CRC · California Residential Code
What standards govern roof-assembly fire tests and combustible roofing classification?
Summary: If you install insulation above the roof deck, the California Residential Code (§ R906.1) requires that the insulation be covered by an approved roof covering and that the completed assembly comply with NFPA 276 or UL 1256; when a roof classification (Class A/B/C) is required the assembly must be tested and listed per ASTM E108 or UL 790.
Last reviewed: July 6, 2026
What the code requires — plain English (controlling §)
- § R906.1 — If you install above‑deck thermal insulation, it must be covered by an approved roof covering and the assembly must comply with either NFPA 276 or UL 1256.
- More broadly, roof assemblies required to be classified Class A, B or C must be tested and listed in accordance with ASTM E108 or UL 790, and the roof assembly must be identified to its class by an approved testing/listing agency (§ R902.1).
If you put insulation above the roof deck, you can’t leave it exposed — cover it with an approved roof covering, and the finished assembly must meet NFPA 276 or UL 1256 per § R906.1.
Requirements in detail
Scope and the controlling sentence
- § R906.1 (Residential Code) is specific to above‑deck thermal insulation: when that insulation is installed it “shall be covered with an approved roof covering and shall comply with NFPA 276 or UL 1256.”
How this fits with roof‑assembly fire classification
- The roof‑classification framework appears in § R902.1: when Class A, B or C classification is required, the roof assembly (deck + covering ± underlayment, insulation, components) must be tested in accordance with ASTM E108 or UL 790 and listed/identified as to class by an approved testing agency.
- The California Building Code mirrors and expands this: CBC §1505.1 states Class A/B/C assemblies “shall be tested in accordance with ASTM E108 or UL 790.”
When NFPA 276 / UL 1256 apply (what § R906.1 actually requires)
- The specific obligation under § R906.1 is twofold:
- Cover the above‑deck thermal insulation with an approved roof covering (do not leave it exposed), and
- Ensure the assembly (as installed) complies with NFPA 276 or UL 1256.
Decision‑relevant dimensions and values (quick reference)
| Decision question | Required value / threshold | Code Reference |
|---|---|---|
| If above‑deck thermal insulation is installed, must it be covered and tested? | Yes — must be covered with an approved roof covering and comply with NFPA 276 or UL 1256. | § R906.1 |
| Which tests govern roof‑assembly fire classification? | ASTM E108 or UL 790 for Class A/B/C listing and identification. | § R902.1 |
| When is a classified roof required because of lot line proximity? | Where roof edge is less than 3 feet (914 mm) from a lot line (classified roofing required). | § R902.1 |
| When is at least Class C required for reroofs / replacements? | If > 50 percent of total roof area is replaced in one year (or for new structures / many reroofs). | § R902.1 |
| Copper sheet exception for Class A (weight) | Minimum 16 ounces per square foot (≈ 4.882 kg/m²) copper sheets installed over combustible decks are considered Class A. | § R902.1 (exceptions) |
| Foam plastics in roof assemblies | Permitted only when the assembly is Class A/B/C where tested in accordance with ASTM E108 or UL 790. | CBC §2603.6 |
Practical implications of the standards named in § R906.1
- NFPA 276 and UL 1256 are the specific fire‑test/acceptance standards the CRC requires for above‑deck thermal insulation assemblies; compliance is achieved when the assembly tested to those standards meets acceptance criteria and the product/listing is used per listing. § R906.1 must be the starting point for submittals and listings involving above‑deck insulation.
- Where a roof assembly must also meet a Class (A/B/C) requirement (see § R902.1), the owner/installer must use assemblies/listings tested to ASTM E108 or UL 790 and ensure the whole assembly (including the insulation/underlayment/cover) is the listed assembly being used.
Exceptions & special cases
- § R902.1 lists several exceptions where specific coverings are treated as Class A without the ASTM E108/UL 790 test, for example brick, masonry, exposed concrete decks, or metal or tile installed on noncombustible decks, plus 16 oz/sq ft copper over combustible decks. Use those exceptions only when the listed conditions are met.
