Chapter 5 — SPECIAL BUILDING CONSTRUCTION REGULATIONS

User notes:

About this chapter: Chapter 5 provides regulations that establish minimum standards for the location, design and construction of buildings and structures based on construction within a Fire Hazard Severity Zone or a Wildland-Urban Interface (WUI) Area.

The construction provisions of Chapter 5 are intended to supplement the requirements of the California Building Code and California Residential Code and address mitigation of the unique hazards posed to buildings by wildfire and to reduce the hazards of building fires spreading to wildland fuels. This is accomplished by requiring ignition-resistant construction materials. Construction features regulated include underfloor areas; roof coverings; eaves and soffits; gutters and downspouts; exterior walls, doors and windows; ventilation openings and accessory structures.

Ignition-resistant construction shall be in accordance with Sections 504.2 through 504.11.6 .

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SPECIAL BUILDING CONSTRUCTION REGULATIONS

Roofs shall have a roof assembly that complies with a Class A fire classification when tested in accordance with ASTM E108 or UL 790.

Exceptions: The following assemblies are exempt from testing and shall be considered as equivalent to the Class A fire classification:

1. Roof assemblies with coverings of brick, masonry or an exposed concrete roof deck.
2. Roof assemblies with 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. Roof assemblies with minimum 16 oz/sq ft (0.0416 kg/m [2] ) copper sheets installed over combustible roof decks. 4. Roof assemblies of slate roof covering installed over ASTM D226, Type II underlayment over combustible decks.

504.2.1 Roof covering voids. Where there is a void under the roof covering it shall comply with Section 504.2.1.1 or 504.2.1.2.

504.2.1.1 Airspace under roof covering. Where the roof covering is installed over a combustible deck and the roofing profile creates an airspace under the roof covering, the installation shall comply with the following: 1. A 72 lb. (32.7 kg) cap sheet complying with ASTM D3909 Standard Specification for “Asphalt Rolled Roofing (Glass Felt) Surfaced with Mineral Granules,” shall be installed over the roof deck.

Exception: Cap sheet is not required where not less than 1 inch of mineral wool board or other noncombustible material is located between the roofing material and wood framing or deck. 2. Bird stops shall be used at the eaves where the profile fits, to prevent the entry of debris at the eave. 3. Hip and ridge caps shall be mudded in to prevent intrusion of fire or embers.

504.2.1.2 Roof underlayment. A listed and labeled roof underlayment that has been tested as part of the roof assembly in accor- dance with ASTM E108 or UL 790 for Class A fire classification shall be installed in accordance with the underlayment manufacturer’s installation instructions and listing. Bird stops shall be used at the eaves when the profile fits, to prevent the entry of debris at the eave. Hip and ridge caps shall be mudded in to prevent intrusion of fire or embers.

Exception: Where the roof sheathing is fire-retardant-treated wood labeled for exterior use and complies with Section 2303.2 of the California Building Code, the underlayment shall not be required to comply with a Class A fire classification.

504.2.2 Roof valleys. Where provided, valley flashings shall be not less than 0.019 inch (0.48 mm) (No. 26 galvanized sheet gage) corrosion-resistant metal installed over a minimum 36-inch-wide (914 mm) underlayment consisting of one layer of 72-pound (32.4 kg) mineral-surfaced, nonperforated cap sheet complying with ASTM D3909 running the full length of the valley.

The exposed underside of enclosed roof eaves and soffits shall be protected on the exposed underside by one or more of the following:

1. Noncombustible materials.

2. Ignition-resistant building materials. 3. Materials approved for not less than 1-hour fire-resistance-rated construction on the exterior side, as tested in accordance with ASTM E119 or UL 263.

