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    Definitions.

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, soffits, fascias and gutters in the primary zone.

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.

3.36.135    Spark arrestors in the primary and secondary zones.

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    Landscaping in the primary zone.

3.36.180    Fire protection plan in primary zone.

3.36.185    Fire flow and hydrants in primary zone.

3.36.190    Violation and penalty.

3.36.000 Scope and objective.

(1) Scope. The provisions of this code shall apply to the construction, alteration, movement, repair, maintenance and use of any building, structure or premises within the wildland-urban interface areas in this jurisdiction.

Buildings or conditions in existence at the time of the adoption of this code are allowed to have their use or occupancy continued, if such condition, use or occupancy was legal at the time of the adoption of this code; provided, that such continued use does not constitute a distinct danger to life or property.

Buildings or structures moved into or within the jurisdiction shall comply with the provisions of this code for new buildings or structures.

(2) Objective. The objective of this code is to establish minimum regulations consistent with nationally recognized good practice for the safeguarding of life and for property protection. Regulations in this code are intended to mitigate the risk to life and structures from intrusion of fire from wildland fire exposures and fire exposures from adjacent structures and to mitigate structure fires from spreading to wildland fuels. The extent of this regulation is intended to be tiered commensurate with the relative level of hazard present.

The unrestricted use of property in wildland-urban interface areas is a potential threat to life and property from fire and resulting erosion. Safeguards to prevent the occurrence of fires and to provide adequate fire protection facilities to control the spread of fire in wildland-urban interface areas shall be in accordance with this code.

This code shall supplement the city’s adopted building and fire codes, providing special regulations to mitigate the fire and life-safety hazards of the wildland-urban interface areas.

(3) Should any provision within this chapter conflict with any other provision of the Wenatchee City Code, then this chapter shall control. (Ord. 2020-33 § 1; Ord. 2011-13 § 1)

3.36.010 Wildland-urban interface zone designation.

(1) The objective of this section is to provide simple baseline criteria for determining wildland-urban interface areas.

(2) Area Designation Declaration. The code official shall declare the wildland-urban interface areas within the city of Wenatchee, with assistance from the fire chief of Chelan County fire district No. 1 and Chelan County fire marshal. The wildland-urban interface area boundary shall correspond to natural or manmade features.

(3) Mapping. The wildland-urban interface areas shall be made available on maps for inspection by the public.

(4) Review of Wildland-Urban Interface Areas. The code official may reevaluate and modify the wildland-urban interface areas on a three-year basis or more frequently as deemed necessary. (Ord. 2020-33 § 1; Ord. 2011-13 § 1)

3.36.020 Authority of code official.

The 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 most current edition of the ICC International Wildland-Urban Interface Code and NFPA 1144 Standard for Reducing Structural Ignition Hazards from Wildland Fire. (Ord. 2020-33 § 1; Ord. 2011-13 § 1)

3.36.030 Special building construction regulations.

Buildings and structures hereafter constructed, modified or relocated into or within the primary or secondary wildland-urban interface zones as delineated on the wildland-urban interface area boundary map shall meet the construction requirements in accordance with this chapter. Fire-resistant construction shall be in accordance with WCC 3.36.050 through 3.36.170. (Ord. 2020-33 § 1; Ord. 2011-13 § 1)

3.36.040 Definitions.

Terms Defined in Other Codes and Terms Not Defined. Where terms are not defined in this code and are defined in other international codes, such terms shall have the meanings ascribed to them as in those codes. Where terms are not defined by this section, such terms shall be as defined elsewhere in the city code or, if not defined, shall have their ordinarily accepted meanings such as the context implies.

“Accessory structure” means a building or structure used to shelter or support any material, equipment, chattel or occupancy other than a habitable building.

“Approved” means acceptable to the code official.

“Building” means any structure intended for supporting or sheltering any occupancy.

“Code official” means the director of the department of community development or his/her designee.

“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.

“Fire protection plan” means a document prepared for a specific project or development proposed for the wildland-urban interface area. It describes ways to minimize and mitigate the fire problems created by the project or development, with the purpose of reducing impact on the community’s fire protection delivery system.

“Fire-resistance-rated construction” means the use of materials and systems in the design and construction of a building or structure to safeguard against the spread of fire within a building or structure and the spread of fire to or from buildings or structures to the wildland-urban interface area.

