Chapter 3.36
WILDLAND-URBAN INTERFACE STANDARDS

Sections:

3.36.000    Scope and objective.

3.36.010    Wildland-urban interface zone designation.

3.36.020    Authority of code official.

3.36.030    Special building construction regulations.

3.36.040    General.

3.36.050    Roof coverings in primary and secondary zones.

3.36.060    Replacement or repair of roof coverings.

3.36.070    Replacement or repair of siding in the primary zone.

3.36.080    Protection of eaves.

3.36.090    Exterior walls in the primary zone.

3.36.100    Unenclosed under-floor protection in the primary zone.

3.36.110    Appendages and projections in the primary zone.

3.36.120    Exterior doors in the primary zone.

3.36.130    Vents in the primary zone.

3.36.140    Detached accessory structures in the primary zone.

3.36.150    Emergency vehicle access.

3.36.160    Defensible space in primary zone.

3.36.170    Fire safety plan in primary zone.

3.36.180    Violation and penalty.

3.36.000 Scope and objective.

(1) Scope. Upon the effective date of the ordinance codified in this chapter, the requirements contained herein shall be applicable to all new structures and additions constructed adjacent to the wildland-urban interface (WUI) boundary as defined by the exposed edge of developed property to unbroken tracts of natural vegetation that constitute the risk of wildland fires. Design and construction of new structures affected shall comply with the provisions of this chapter along with the current provisions contained within the International Fire Code, International Building Code and Wenatchee city zoning code as currently adopted and periodically amended or updated. Should any provision within this chapter conflict with any other provision of the Wenatchee City Code, then this chapter shall control.

(2) Objective. The objective of this chapter is to establish preferred construction materials, methods and planning that reduce the hazards to life and property associated with the building’s ability to withstand exposure to wildfire events. (Ord. 2011-13 § 1)

3.36.010 Wildland-urban interface zone designation.

The code official shall have final authority in determining which properties shall be affected by the WUI zone designation. The determination shall be made based on the property’s location and exposure to large tracts of natural vegetation. Property and structures immediately adjacent to undeveloped land with natural vegetation without fuel breaks establish the interface line or primary zone and are subject to all of the provisions of this chapter. Property and structures located to the east, or the developed side, of the primary zone and within 1,500 feet of the interface line are included in the secondary zone. (Ord. 2011-13 § 1)

3.36.020 Authority of code official.

The chief of the Wenatchee fire department or his/her designee (hereinafter “code official”) is hereby authorized to enforce the provisions of this code. The code official is empowered to render interpretations of this code and to adopt policies and procedures in order to effectuate the implementation and enforcement of the code provisions contained herein. Such interpretations, policies and procedures shall be in accordance with the intent and purpose of this chapter and in conformance with guidelines referenced in the ICC International Wildland-Urban Interface Code and NFPA 1144 Standard for Reducing Structural Ignition Hazards from Wildland Fire, 2008, or as later adopted. (Ord. 2011-13 § 1)

3.36.030 Special building construction regulations.

All buildings and structures in WUI zone shall be constructed in accordance with the International Fire Code, International Building Code, Wenatchee City Code and this chapter.

(1) Exceptions. Detached accessory structures not exceeding 200 square feet in floor area. (Ord. 2011-13 § 1)

3.36.040 General.

Buildings and structures hereafter constructed, modified or relocated into or within the primary WUI zone shall meet the construction requirements in accordance with this chapter. Fire-resistant construction shall be in accordance with WCC 3.36.050 through 3.36.140. (Ord. 2011-13 § 1)

3.36.050 Roof coverings in primary and secondary zones.

All roofs in the primary zone shall have a Class A roof covering or a Class A roof assembly. For roof coverings where the profile allows a space between the roof covering and roof decking, the space at the eave ends shall be fire-stopped to preclude entry of flames or embers, or have one layer of 72-pound mineral-surfaced, nonperforated cap sheathing complying with ASTM D 3909 installed over the combustible decking.

All roofs located in the secondary zone shall have a Class B roof covering or a Class B roof assembly.