4. 2-inch (51 mm) nominal dimension lumber . 5. 1-inch (25 mm) nominal fire-retardant-treated lumber or [3] / 4 -inch (19.1 mm) nominal fire-retardant-treated plywood, identified for exterior use and complying with Section 2303.2 of the California Building Code . 6. Boxed-in roof eave soffit assemblies with an underside that meets the performance criteria in Section 504.7.2 when tested in accordance with the test procedures set forth in ASTM E2957. 7. Boxed-in roof eave soffit assemblies with an underside that meets the performance criteria in accordance with the test proce- dures set forth in SFM Standard 12-7A-3.

Facias are required and shall be ignition-resistant building materials , fire-retardant-treated wood labeled for exterior use and complying with Section 2303.2 of the California Building Code, materials approved for not less than 1-hour fire-resistance-rated construction or 2-inch (51 mm) nominal dimension lumber.

504.3.1 Protection of open eaves. The exposed roof deck on the underside of unenclosed roof eaves shall consist of one or more of the following:

1. Noncombustible material.

2. Ignition-resistant building material. 3. Fire-retardant-treated wood labeled for exterior use and complying with Section 2303.2 of the California Building Code. 4. Materials approved for not less than 1-hour fire-resistance-rated construction on the exterior side, as tested in accordance with ASTM E119 or UL 263.

5. 2-inch (51 mm) nominal dimension lumber. 6. One layer of [5] / 8 -inch (16 mm) Type X gypsum sheathing applied behind an exterior covering on the underside of the roof deck.

7. The exterior portion of a 1-hour fire-resistance-rated exterior assembly, as tested in accordance with ASTM E119 or UL 263, applied to the underside of the roof deck designed for exterior fire exposure, including assemblies using the gypsum panel and sheathing products listed in the Gypsum Association Fire Resistance Design Manual.

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Facias, if provided, shall be of fire-retardant-treated wood labeled for exterior use and complying with Section 2303.2 of the Cali- fornia Building Code, ignition-resistant building materials, materials approved for not less than 1-hour fire-resistance-rated construction or 2-inch (51 mm) nominal dimension lumber.

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.

Exterior walls of buildings or structures shall be constructed with one or more of the following methods, unless they are covered with an exterior wall covering complying with Sections 504.5.2 and 504.5.2.1:

1. 1-hour fire-resistance-rated construction on the exterior side.

2. Noncombustible materials.

3. Heavy timber. Assembly of sawn lumber or glue-laminated wood with the smallest minimum nominal dimension of 4 inches (102 mm). Sawn or glue-laminated planks splined, tongue-and-grove or set close together and well spiked. 4. Log wall construction. 5. Wall assemblies that have been tested in accordance with the test procedures for a 10-minute direct flame contact exposure test set forth in ASTM E2707 with the conditions of acceptance shown in Section 504.9.3. 6. Wall assemblies that meet the performance criteria in accordance with the test procedures for a 10-minute direct flame contact exposure test set forth in SFM Standard 12-7A-1. 7. Wall assemblies suitable for exterior fire exposure containing one layer of [5] / 8 -inch (15.9 mm) Type X gypsum sheathing applied behind the exterior wall covering or cladding on the exterior side of the framing. 8. Wall assemblies suitable for exterior fire exposure with a 1-hour fire-resistance rating, rated from the exterior side, as tested in accordance with ASTM E119 or UL 263.

9. Fire-retardant-treated wood labeled for exterior use and complying with Section 2303.2 of the California Building Code .

Such material shall extend from the top of the foundation to the underside of the roof sheathing.

504.5.1 Flashing. A minimum of 6 inches (152 mm) of metal flashing or noncombustible material applied vertically on the exterior of the wall shall be installed at the ground, decking and roof intersections.

504.5.2 Exterior wall coverings. Exterior wall coverings shall comply with one or more of the following requirements:

1. Noncombustible material.

2. Ignition-resistant building material labeled for exterior use. 3. Fire-retardant-treated wood labeled for exterior use and complying with the requirements of Section 2303.2 of the Califor- nia Building Code. 4. Fire-retardant-treated wood shingles and shakes which have been qualified in accordance with Section 1505.6 of the Cali- fornia Building Code for use as “Class B” roof covering shall be an acceptable alternative wall covering material where installed over solid sheathing.