- Wildland/Fire Hazard Severity / WUI areas have additional or different requirements — roofing there must also comply with the California Wildland‑Urban Interface Code (see WUI §504.2 and related) where Class A may be explicitly required and additional underlayment/airspace rules apply.
- Foam plastics: if foam plastic insulation is part of the roof assembly, the assembly must still achieve a Class A/B/C rating by ASTM E108 or UL 790 before use in roof assemblies (CBC §2603.6).
Common mistakes
- Assuming § R906.1 is a mere material‑specification for insulation — it is an assembly requirement: above‑deck insulation must be covered by an approved roof covering and the assembly must comply with NFPA 276 or UL 1256, not just that the insulation board meets a material ASTM.
- Using an assembly listing for a roof covering without confirming the exact components (underlayment, insulation type and location, deck type) match the listing. The code requires that the roof assembly be listed and identified as to class by an approved testing agency when classification is required.
- Treating ASTM E108/UL 790 as optional: when a Class designation is required by the code (lot line proximity, reroof thresholds, local designation), ASTM E108 or UL 790 testing/listing is the specified acceptance route.
- Forgetting WUI / Fire Hazard Severity Zone overlay requirements — these areas can require stricter assembly testing and underlayment/airspace control (see WUI Code §504.x).
Worked example — concrete scenario
Scenario: You are reroofing a house. You will install 2 layers of 1.5‑inch above‑deck polyiso insulation over a combustible plywood roof deck, then install a membrane roof system.
Because you are installing above‑deck thermal insulation, § R906.1 requires the insulation be covered with an approved roof covering and the finished assembly must comply with NFPA 276 or UL 1256. That means either:
- Use a roof assembly/listing that was tested as an assembly including that polyiso above the deck to NFPA 276 or UL 1256; or
- Have the completed assembly validated/listed by an approved testing/listing agency to one of those standards before accepting it for code compliance.
Check whether the roof needs a Class rating: if you are replacing > 50% of the roof area in the last 12 months, § R902.1 requires the covering be at least Class C. If the roof edge is < 3 feet from a lot line, a classified roof (A/B/C) is required as well — in either case you must use an assembly listed to ASTM E108 or UL 790 (or rely on an exception in § R902.1). So:
- If you are replacing 60% of the roof, you must select a membrane/assembly that is Class C or better and listed per ASTM E108 or UL 790.
If your selected assembly contains foam plastic insulation (polyiso is foam plastic), confirm CBC §2603.6 — the assembly is permitted only if it is Class A/B/C as tested to ASTM E108 or UL 790. Thus you must confirm the assembly listing specifically includes the foam thickness and configuration you plan to use.
Bottom line for this scenario: Don’t install above‑deck polyiso as an exposed layer. Use a listed assembly (insulation + deck + membrane + underlayment) that either is shown to comply with NFPA 276 or UL 1256 per § R906.1, and if a roof classification is required, ensure the assembly is listed to ASTM E108 or UL 790 matching the required Class (A/B/C).
Related provisions (quick links to code sections)
- § R906.1 — Above‑deck thermal insulation: cover and comply with NFPA 276 or UL 1256.
- § R902.1 — Roof assemblies: Class A/B/C testing and ASTM E108 / UL 790 requirement; lot‑line and replacement thresholds.
- § R905 — Requirements for roof coverings (material standards and installation rules referenced elsewhere in Chapter 9).
- California Building Code §1505.1 — Roof fire classifications (echoes E108 / UL 790 testing requirements).
- CBC §2603.6 — Foam plastics in roofing: permitted only when the roof assembly is Class A/B/C as tested to ASTM E108 or UL 790.
- Wildland‑Urban Interface Code §504.2 — Additional Class A requirements and underlayment/airspace rules in WUI areas.
Code references
Grounded in the retrieved California Residential Code — click a citation to read the verbatim passage:
CRC § 4.882 High relevance — show source text
Chapter 9 also provides requirements for roof drainage, flashing, above-deck thermal insulation, rooftop-mounted photovoltaic systems and recovering or replacing an existing roof covering.
SECTION R901—GENERAL
R901.1 Scope. The provisions of this chapter shall govern the design, materials, construction and quality of roof assemblies.
