5-12-53: IFC AMENDMENT, ADD CHAPTER 41, WILDLAND- URBAN INTERFACE (WUI) CODE:
4101 SCOPE. Upon the effective date of this ordinance, the requirements contained herein shall be applicable to all new structures and additions constructed within City of Boise Wildland-Urban Interface (WUI) areas. The design and construction of new structures within WUI areas shall comply with all the provisions of this chapter along with the current provisions contained within the Boise City Code and Boise City Zoning Code as adopted and periodically amended or updated. Should any provision within this chapter conflict with any other provision of Boise City Code, then the more restrictive shall control.
4102 AUTHORITY OF THE CODE OFFICIAL. The fire code official or building code official is hereby authorized to enforce the provisions of this chapter. The fire code official may render interpretations of this code and 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.
4103 PLANS AND SPECIFICATIONS
4103.1 Site Plan. In addition to the requirements for plans in the International Building Code, site plans shall include topography, width and percent of grade of access roads, landscape and vegetation details, locations of structures or building envelopes, existing or proposed overhead utilities, occupancy classification of buildings, types of ignition-resistant construction of buildings, structures and their appendages, roof classification of buildings, and site water supply systems. The code official is authorized to waive or modify the requirement for a site plan where the application for permit is for alteration or repair or where otherwise warranted.
4103.2 Wildfire Safety Plan. Prior to or with a submittal of a preliminary plat or annexation, a Wildfire Safety Plan shall be prepared and submitted to the code official for review and approved as a part of the plans required for a permit. The Wildfire Safety Plan shall be incorporated into the Covenants, Conditions, and Restrictions (CC&Rs) for developments (if established) to ensure implementation, maintenance, and adherence to these requirements.
4103.2.1 General. When required by the code official, a Wildfire Safety Plan shall be prepared.
4103.2.2 Content. The plan shall be based upon a site-specific, wildfire risk assessment that includes considerations of location, topography, aspect, flammable vegetation, climatic conditions and fire history. The plan shall also address water supply, fire department access, requirements for ignition-resistant construction and other ignition-resistance factors, fire protection systems and equipment, defensible space, and vegetation management, audit process, and other information as required by the fire code official.
4103.2.2.1 Vegetation Management. This section shall describe all actions that will be taken to prevent a fire from being carried toward or away from the structure(s), and shall include at least the following information:
1. Methods and timetables for controlling, changing or modifying areas on the property to create and maintain defensible space. Elements of the plan shall include removal of slash, snags, vegetation that may grow into overhead electrical lines, other ground fuels, ladder fuels and dead trees, and the thinning of live trees, landscaping plans, etc.
2. A plan for maintaining the proposed hazardous fuel-reduction and mitigation measures.
3. A plan or process to monitor and report the implementation of the vegetation management actions.
4103.2.3 Maintenance. The Wildfire Safety Plan shall be incorporated into the CC&R's for subdivisions to ensure long-term maintenance and adherence to these requirements.
4103.2.4 Cost. The cost of plan preparation and review shall be the responsibility of the applicant.
4103.2.5 Plan Retention. The plan shall be retained by the code official.
4103.2.6 Qualifications. The plan shall be prepared by a special expert (e.g. Wildfire Mitigation Specialist) or other person demonstrating the competence and relevant wildfire mitigation experience or training. The preparer shall be acceptable and approved by the fire code official.
4104 DEFINITIONS
ACCESSORY STRUCTURE. A building or structure used to shelter or support any material, equipment, chattel or occupancy other than a habitable building.
DEFENSIBLE SPACE. 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-RESISTANCE-RATED CONSTRUCTION. 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 wildland fuels.
FLAME SPREAD INDEX. 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 E 84 or UL 723. Flame spread index ratings and ranges are as follows:
1. Class A - (0 - 25);
2. Class B - (26 - 75);
3. Class C - (76 - 200).
FUEL MODIFICATION. A method of modifying fuel load by reducing the amount of non-fire-resistive vegetation or altering the type of vegetation to reduce the fuel load.