Wood shakes and wood shingles are prohibited in primary and secondary zones. (Ord. 2011-13 § 1)

3.36.060 Replacement or repair of roof coverings.

Roof coverings on buildings or structures in existence prior to the adoption of this code that are replaced or have 50 percent or more replaced in a 12-month period shall be replaced with a roof covering as required for new construction based on WCC 3.36.050. (Ord. 2011-13 § 1)

3.36.070 Replacement or repair of siding in the primary zone.

Siding coverings on buildings or structures in existence prior to the adoption of this code that are replaced or have 50 percent or more replaced in a 12-month period shall be replaced with a siding material as required for new construction based on the type of ignition-resistant construction specified in accordance with WCC 3.36.090. (Ord. 2011-13 § 1)

3.36.080 Protection of eaves.

Eaves and soffits shall be protected on the exposed underside by materials approved for a minimum of one-hour fire-resistance-rated construction, one-inch (25.4 mm) nominal fire-retardant-treated lumber or three-quarter-inch (19 mm) nominal fire-retardant-treated plywood, identified for exterior use and meeting the requirements of Section 2303.2 of the International Building Code. Fascias are required and shall be protected on the backside by materials approved for a minimum of one-hour fire-resistance-rated construction or two-inch (51 mm) nominal dimension lumber. (Ord. 2011-13 § 1)

3.36.090 Exterior walls in the primary zone.

Exterior walls of buildings or structures shall be constructed with one of the following methods:

(1) Materials approved for a minimum of one-hour fire-resistance-rated construction on the exterior side.

(2) Approved noncombustible materials.

(3) Heavy timber or log wall construction.

(4) Fire-retardant-treated wood on the exterior side. The fire-retardant-treated wood shall be labeled for exterior use and meet the requirements of Section 2303.2 of the International Building Code. Such material shall extend from the top of the foundation to the underside of the roof sheathing. (Ord. 2011-13 § 1)

3.36.100 Unenclosed under-floor protection in the primary zone.

Buildings or structures shall have all under-floor areas enclosed to the ground with exterior walls in accordance with WCC 3.36.090.

(1) Exception. Complete enclosure may be omitted where the underside of all exposed floors and all exposed structural columns, beams and supporting walls are protected as required for exterior one-hour fire-resistance-rated construction or heavy timber construction. (Ord. 2011-13 § 1)

3.36.110 Appendages and projections in the primary zone.

Unenclosed accessory structures attached to buildings with habitable spaces and projections, such as decks, shall be a minimum of one-hour fire-resistance-rated construction, heavy timber construction or constructed of approved noncombustible materials or fire-retardant-treated wood identified for exterior use and meeting the requirements of Section 2303.2 of the International Building Code.

When the attached structure is located and constructed so that the structure or any portion thereof projects over a descending slope surface greater than 10 percent, the area below the structure shall have all under-floor areas enclosed to within six inches (152 mm) of the ground, with exterior wall construction in accordance with WCC 3.36.090. (Ord. 2011-13 § 1)

3.36.120 Exterior doors in the primary zone.

Exterior doors on exposure sides shall be approved noncombustible construction, solid core wood not less than one and three-quarters inches thick (45 mm), or have a fire protection rating of not less than 20 minutes. Windows within doors shall be rated, multilayered, glazed, or tempered glass.

(1) Exception. Vehicle access doors. (Ord. 2011-13 § 1)

3.36.130 Vents in the primary zone.

Attic ventilation openings, foundation or under-floor vents, or other ventilation openings in vertical exterior walls and vents through roofs shall be designed and approved to prevent flame or ember penetration into the structure or not exceed 144 square inches (0.0929 m2) each. Such vents shall be covered with noncombustible corrosion-resistant mesh with openings not to exceed one-quarter inch (6.4 mm). Attic ventilation openings shall not be located in soffits, in eave overhangs, between rafters at eaves, or in other overhang areas unless protected by designed flame- and ember-resistant approved venting. Gable end and dormer vents shall be located at least 10 feet (3,048 mm) from property lines. Under-floor ventilation openings shall be located as close to grade as practical and comply with ember- and flame-resistant design. (Ord. 2011-13 § 1)

