by laws, additional setbacks, including setbacks from watercourse banks, may be required by the floodplain board, upon recommendation of the floodplain administrator.

( Ord. No. 2000-00 , § 5.1, 11-6-2000; Ord. No. 2014-01 , § 5, art. 1, 5-19-2014)