FUEL MOSAIC. A fuel modification system that provides for the creation of islands and irregular boundaries to reduce the visual and ecological impact of fuel modification.
IGNITION-RESISTANT BUILDING MATERIAL. 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 4108.
IGNITION-RESISTANT CONSTRUCTION, CLASS 1 (IR1), AND CLASS 2 (IR2). A schedule of additional requirements for construction in wildland-urban interface areas based on representative fire hazard.
LOG WALL CONSTRUCTION. A type of construction in which exterior walls are constructed of solid wood members and where the smallest horizontal dimension of each solid wood member is at least 6 inches.
MULTILAYERED GLAZED PANELS. Window or door assemblies that consist of two (2) 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 E 136 shall be considered noncombustible within the meaning of this section.
2. Material having a structural base of noncombustible material as defined in Item 1 above, with a surfacing material not over 1/8-inch-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 E 84 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 Item 1. No material shall be classified as noncombustible that is subject to an increase in combustibility or flame spread index, beyond the limits herein established, through the effects of age, moisture or other atmospheric condition.
NONCOMBUSTIBLE ROOF COVERING. A roof covering consisting of any of the following:
1. Cement shingles or sheets;
2. Exposed concrete slab roof;
3. Ferrous or copper shingles or sheets;
4. Slate shingles;
5. Clay or concrete roofing tile;
6. Approved roof covering of noncombustible material.
OPEN BURNING. The burning of materials wherein products of combustion are emitted directly into the ambient air without passing through a stack or chimney from an enclosed chamber. Open burning does not include road flares, smudge-pots and similar devices associated with safety or occupational uses typically considered open flames. Recreational fires or use of portable outdoor fireplaces shall be considered open burning. For the purpose of this definition, a chamber shall be regarded as enclosed when, during the time combustion occurs, only apertures, ducts, stacks, flues, or chimneys necessary to provide combustion air and permit the escape of exhaust gas are open.
SETBACK. Distance from the nearest lot line to any portion of a structure, including appendages (e.g. decks, etc.).
SLOPE. The variation of terrain from the horizontal; the number of feet rise or fall per 100 feet measured horizontally, expressed as a percentage.
SPECIAL EXPERT. An individual who has demonstrated qualifications in a specific area, outside of the practice of architecture or engineering, through education, training, and experience.
STRUCTURE. That which is built or constructed.
SUBDIVISION. The division of a tract, lot or parcel of land into two or more lots, plats, sites or other divisions of land.
TREE CROWN. The primary and secondary branches growing out from the main stem, together with twigs and foliage, normally considered the upper part of the tree.
UNDEVELOPED PROPERTY. Land that is largely in a natural condition, is primarily non-irrigated and non-paved and is often connected to other similarly undeveloped land that constitutes part of the wildland or wildland-urban interface, including natural open space. The code official shall determine when property constitutes undeveloped property.
UNENCLOSED ACCESSORY STRUCTURE. An accessory structure without a complete exterior wall system enclosing the area under roof or floor above.
WILDFIRE. An uncontrolled fire spreading through vegetative fuels, exposing and possibly consuming structures.
WILDFIRE SAFETY PLAN. A document prepared for a specific project or development proposed for wildland-urban interface areas. It describes ways to minimize and mitigate the fire problems created by the project or development, with the purpose of reducing the impact on the community's fire protection delivery system.
WILDLAND. An area in which development is essentially nonexistent, except for roads, railroads, power lines and similar facilities.
WILDLAND-URBAN INTERFACE AREA. That geographical area where structures and other human development meets or intermingles with wildland or vegetative fuels.
4105 WILDLAND-URBAN INTERFACE (WUI) AREA DESIGNATIONS
4105.1 Declaration. The fire code official shall declare the wildland-urban interface (WUI) and ignition-resistant (IR) construction areas within the jurisdiction. These areas and designations shall be based on best available data.
4105.2 Mapping. Wildland-urban interface areas shall be recorded on maps available for inspection by the public. The wildland-urban interface area boundary shall correspond to natural or manmade features. These maps are generalized depictions of the WUI area boundaries. The fire code official shall have final authority in determining which lots shall be included within each area.