“Flame spread index” means a comparative measure, expressed as a dimensionless number, derived from visual measurements of the spread of flame versus time for a material tested in accordance with ASTM E84.

“Heavy timber construction” means as described in the International Building Code.

“Ignition-resistant building material” means a type of building material that resists ignition or sustained flaming combustion sufficiently so as to reduce losses from wildland-urban interface conflagrations under worst-case weather and fuel conditions with wildfire exposure of burning embers and small flames, as prescribed in Section 503 of the International Wildland-Urban Interface Code.

“Multilayered glazed panels” means window or door assemblies that consist of two or more independently glazed panels installed parallel to each other, having a sealed air gap in between, within a frame designed to fill completely the window or door opening in which the assembly is intended to be installed.

“Noncombustible,” as applied to building construction material, means a material that, in the form in which it is used, is either one of the following:

(1) Material of which no part will ignite and burn when subjected to fire. Any material conforming to ASTM E136 shall be considered noncombustible within the meaning of this section.

(2) Material having a structural base of noncombustible material as defined in subsection (1) of this definition, with a surfacing material not over one-eighth inch (3.2 mm) thick, which has a flame spread index of 50 or less. “Flame spread index” as used herein refers to a flame spread index obtained according to tests conducted as specified in ASTM E84 or UL 723.

“Noncombustible” does not apply to surface finish materials. Material required to be noncombustible for reduced clearances to flues, heating appliances or other sources of high temperature shall refer to material conforming to subsection (1) of this definition. No material shall be classified as noncombustible that is subject to increase in combustibility or flame spread index, beyond the limits herein established, through the effects of age, moisture or other atmospheric condition.

“Unenclosed accessory structure” means an accessory structure without a complete exterior wall system enclosing the area under roof or floor above.

“Wildfire” means an uncontrolled fire spreading through vegetative fuels, exposing and possibly consuming structures.

“Wildland” means an area in which development is essentially nonexistent, except for roads, railroads, power lines and similar facilities.

“Wildland-urban interface area” means that geographical area where structures and other human development meet or intermingle with wildland or vegetative fuels. (Ord. 2020-33 § 1; 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.

Penetrations through the roof shall be constructed of metal or be listed for use in a Class A roof assembly.

Ridge vents shall be a Class A type ridge vent.

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

Wood shake and wood shingle roofs are prohibited in primary and secondary zones. (Ord. 2020-33 § 1; 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. 2020-33 § 1; Ord. 2011-13 § 1)

3.36.070 Replacement or repair of siding in the primary zone.

Siding coverings on buildings or structures in the primary zone 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. 2020-33 § 1; Ord. 2011-13 § 1)

3.36.080 Protection of eaves, soffits, fascias and gutters in the primary zone.

Eaves and soffits in the primary zone shall be protected on the exposed underside by materials approved for a minimum of one-hour fire-resistance-rated construction, noncombustible material, 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, two-inch (51 mm) nominal dimension lumber or approved noncombustible materials.

Gutters and Downspouts. Gutters and downspouts in the primary zone shall be constructed of noncombustible material. (Ord. 2020-33 § 1; Ord. 2011-13 § 1)

3.36.090 Exterior walls in the primary zone.

Exterior walls of buildings or structures in the primary zone 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. 2020-33 § 1; Ord. 2011-13 § 1)

3.36.100 Unenclosed under-floor protection in the primary zone.

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

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, heavy timber construction or approved noncombustible materials and the surface below the under-floor area is a noncombustible surface. (Ord. 2020-33 § 1; 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, in the primary zone, 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. The surface below the under-floor area shall be a noncombustible surface.

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. 2020-33 § 1; Ord. 2011-13 § 1)

3.36.120 Exterior doors in the primary zone.

Exterior doors in the primary zone 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. 2020-33 § 1; Ord. 2011-13 § 1)

3.36.130 Vents in the primary zone.

Eave, soffit, gable end and ridge vents, foundation vents and other ventilation openings in exterior walls or on roofs shall be flame- and ember-resistant listed vents complying with ASTM E2886 or CalFire SFM12-7A or part of a listed Class A roof assembly.