3.36.140 Detached accessory structures in the primary zone.

Detached accessory structures greater than 200 square feet in floor area located less than 50 feet (15,240 mm) from a building containing habitable space shall have exterior walls constructed with materials approved for a minimum of one-hour fire-resistance-rated construction, heavy timber, log wall construction or constructed with approved noncombustible materials on the exterior side. When the detached structure is located and constructed so that the structure or any portion thereof projects over a descending slope surface greater than 10 percent, the area below the structure shall have all under-floor areas enclosed to within six inches (152 mm) of the ground, with exterior wall construction in accordance with WCC 3.36.090 or under-floor protection in accordance with WCC 3.36.100.

(1) Exception. The enclosure may be omitted where the underside of all exposed floors and all exposed structural columns, beams and supporting walls are protected as required for exterior one-hour fire-resistance-rated construction or heavy-timber construction. See WCC 3.36.050 for roof requirements. (Ord. 2011-13 § 1)

3.36.150 Emergency vehicle access.

Emergency vehicle access shall be provided in all designated WUI areas in accordance with the provisions of the International Fire Code, Wenatchee City Code and this chapter. (Ord. 2011-13 § 1)

3.36.160 Defensible space in primary zone.

“Defensible space” means an area either natural or manmade where material capable of allowing a fire to spread unchecked has been treated, cleared or modified to slow the rate and intensity of an advancing wildfire and to create an area for fire suppression operations to occur.

All newly constructed structures in the WUI zone shall be protected by a 30-foot defensible space from undeveloped land. Defensible space may consist of the following, in order of preferred priority: (1) a modified fire-resistive perimeter area within a common lot or roadway outside of individual lots lines; and/or (2) a fire-resistive landscaped yard area within individual lot lines in accordance with National Fire Protection Association (NFPA) Standard 1144, Standard for the Protection of Life and Property from Wildfire. The maximum building envelope for development sites must be identified on each parcel to provide adequate access around the structure for fire protection, and to provide a fire break.

The defensible space shall include a landscape plan and a description of maintenance responsibilities for the property providing the defensible space. Those responsibilities shall be included in the CC&Rs for the property.

Landscaping within defensible space shall have the characteristics of fire-resistive vegetation described as follows:

(1) Growth with little or no accumulation of dead vegetation (either on the ground or standing upright. Although green, both juniper shrubs and arborvitae accumulate large amounts of dead material).

(2) Nonresinous plants (willow, poplar or tulip trees).

(3) Low volume of total vegetation (for example, a grass area as opposed to a forest or shrub-covered land).

(4) Plants with high live fuel moisture (plants that contain a large amount of water in comparison to their dry weight).

(5) Drought-tolerant plants (deeply rooted plants with thick, heavy leaves).

(6) Stands without ladder fuels (plants without small, fine branches and limbs between the ground and the canopy of overtopping shrubs and trees).

(7) Plants requiring little maintenance (slow-growing plants that, when maintained, require little care).

(8) Plants with woody stems and branches that require prolonged heating to ignite.

For reference on specific plants and their characteristics, see http://firewise.org. (Ord. 2011-13 § 1)

3.36.170 Fire safety plan in primary zone.

Prior to preliminary plat approval, a fire safety plan shall be filed with any subdivision or planned unit development within the WUI primary zone that requires compliance with this code. The plan shall be based on a site-specific wildfire risk assessment that includes considerations of project size, location, topography, aspect, flammable vegetation, climatic conditions and fire history. The plan shall address water supply, access, building ignition and fire-resistive factors, fire protection systems and equipment, defensible space and vegetation management.

The fire safety plan and permit application shall be submitted to the code official having jurisdiction, as determined by the Wenatchee fire chief. (Ord. 2011-13 § 1)

3.36.180 Violation and penalty.

Any violation of this chapter constitutes a civil violation as provided in WCC Title 16, for which a monetary penalty may be imposed as provided therein. (Ord. 2014-02 § 2; Ord. 2011-13 § 1)