4105.2.1 General IR1 Areas. Areas required to utilize Class 1 Ignition-Resistant Construction (IR1) shall generally depict foothills fire hazard areas. Further, as the city annexes land to the north and west, the IR1 areas will be automatically modified to include annexed lands that are generally north and west of Hill Road.
4105.2.2 General IR2 Areas. Areas required to utilize Class 2 Ignition-Resistant Construction (IR2) shall generally depict valley, desert, and other occluded fire hazard areas that do not include sloped terrain. Interior lots for IR1 areas may be allowed to utilize Class 2 Ignition-Resistant Construction (IR2) as determined by the code official.
4105.2.3 Other Areas. The fire code official shall determine additional areas at threat from wildfire. These areas may include properties adjacent to occluded undeveloped properties, in areas not historically considered wildland-urban interface.
4105.3 Review of Wildland-Urban Interface Areas. The fire code official shall reevaluate and recommend modification to the wildland-urban interface areas in accordance with Section 4105.1 on a 5-year basis, or more frequently as deemed necessary by the fire code official.
4106 ACCESS AND WATER SUPPLY
4106.1 General. Access and water supply shall be in accordance with the International Fire Code and Boise City Code.
4107 BUILDING CONSTRUCTION REGULATIONS
4107.1 Scope. Buildings and structures hereafter constructed, modified or relocated into or within WUI areas shall meet the construction requirements in accordance with this code, the International Building Code, International Fire Code and Boise City Code.
Exceptions:
1. Detached accessory structures not exceeding 200 square feet in floor area where located 50 feet or more from buildings containing habitable spaces.
2. Agricultural buildings located 50 feet or more from buildings containing habitable spaces.
4107.2 Objective. The objective of Sections 4107 through 4113 is to establish minimum standards to locate, design and construct buildings and structures or portions thereof for the protection of life and property, to resist damage from wildfires, and to mitigate building and structure fires from spreading to wildland fuels. The minimum standards set forth in this chapter vary with the critical fire weather, slope and fuel type, to provide increased protection, above the requirements set forth in the International Building Code, from the various levels of hazards.
4107.3 Fire-Resistance-Rated Construction. Where this code requires 1-hour fire-resistance-rated construction, the fire-resistance rating of building elements, components or assemblies shall be determined in accordance with the test procedures set forth in ASTM E 119 or UL 263.
Exceptions:
1. The fire-resistance rating of building elements, components or assemblies based on the prescriptive designs prescribed in Section 721 of the International Building Code.
2. The fire-resistance rating of building elements, components or assemblies based on the calculation procedures in accordance with Section 722 of the International Building Code.
4107.4 Setbacks to Undeveloped Natural Open Space. The minimum required setback from any portion of a structure, including appendages, to undeveloped natural open space shall not be less than 30 feet. Setback distances may be increased, depending upon topographical or other site-specific conditions, as determined by the code official.
4108 IGNITION-RESISTANT CONSTRUCTION AND MATERIAL
4108.1 General. Buildings and structures hereafter constructed, modified or relocated into or within wildland-urban interface areas shall meet site-specific construction requirements based on a determination by the code official. Class 1 (IR1), and Class 2 (IR2), ignition-resistant construction shall be in accordance with Sections 4109, and 4110, respectively. Materials required to be ignition-resistant materials shall comply with the requirements of Section 4108.2, the International Building Code, International Fire Code and Boise City Code.
4108.2 Ignition-Resistant Building Material. Ignition-resistant building materials shall comply with any one of the following:
1. Material shall be tested on all sides with the extended ASTM E 84 (UL 723) test or ASTM E 2768, except panel products shall be permitted to test only the front and back faces. Panel products shall be tested with a ripped or cut longitudinal gap of 1/8 inch (3.2 mm). Materials that, when tested in accordance with the test procedures set forth in ASTM E 84 or UL 723 for a test period of 30 minutes, or with ASTM E 2768, comply with the following:
1.1. Flame spread. Material shall exhibit a flame spread index not exceeding 25 and shall not show evidence of progressive combustion following the extended 30-minute test.