Exception: Exterior wall coverings which are a component of an approved wall assembly complying with Section 504.5.

504.5.2.1 Extent of exterior wall covering. Where provided, exterior wall coverings shall extend from the top of the foundation to the roof, and terminate at 2-inch (50.8 mm) nominal solid wood blocking between rafters at all roof overhangs, or in the case of enclosed eaves, terminate at the enclosure.

Buildings or structures shall have underfloor areas enclosed to the ground with exterior walls in accordance with Section 504.5.

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 California Building Code .

Unenclosed accessory structures attached to buildings with habitable spaces and projections, other than decks, shall be heavy timber construction or constructed of one of the following:

1. Noncombustible materials.

2. Fire-retardant-treated wood identified for exterior use and meeting the requirements of Section 2303.2 of the California Building Code .

3. Ignition-resistant building materials in accordance with Section 503.2. 4. Materials approved for not less than 1-hour fire-resistance-rated construction on the exterior side, as tested in accordance with ASTM E119 or UL 263.

5. One layer of [5] / 8 -inch (15.9 mm) Type X gypsum sheathing applied behind the exterior covering on the underside of the ceiling. 6. The exterior portion of a 1-hour fire-resistance-rated exterior assembly, as tested in accordance with ASTM E119 or UL 263, applied to the underside of the ceiling assembly, including assemblies using the gypsum panel and sheathing products listed in the Gypsum Association Fire Resistance Design Manual. 7. The underside of a floor projection assembly that meets the performance criteria in Section 504.7.2 when tested in accordance with the test procedures set forth in ASTM E2957.

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8. The underside of a floor projection assembly that meets the performance criteria in accordance with the test procedures set forth in SFM Standard 12-7A-3.

504.7.1 Underside of projections. The underside of projections shall be enclosed to grade in accordance with the requirements of this chapter or the underside of the exposed underfloor shall be protected by one or more of the following:

1. Noncombustible material.

2. Ignition-resistant building material shall be labeled for exterior use and shall meet the requirements of Section 503.2. 3. Fire-retardant-treated wood shall be labeled for exterior use and shall meet the requirements of Section 2303.2. 4. Materials approved for not less than 1-hour fire-resistance-rated construction on the exterior side, as tested in accordance with ASTM E119 or UL 263.

gnition-resistant building material shall be labeled for exterior use and shall meet the requirements of Section 503.2._ 3. Fire-retardant-treated wood shall be labeled for exterior use and shall meet the requirements of Section 2303.2. 4. Materials approved for not less than 1-hour fire-resistance-rated construction on the exterior side, as tested in accordance with ASTM E119 or UL 263.

5. One layer of [5] / 8 -inch (15.9 mm) Type X gypsum sheathing applied behind an exterior covering on the underside of the floor projection. 6. The exterior portion of a 1-hour fire-resistance-rated exterior assembly, as tested in accordance with ASTM E119 or UL 263, applied to the underside of the floor, including assemblies using the gypsum panel and sheathing products listed in the Gypsum Association Fire Resistance Design Manual. 7. The underside of a floor assembly that meets the performance criteria in Section 504.7.2 when tested in accordance with the test procedures set forth in ASTM E2957. 8. The underside of a floor assembly that meets the performance criteria in accordance with the test procedures set forth in SFM Standard 12-7A-3.

Exception: Structural columns and beams are not required to be protected in accordance with Section 504.7.1 when constructed with sawn lumber or glue-laminated wood with the smallest minimum nominal dimension of 4 inches (102 mm). Sawn or glue- laminated planks shall be splined, tongue-and-groove, or set close together and well spiked.

504.7.2 Conditions of acceptance for ASTM E2957. The ASTM E2957 test shall be conducted on a minimum of three test specimens and meet the conditions of acceptance in Items 1 through 3. If any one of the three tests does not meet the conditions of acceptance, three additional tests shall be performed. All three additional tests must meet the conditions of acceptance. 1. Absence of flame penetration of the eaves or horizontal projection assembly at any time. 2. Absence of structural failure of the eaves or horizontal projection subassembly at any time. 3. Absence of sustained combustion of any kind at the conclusion of the 40-minute test.