Air intakes into structures shall be covered with metal wire mesh with openings that do not exceed one-eighth inch. Such air intake openings shall connect to 26-gauge metal ducts for a minimum of six feet in length from the intake.

Exhaust terminations shall be metal with an integral backdraft damper at the termination point. (Ord. 2020-33 § 1; Ord. 2011-13 § 1)

3.36.135 Spark arrestors in the primary and secondary zones.

Chimneys attached to any appliance or fireplace that burns solid fuel shall be equipped with an approved spark arrestor. The spark arrestor screen shall have heat and corrosion resistance equivalent to 12-gauge wire, 19-gauge galvanized wire or 24-gauge stainless steel wire. The net free area of the spark arrestor shall not be less than four times the net free area of the outlet of the chimney. Openings shall not permit the passage of spheres having a diameter larger than one-half inch. (Ord. 2020-33 § 1)

3.36.140 Detached accessory structures in the primary zone.

All detached accessory structures shall have exterior walls constructed with materials approved for a minimum of one-hour fire-resistance-rated construction, heavy timber 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 and the surface below the under-floor area is a noncombustible surface. See WCC 3.36.050 for roof requirements. (Ord. 2020-33 § 1; 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. 2020-33 § 1; Ord. 2011-13 § 1)

3.36.160 Defensible space in primary zone.

All newly constructed structures in the primary zone shall be protected by a 30-foot defensible space from undeveloped land, except that structures located in the residential foothills low zoning district shall comply with the following defensible space requirements:

One-hundred-foot minimum defensible space from undeveloped land for structures adjacent to the westerly and northerly native wildland fuels.

Exceptions.

(1) This distance can be reduced to 70 feet if there is a street between the structures and the native wildland fuels.

(2) This distance can be reduced to 85 feet if there is a gravel fire apparatus access road between the structures and the native wildland fuels.

Fifty-foot minimum defensible space from undeveloped land for structures on or at the top of the slopes on the easterly side of the zone.

Exception. This distance can be reduced to 30 feet from the top of the slope for properties that have a six-foot-tall heat-deflecting, noncombustible landscape retaining wall at the top of the slope or a noncombustible surface on the top 30 feet of a slope.

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 lot 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.

All newly constructed structures in the primary zone shall be protected by a five-foot noncombustible surface extending from any exterior walls of the structure and the outer perimeter of any appendages and projections.

Exception. The five-foot noncombustible surface may be omitted where the exterior walls of the structure and the appendages are constructed with approved noncombustible materials.

Fences and gates less than four feet from a structure shall be noncombustible.

Exception. The five-foot noncombustible surface may be omitted where the exterior walls of the structure and the appendages are constructed with approved noncombustible materials. (Ord. 2020-33 § 1; Ord. 2011-13 § 1)

3.36.170 Landscaping in the primary zone.

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, most juniper shrubs and arborvitae accumulate large amounts of dead material and are therefore not permitted in the primary zone.)

(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 and the following guides:

Fire Resistant Plants for Chelan and Douglas County by Chelan/Douglas County Master Gardener Program.

Fire Resistant Plants for Home Landscapes by Pacific Northwest Extension Service. (Ord. 2020-33 § 1)

3.36.180 Fire protection plan in primary zone.

A fire protection plan shall be filed with any subdivision, short plat or multifamily development within the primary zone. The fire protection plan shall obtain approval of the code official prior to preliminary plat approval or issuance of a building permit for a multifamily development. 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, landscaping, vegetation management and long-term maintenance.

The items addressed in said plan shall be included in the general notes of the final plat. (Ord. 2020-33 § 1; Ord. 2011-13 § 1. Formerly 3.36.170)

3.36.185 Fire flow and hydrants in primary zone.

The minimum fire flow in the primary zone shall be 1,500 gallons per minute, unless deemed technically infeasible by the water purveyor and approved by the fire code official. Where applicable, hydrants shall be placed on the wildland exposure side of streets and other means of vehicular access where hydrants are required. (Ord. 2020-33 § 1)

3.36.190 Violation and penalty.

Any violation of this chapter constitutes a code violation as provided in WCC Title 16, for which a monetary penalty may be imposed as provided therein. (Ord. 2020-33 § 1; Ord. 2014-02 § 2; Ord. 2011-13 § 1. Formerly 3.36.180)