1.2. Flame front. Material shall exhibit a flame front that does not progress more than 10-1/2 feet (3200 mm) beyond the centerline of the burner at any time during the extended 30-minute test.
1.3. Weathering. Ignition-resistant building materials shall maintain their performance in accordance with this section under conditions of use. Materials shall meet the performance requirements for weathering (including exposure to temperature, moisture and ultraviolet radiation) contained in the following standards, as applicable to the materials and the conditions of use:
1.3.1. Method A "Test Method for Accelerated Weathering of Fire-Retardant-Treated Wood for Fire Testing" in ASTM D 2898, for fire-retardant-treated wood, wood-plastic composite and plastic lumber materials.
1.3.2. ASTM D 7032 for wood-plastic composite materials.
1.3.3. ASTM D 6662 for plastic lumber materials.
1.4. Identification. All materials shall bear identification showing the fire test results.
Exception: Materials comprised of a combustible core and a noncombustible exterior covering, comprised of either aluminum at a minimum 0.019 inch (0.48 mm) thickness or corrosion-resistant steel at a minimum 0.0149 inch (0.38 mm) thickness shall not be required to be tested with a ripped or cut longitudinal gap.
2. Noncombustible material. Material that meets the definition of noncombustible in Section 4104.
3. Fire-retardant-treated wood. Fire-retardant-treated wood identified for exterior use and meeting the requirements of Section 2303.2 of the International Building Code.
4. Fire-retardant-treated wood roof coverings. Roof assemblies containing fire-retardant-treated wood shingles and shakes that comply with the requirements of Section 1505.6 of the International Building Code and classified as Class A roof assemblies as required in Section 1505.2 of the International Building Code.
4109 CLASS 1 IGNITION-RESISTANT CONSTRUCTION (IR1)
4109.1 General. Class 1 ignition-resistant construction shall be in accordance with Sections 4109.2 through 4109.11.
4109.2 Roof Covering. Roofs shall have a roof assembly or roof covering, which shall comply with a Class A rating when tested in accordance with ASTM E 108 or UL 790. 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 sheet complying with ASTM D 3909 installed over the combustible decking.
Exceptions:
1. Class A roof assemblies include those with coverings of brick, masonry or an exposed concrete roof deck.
2. Class A roof assemblies also include ferrous or copper shingles or sheets, metal sheets and shingles, clay or concrete roof tile or slate installed on noncombustible decks or ferrous, copper or metal sheets installed without a roof deck on noncombustible framing.
3. Class A roof assemblies include minimum 16 oz/sq. ft. copper sheets installed over combustible decks.
4109.2.1 Roof Valleys. When provided, valley flashings shall be not less than 0.019 inch (No. 26 galvanized sheet gage) corrosion-resistant metal installed over a minimum 36-inch-wide underlayment consisting of one layer of 72-pound mineral-surfaced, nonperforated cap sheet complying with ASTM D 3909 running the full length of the valley.
4109.3 Protection of Eaves. Eaves and soffits shall be protected on the exposed underside by ignition-resistant materials in accordance with Section 4108.2 or by materials approved for not less than 1-hour fire resistance-rated construction, 2-inch nominal dimension lumber, or 1-inch nominal fire-retardant-treated lumber or 3/4-inch nominal fire-retardant-treated plywood, identified for exterior use and meeting the requirements of Section 2303.2 of the International Building Code. Fascia's are required and shall be protected on the backside by ignition-resistant materials in accordance with Section 4108.2 or by materials approved for not less than 1-hour fire-resistance-rated construction or 2-inch nominal dimension lumber.
4109.4 Gutters and Downspouts. Gutters and downspouts shall be constructed of noncombustible material. Gutters shall be provided with an approved means to prevent the accumulation of leaves and debris in the gutter.
4109.5 Exterior Walls. Exterior walls of buildings or structures shall be constructed with one of the following methods:
1. Materials approved for not less than 1-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;
5. Ignition-resistant materials complying with Section 4108.2 on the exterior side.
Such material shall extend from the top of the foundation to the underside of the roof sheathing.