504.7.3 Decks. The walking surface material of decks, porches, balconies and stairs shall comply with the requirements of Sections 504.7.3.1 through 504.7.3.4.

504.7.3.1 Flashing. A minimum of a 6-inch (150 mm) metal flashing, applied vertically on the exterior of the wall, shall be installed at all deck-to-wall intersections.

504.7.3.2 Decking surfaces. The walking surface material of decks, porches, balconies and stairs shall be constructed with any of the following materials: 1. Material that complies with the performance requirements of Section 504.7.3.3 when tested in accordance with ASTM E2632 and ASTM E2726.

2. Ignition-resistant building material that complies with the performance requirements of Section 503.2.4. 3. Material that complies with the performance requirements of both SFM Standard 12-7A-4 and Section 503.2.4. 4. Fire-retardant-treated wood labeled for exterior use and complying with Section 2303.2 of the California Building Code.

5. Noncombustible material.

6. Any material that complies with the performance requirements of SFM Standard 12-7A-4A and any attached exterior wall covering that is noncombustible or ignition-resistant building materials. Exception: Wall material shall be permitted to be of any material that otherwise complies with this chapter when the decking surface material complies with the performance requirements of ASTM E84 or UL 723 with a Class B flame spread index.

7. Any material that complies with the performance requirements of Section 504.7.3.4 when tested in accordance with ASTM E2632 and any attached exterior wall covering that is noncombustible or ignition-resistant building materials. Exception: Wall material shall be permitted to be of any material that otherwise complies with this chapter when the decking surface material complies with the performance requirements of ASTM E84 or UL 723 with a Class B flame spread index.

504.7.3.3 Performance requirements for Section 504.7.3.2, Item 1. Materials shall be tested in accordance with both ASTM E2632 and ASTM E2726 and comply with the conditions of acceptance in Sections 504.7.3.3.1 and 504.7.3.3.2. The material shall also be tested in accordance with ASTM E84 or UL 723 and comply with the performance requirements of Section 503.2.4.

504.7.3.3.1 Conditions of acceptance for ASTM E2632. The ASTM E2632 test shall be conducted on a minimum of three test specimens and meet the conditions of acceptance in Items 1 through 3. If any one of the three tests does not meet the conditions of acceptance, three additional tests shall be performed. All three additional tests must meet the conditions of acceptance. 1. Peak heat release rate of less than or equal to 25 kW/ft2 (269 kW/m2).

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2. Absence of sustained flaming or glowing combustion of any kind at the conclusion of the 40-minute observation period. 3. Absence of falling particles that are still burning when reaching the burner or floor.

504.7.3.3.2 Conditions of acceptance for ASTM E2726. The ASTM E2726 test shall be conducted, using a “Class A” size roof test brand, on a minimum of three test specimens and meet the conditions of acceptance in Items 1 and 2. If any one of the three tests does not meet the conditions of acceptance, three additional tests shall be performed. All three additional tests must meet the conditions of acceptance. 1. Absence of sustained flaming or glowing combustion of any kind at the conclusion of the 40-minute observation period. 2. Absence of falling particles that are still burning when reaching the burner or floor.

e of the three tests_ does not meet the conditions of acceptance, three additional tests shall be performed. All three additional tests must meet the conditions of acceptance. 1. Absence of sustained flaming or glowing combustion of any kind at the conclusion of the 40-minute observation period. 2. Absence of falling particles that are still burning when reaching the burner or floor.