4109.6 Underfloor Enclosure. Buildings or structures shall have underfloor areas enclosed to the ground with exterior walls in accordance with Section 4109.5.
Exception: Complete enclosure shall not be required where the underside of exposed floors and exposed structural columns, beams and supporting walls are protected as required for exterior 1-hour fire-resistance-rated construction or heavy timber construction or fire-retardant-treated wood. The fire-retardant-treated wood shall be labeled for exterior use and meet the requirements of Section 2303.2 of the International Building Code.
4109.7 Appendages and Projections. Unenclosed accessory structures attached to buildings with habitable spaces and projections, such as decks, shall be not less than 1-hour fire-resistance-rated construction or constructed of one of the following:
1. Approved noncombustible materials;
2. Fire-retardant-treated wood identified for exterior use and meeting the requirements of Section 2303.2 of the International Building Code;
3. Ignition-resistant building materials in accordance with Section 4108.2;
4. Heavy timber construction with following minimum dimensions: 6 by 6-inches for columns, 4 by 8-inches for joists, 4 by 10-inches or 6 by 8-inches for beams and 3 by 4-inches for ledgers.
4109.7.1 Underfloor Areas. Where 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 underfloor areas enclosed to within 6 inches of the ground, with exterior wall construction in accordance with Section 4109.5.
4109.8 Exterior Glazing. Exterior windows, window walls and glazed doors, windows within exterior doors, and skylights shall be tempered glass, multilayered glazed panels, glass block or have a fire protection rating of not less than 20 minutes.
4109.9 Exterior Doors. Exterior doors shall be approved noncombustible construction, solid core wood not less than 1-3/4 inches thick or have a fire protection rating of not less than 20 minutes. Windows within doors and glazed doors shall be in accordance with Section 4109.8.
Exception: Vehicle access doors.
4109.10 Vents. Attic ventilation openings, foundation or underfloor vents, or other ventilation openings in vertical exterior walls and vents through roofs shall not exceed 144 square inches each. Such vents shall be covered with noncombustible corrosion-resistant mesh with openings not to exceed 1/8 inch or shall be designed and approved to prevent flame or ember penetration into the structure.
Exceptions:
1. Clothes dryer and plumbing vents are exempt from the installation of the mesh covering.
2. Appliance vents that are prohibited by the manufacturer to be covered by mesh.
3. Where noncombustible exhaust vents with louvers, and 1/4-inch wire mesh screens are provided, which prevent the intrusion of embers into a vent opening.
4. Where no acceptable alternative exists for air intake vents.
4109.10.1 Vent Locations. Attic ventilation openings shall not be located in soffits, in eave overhangs, between rafters at eaves, or in other overhang areas. Gable end and dormer vents shall be located at least 10 feet from lot lines. Underfloor ventilation openings shall be located as close to grade as practical.
Exception: Fire-rated vents designed to prevent flame or ember penetration into the structure may be allowed as approved by the fire code official.
4109.10.2 Vent Materials. Plumbing and appliance vents are not required to be of a noncombustible material unless required by the manufacturer of the appliance.
4109.11 Detached Accessory Structures. Detached accessory structures, located less than 50 feet from a building containing habitable space shall have exterior walls constructed with materials approved for not less than 1-hour fire-resistance-rated construction, heavy timber, log wall construction, or constructed with approved noncombustible materials or 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.
4109.11.1 Underfloor Areas. Where 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 underfloor areas enclosed to within 6 inches of the ground, with exterior wall construction in accordance with Section 4109.5 or underfloor protection in accordance with Section 4109.6.
Exception: The enclosure shall not be required where the underside of exposed floors and exposed structural columns, beams and supporting walls are protected as required for exterior 1-hour fire-resistance-rated construction or heavy-timber construction or 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.