504.7.3.4 Performance requirements for Section 504.7.3.2, Item 7. The ASTM E2632 test shall be conducted on a minimum of three test specimens and the peak heat release rate shall be less than or equal to 25 kW/ft [2] (269 kW/m [2] ). If any one of the three tests does not meet the conditions of acceptance, three additional tests shall be run. All the additional tests shall meet the condi- tion of acceptance. If any one of the three tests does not meet the condition of acceptance, three additional tests shall be performed. All three additional tests must show a peak heat release rate shall be 25 kW/ft2 (269 kW/m2) or less.

Exterior windows, window walls and glazed doors, windows within exterior doors, and skylights shall be constructed of any of the following: 1. Multilayered glazed panels with at least one pane of tempered glass complying with Section 2406 of the California Building Code.

2. Glass block.

3. Glazing with a fire-protection rating of not less than 20 minutes when tested according to NFPA 257 or UL 9, and shall be exempt from the hose stream test. 4. Glazing meeting the performance requirements of SFM Standard 12-7A-2.

504.8.1 Structural glass veneer. The wall assembly behind structural glass veneer shall comply with Section 504.5.

504.8.2 Operable skylights. Operable skylights shall be protected by a noncombustible mesh screen and the dimensions of the openings in the screen shall not exceed [1] / 8 inch (3.2 mm).

Exterior doors shall be constructed in accordance with any of the following:

1. Noncombustible construction .

2. Solid-core wood not less than 1 [3] / 4 inches thick (44 mm) . 3. The exterior door shall be constructed of solid core wood that complies with the following requirements: 3.1. Stiles and rails shall not be less than 1 3/8 inches (35 mm) thick. 3.2. Raised panels shall not be less than 11/4 inches (32 mm) thick, except for the exterior perimeter of the raised panel that shall be permitted to taper to a tongue not less than 3/8 inch (10 mm) thick. 4. Have a fire protection rating of not less than 20 minutes when tested according to NFPA 252, UL 10B or UL 10C . 5. The exterior surface or cladding meeting the performance requirements of Section 504.9.3 when tested in accordance with ASTM E2707.

6. The exterior surface or cladding shall be tested to meet the performance requirements of SFM Standard 12-7A-1.

Windows within doors and glazed doors shall be in accordance with Section 504.8.

504.9.1 Garage doors. Automatic garage door openers for vehicle doors serving a residential building shall be equipped with a battery backup function.

504.9.2 Garage door perimeter gap. Exterior garage doors shall resist the intrusion of embers by preventing gaps between doors and door openings, at the bottom, sides and tops of doors, from exceeding [1] / 8 inch (3.2 mm). Gaps between doors and door openings shall be controlled by one or more of the following methods: 1. Weather-stripping products constructed of materials that which comply with both of the following: 1.1. The tensile strength of the material shall be tested in accordance with ASTM D638 before and after exposure to ASTM G155 for a period of 2,000 hours, and the maximum allowable difference in tensile strength values between exposed and nonexposed samples shall not exceed 10 percent. 1.2. When tested to UL 94, the materials shall have a flammability rating of V-2 or better. 2. Door overlaps onto jambs and headers. 3. Garage door jambs and headers covered with metal flashing.

504.9.3 Conditions of acceptance for ASTM E2707. The ASTM E2707 test shall be conducted on a minimum of three test specimens and meet the conditions of acceptance in Items 1 and 2. If any one of the three tests do not meet the conditions of acceptance, three additional tests shall be performed. All three additional tests must meet the conditions of acceptance. 1. Absence of flame penetration through the wall assembly at any time. 2. Absence of evidence of glowing combustion on the interior surface of the assembly at the end of the 70-minute test.

Where provided, ventilation openings for enclosed attics, gable ends, ridge ends, under eaves and cornices, enclosed eave soffit spaces, enclosed rafter spaces formed where ceilings are applied directly to the underside of roof rafters, underfloor venti

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lation, foundations and crawl spaces, or any other opening intended to permit ventilation, either in a horizontal or vertical surface, shall be in accordance with Section 504.10.1 or Section 504.10.2 to resist building ignition from the intrusion of burning embers and flame through the ventilation openings.