4110 CLASS 2 IGNITION-RESISTANT CONSTRUCTION (IR2)
4110.1 General. Class 2 ignition-resistant construction shall be in accordance with Sections 4109.
Exceptions:
1. Protection of Eaves. Combustible eaves, fascia's and soffits shall be enclosed with solid materials with a minimum thickness of 3/4 inch. Exposed rafter tails shall not be permitted unless constructed of heavy timber materials.
2. Appendages and Projections. Deck boards with a Class A or Class B flame spread rating are allowed.
4111 INSTALLATION, REPAIR AND REPLACEMENT OF FENCES
4111.1 General. This section shall apply for all new installations of fences and replacement of existing fence sections. All fence and/or gate sections within eight feet (8') of any habitable structure shall be constructed of noncombustible materials only. Combustible fencing shall not be allowed within eight feet (8') of a habitable structure.
4112 REPLACEMENT OR REPAIR OF ROOF COVERINGS
4112.1 General. The roof covering 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 required for new construction based on the type of ignition-resistant construction specified in accordance with Section 4108 through 4111.
4113 REPLACEMENT OR REPAIR OF SIDING
4113.1 General. The siding 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 siding required for new construction based on the type of ignition-resistant construction specified in accordance with Section 4108 through 4110.
4114 GENERAL WILDFIRE PREVENTION AND MITIGATION REQUIREMENTS
4114.1 Scope. The provisions of Sections 4114 through 4121 establish general requirements for new and existing buildings, structures and premises located within wildland-urban interface areas.
4114.2 Objective. The objective of Sections 4114 through 4121 is to establish minimum requirements to mitigate the risk to life and property from wildland fire exposures, exposures from adjacent structures and to mitigate structure fires from spreading to wildland fuels.
4115 DEFENSIBLE SPACE
4115.1 General. Defensible space shall comply with 4115.2 to 4115.3 and be maintained in accordance with Section 4116.
Exception: For existing structures, constructed prior to 2011, this provision applies only, if in the opinion of the fire code official, the situation constitutes a distinct hazard to life or property.
4115.2 Objective. Provisions of this section are intended to modify the fuel load in areas adjacent to structures to create a defensible space.
4115.3 Fuel Modification. Buildings or structures in designated wildland-urban interface (WUI) areas, shall comply with defensible space fuel modification distances as required by the code official. Fuel modification distance shall be at least 30 feet. Distances shall be measured on a horizontal plane from the perimeter or projection of the building or structure. Distances may be increased by the code official per requirements in the Wildfire Safety Plan, or because of other site-specific analysis based on local conditions.
Exception: Fuel modification from any portion of the structure, including appendages, to a lot line that adjoins a neighboring residential lot or development. The fuel modification in this area shall be to the lot line if the distance is less than 30 feet.
4115.3.1 Responsible Party. Persons owning, leasing, controlling, operating or maintaining buildings or structures requiring defensible spaces are responsible for modifying or removing non-fire-resistive vegetation on the property owned, leased or controlled by said person.
4115.3.2 Trees. Trees are allowed within the defensible space, provided the horizontal distance between crowns of adjacent trees and crowns of trees and structures, overhead electrical facilities or unmodified fuel is not less than 10 feet.
4115.3.3 Groundcover. Deadwood and litter shall be regularly removed from trees. Where ornamental vegetative fuels or cultivated ground cover, such as green grass, ivy, succulents or similar plants are used as ground cover, they are allowed to be within the designated defensible space, provided they do not form a means of transmitting fire from the native growth to any structure.
4115.3.4 Fuel-Free Area. A fuel-free area of 5 feet is required around all structures. This area shall utilize and maintain only approved fire-resistant vegetation and noncombustible mulches (e.g. rock mulch).
4116 MAINTENANCE OF DEFENSIBLE SPACE
4116.1 General. Defensible spaces required by Section 4115 shall be maintained in accordance with Section 4116.
Exception: For existing structures, constructed prior to 2011, this provision applies only, if in the opinion of the fire code official, the situation constitutes a distinct hazard to life or property.
4116.2 Modified Area. Non-fire-resistive vegetation or growth shall be kept clear of buildings or structures, in accordance with Section 4115, in such a manner as to provide a clear area for fire suppression operations.