504.10.1 Performance requirements. Ventilation openings shall be fully covered with Wildfire Flame and Ember Resistant vents approved and listed by the California State Fire Marshal, or WUI vents, tested in accordance with ASTM E2886, to demonstrate compliance with all the following requirements:

1. There shall be no flaming ignition of the cotton material during the Ember Intrusion Test.
2. There shall be no flaming ignition during the Integrity Test portion of the Flame Intrusion Test.
3. The maximum temperature of the unexposed side of the vent shall not exceed 662°F (350°C).

504.10.2 Off ridge and ridge vents. Vents that are installed on a sloped roof, such as dormer vents, shall comply with all of the following: 1. Vents shall be covered with a mesh where the dimensions of the mesh therein shall be a minimum of [1] / 16 inch (1.6 mm) and shall not exceed [1] / 8 inch (3.2 mm) in diameter.

2. The vent and mesh material shall be noncombustible.

3. The vent and mesh material shall be corrosion resistant.

504.10.3 Vent locations. Gable-end and dormer vents shall be located not less than 10 feet (3048 mm) from lot lines. Underfloor ventilation openings shall be located as close to grade as practical.

Accessory buildings and miscellaneous structures that have the potential to pose a significant exterior fire exposure hazard during wildfires shall be constructed to conform to the ignition-resistance require- ments of this section.

504.11.1 Applicability . Sections 504.11.2 through 504.11.6 apply to buildings accessory to an applicable building on the same lot, and attached or detached miscellaneous structures that require a building permit, including but not limited to trellises, arbors, patio covers, gazebos and similar structures.

Exceptions: 1. Decks shall comply with the requirements of Section 504.7.3. 2. Awnings and canopies shall comply with the requirements of Section 3105 of the California Building Code.

504.11.2 Miscellaneous structures and accessory buildings within 3 feet. Miscellaneous structures that require a permit, and accessory buildings of any size, when separated from an applicable building on the same lot by a distance of less than 3 feet (914 mm), shall be constructed of noncombustible materials or ignition-resistant building materials as described in Section 503.2.4.

504.11.3 Accessory buildings greater than 120 square feet, located 3 feet or more but less than 50 feet. Accessory buildings that are greater than 120 square feet (11.15 m2) in size and separated from an applicable building on the same lot by a distance of 3 feet (914 mm) or more but less than 50 feet (15 240 mm) shall be constructed of noncombustible materials or of ignition-resistant building materials as described in Section 503.2.4.

504.11.4 Accessory buildings 120 square feet or less, located 3 feet or more but less than 50 feet. Where required by the code offi- cial, accessory buildings 120 square feet (11.15 m2) or less and separated from an applicable building on the same lot by a distance of 3 feet (914 mm) or more but less than 50 feet (15 240 mm) shall be constructed of noncombustible materials or of ignition-resistant building materials as described in Section 503.2.4.

504.11.5 Miscellaneous structures located 3 feet or more but less than 50 feet. Where required by the code official, miscellaneous structures that require a permit and are separated from an applicable building on the same lot by a distance of 3 feet (914 mm) or more but less than 50 feet (15 240 mm) shall be constructed of noncombustible materials or of ignition-resistant building materials as described in Section 503.2.4.

ated 3 feet or more but less than 50 feet.**_ Where required by the code official, miscellaneous structures that require a permit and are separated from an applicable building on the same lot by a distance of 3 feet (914 mm) or more but less than 50 feet (15 240 mm) shall be constructed of noncombustible materials or of ignition-resistant building materials as described in Section 503.2.4.

504.11.6 Roof construction. Roof assemblies and roof coverings of accessory buildings required to be constructed entirely of noncombustible materials or of ignition-resistant building materials shall comply with Sections 504.2 and 504.2.1. Roofs shall have a roofing assembly installed in accordance with its listing and the manufacturer’s installation instructions. Roof assemblies in Fire Hazard Severity Zones shall comply with a Class A fire classification when tested in accordance with ASTM E108 or UL 790.