4116.3 Responsibility. Persons owning, leasing, controlling, operating or maintaining buildings or structures are responsible for the maintenance of defensible spaces. Maintenance of the defensible space shall include modifying or removing non-fire-resistive vegetation and keeping leaves, needles and other dead vegetative material regularly removed from roofs of buildings and structures.
4116.4 Trees. Tree crowns extending to within 10 feet of any structure shall be pruned to maintain a minimum horizontal clearance of 10 feet. Tree crowns within the defensible space shall be pruned to remove limbs located less than 6 feet above the ground surface adjacent to the trees.
Exception: Shorter-stature trees shall be pruned to remove all limbs located above the ground to 1/3 of the tree crown height (e.g., a nine-foot tree shall be limbed up three feet from the ground).
4116.4.1 Chimney Clearance. Portions of tree crowns that extend to within 10 feet of the outlet of a chimney shall be pruned to maintain a minimum horizontal clearance of 10 feet.
4116.4.2 Deadwood Removed. Deadwood and litter shall be regularly removed from trees.
4116.5 Water Supply. Defensible space shall be provided around water tank structures, water supply pumps and pump houses in accordance with Section 4115.
4117 SPARK ARRESTERS
4117.1 General. Chimneys serving fireplaces, barbecues, incinerators or decorative heating appliances in which solid or liquid fuel is used, shall be provided with a spark arrester. Spark arresters shall be constructed of woven or welded wire screening of 12 USA standard gage wire (0.1046 inch) having openings not exceeding 1/2 inch.
4117.2 Net Free Area. The net free area of the spark arrester shall not be less than four times the net free area of the outlet of the chimney.
4118 STORAGE OF FIREWOOD AND COMBUSTIBLE MATERIALS
4118.1 General. Firewood and combustible material shall not be stored in unenclosed spaces beneath buildings or structures, or on decks or under eaves, canopies or other projections or overhangs. When required by the code official, unenclosed storage of firewood and combustible material in the defensible space shall be located a minimum of 20 feet from structures and separated from the crown of trees by a minimum horizontal distance of 15 feet.
4118.2 Storage for Off-Site Use. Firewood and combustible materials not for consumption on the premises shall be stored so as to not pose a hazard.
4119 VEGETATION CONTROL
4119.1 General. Vegetation control shall comply with Sections 4119.2 through 4119.4.
4119.2 Clearance of Brush or Vegetative Growth from Roadways. The code official is authorized to require areas within 10 feet on each side of portions of fire apparatus access roads and driveways to be cleared of non-fire-resistive vegetation growth.
Exception: Single specimens of trees, ornamental vegetative fuels or cultivated ground cover, such as green grass, ivy, succulents or similar plants used as ground cover, provided they do not form a means of readily transmitting fire.
4119.2.1 Erosion Control. Vegetation should be trimmed to not less than 6" in height on sloped terrain to maintain slope stability for erosion control.
4119.3 Clearance of Brush and Vegetative Growth from Electrical Transmission and Distribution Lines. Clearance of brush and vegetative growth from electrical transmission and distribution lines shall be in accordance with Sections 4119.3.1 through 4119.3.2.1.
Exception: Sections 4119.3.1 through 4119.3.2.1 do not authorize persons not having legal right of entry to enter on or damage the property of others without consent of the owner.
4119.3.1 Support Clearance. Persons owning, controlling, operating or maintaining electrical transmission or distribution lines shall have the following programs in place:
1. A vegetation management program in accordance with the National Electrical Safety Code ("NESC").
2. A transmission and distribution line inspection program in accordance with the NESC.
Exception: Lines used exclusively as telephone, telegraph, messenger call, alarm transmission or other lines classed as communication circuits by a public utility.
4119.3.2 Electrical Distribution and Transmission Line Clearances. Clearances between vegetation and electrical lines shall be in accordance with the provisions of the NESC.
4119.3.2.1 Electrical Power Line Emergencies. During emergencies, the utility shall perform the required work to the extent necessary to clear the hazard. An emergency can include situations such as trees falling into power lines, or trees in violation of clearance requirements in accordance with the NESC.
4119.4 Correction of Condition. The code official is authorized to give notice to the owner of the property of which conditions regulated by Section 4119 exist to correct such conditions. If the owner fails to correct such conditions, the legislative body of the jurisdiction is authorized to cause the same to be done and make the expense of such correction a lien on the property where such condition exists.
4120 ACCESS RESTRICTIONS
4120.1 Restricted Entry. The code official is authorized to determine and publicly announce when wildland-urban interface areas shall be closed to entry and when such areas shall again be opened to entry. Entry on and occupation of wildland-urban interface areas, except public roadways, inhabited areas or established trails and campsites that have not been closed during such time when the wildland-urban interface area is closed to entry, is prohibited.
Exceptions:
1. Residents and owners of private property within wildland-urban interface areas and their invitees and guests going to or being on their lands.
2. Entry, in the course of duty, by peace or police officers, and other duly authorized public officers, members of a fire department and members of the Wildland Firefighting Service.
4121 IGNITION SOURCE CONTROL
4121.1 General. Ignition sources shall be controlled in accordance with Sections 4121.2 through 4121.8.
4121.2 Objective. Regulations in this section are intended to provide the minimum requirements to prevent the occurrence of wildfires.
4121.3 Clearance from Ignition Sources. Clearance between ignition sources and grass, brush or other combustible materials shall be maintained at not less than 30 feet.
4121.4 Smoking. Where required by the code official, signs shall be posted stating NO SMOKING. Persons shall not smoke within 15 feet of combustible materials or non-fire-resistive vegetation.
Exception: Places of habitation or in the boundaries of established smoking areas or campsites as designated by the code official.
4121.5 Equipment and Devices Generating Heat, Sparks or Open Flames. Equipment and devices generating heat, sparks or open flames capable of igniting nearby combustibles shall not be used in wildland-urban interface areas without approval by the fire code official.
Exception: Use of approved equipment within inhabited premises or designated campsites that are not less than 30 feet from grass-, grain-, brush- or forest-covered areas.
4121.6 Fireworks. All fireworks, including non-aerial common fireworks, shall not be used or possessed in an IR1 wildland-urban interface area per Section 4105.2. A reduction of any requirements for a lot in an IR1 area does not constitute a change for the purposes of this section.
Exception: Fireworks allowed by the code official, under permit, in accordance with the International Fire Code where not prohibited by applicable local or state laws, ordinances and regulations.
4121.6.1 Authority to Seize. The code official is authorized to seize, take, remove or cause to be removed fireworks in violation of this section.
4121.7 Outdoor Fires. Outdoor fires in wildland-urban interface areas shall comply with this section, the International Fire Code and Boise City Code.
4121.7.1 General. Persons shall not build, ignite or maintain any outdoor fire of any kind for any purpose, in an IR1 wildland-urban interface area, except by the authority of a written permit from the code official. Outdoor fires on residential lots or designated campsites, where such fires are in an outdoor fireplace, incinerator, or grill, shall be located not less than 30 feet from any combustible material or non-fire-resistive vegetation; and shall have openings protected with an approved spark arrestor, screen or door, unless otherwise approved by the code official.
Exception:
Propane-fired or natural gas-fired outdoor fireplaces, on residential lots, which are located not less than 15 feet from any combustible material or non-fire-resistive vegetation.
4121.8 Incinerators, Outdoor Fireplaces, Permanent Barbecues and Grills. Incinerators, outdoor fireplaces, permanent barbecues and grills shall not be built, installed or maintained in wildland-urban interface areas without approval of the code official.
4121.8.1 Maintenance. Incinerators, outdoor fireplaces, permanent barbecues and grills shall be maintained in good repair and in a safe condition at all times. Openings in such appliances shall be provided with an approved spark arrestor, screen or door.
Exception: Where approved by the code official, unprotected openings in barbecues and grills necessary for proper functioning.
(Ord. 48-20, 12-8-2020, eff. 1-1-2021; amd. Ord. 7-25, 2-25-2025)