SECTION R902—FIRE CLASSIFICATION
R902.1 Roof assemblies. Roof decks shall be covered with materials as set forth in Section R904 or with roof coverings as set forth in Section R905. A minimum Class A, B or C roofing shall be installed in areas designated by this section or where the edge of the roof deck is less than 3 feet (914 mm) from a lot line. Where Class A, B or C roof assemblies are required, they shall be tested in accordance with ASTM E108 or UL 790. Where required, the roof assembly shall be listed and identified as to class by an approved testing agency.
Exceptions:
Class A roof assemblies include those with coverings of brick, masonry and exposed concrete roof deck.
Class A roof assemblies include ferrous or copper shingles or sheets, metal sheets and shingles, clay or concrete roof tile, or slate installed on noncombustible roof decks or ferrous, copper or metal sheets installed without a roof deck on noncombustible framing.
Class A roof assemblies include minimum 16 ounces per square foot (4.882 kg/m [2] ) copper sheets installed over combustible roof decks.
Class A roof assemblies include slate installed over underlayment over ASTM D226, Type II underlayment over combustible decks.
R902.1.1 Roofing requirements within Fire Hazard Severity Zones or in Wildland-Urban Interface (WUI) area. Roofing require- ments for structures located within Fire Hazard Severity Zones or in a Wildland-Urban Interface (WUI) area shall also comply with Part 7, California Wildland-Urban Interface Code.
R902.1.2 Roof coverings in all other areas other than Fire Hazard Severity Zones or a Wildland-Urban Interface (WUI) area. The entire roof covering of every existing structure where more than 50 percent of the total roof area is replaced within any one-year period, the entire roof covering of every new structure, and any roof covering applied in the alteration, repair or replacement of the roof of every existing structure, shall be a fire-retardant roof covering that is at least Class C fire classification.
R902.2 Fire-retardant-treated shingles and shakes. Fire-retardant-treated wood shakes and shingles are wood shakes and shin- gles complying with UBC Standard 15-3 or 15-4 which are impregnated by the full-cell vacuum-pressure process with fire-retardant chemicals, and which have been qualified by UBC Standard 15-2 or ASTM E108 or UL 790 for use on Class A, B or C roofs. Fire-retardant- treated wood shakes and shingles shall comply with ICC-ES EG107 and with the weathering requirements contained in Health and Safety Code Section 13132.7 (j). Each bundle shall bear labels from an ICBO accredited quality control agency identifying their roof-covering classification and indicating their compliance with ICC-ES EG107 and with the weathering requirements contained in Health and Safety Code Section 13132.7 (j).
CRC § 4.1 High relevance — show source text
1|||X||||||||||||||||||||| |R902.1 - R902.4|||X||||||||||||||||||||| |R903.4.1||||X|||||||||||||||||||| |R904.1 - R904.4|||X||||||||||||||||||||| |R905.15||||X|||||||||||||||||||| |R905.16||||X|||||||||||||||||||| |R907.1||||X|||||||||||||||||||| |R907.2 – R907.5|||X||||||||||||||||||||| |R909|||X|||||||||||||||||||||
The state agency does not adopt sections identified with the following symbol: †
2025 CALIFORNIA RESIDENTIAL CODE 9-1
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
9-2 2025 CALIFORNIA RESIDENTIAL CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
9 ROOF ASSEMBLIES
User notes:
About this chapter: Chapter 9 addresses the design and construction of roof assemblies. A roof assembly includes the roof deck, substrate or thermal barrier, insulation, vapor retarder and roof covering. This chapter provides the requirement for wind resistance of roof coverings. The types of roof covering materials and installation addressed by Chapter 9 are: asphalt shingles, clay and concrete tile, metal roof shingles, mineral-surfaced roll roofing, slate and slate-type shingles, wood shakes and shingles, built-up roofs, metal roof panels, modified bitumen roofing, thermoset and thermoplastic single-ply roofing, sprayed polyurethane foam roofing, liquid applied coatings and building-integrated photovoltaic (BIPV) roof coverings. Chapter 9 also provides requirements for roof drainage, flashing, above-deck thermal insulation, rooftop-mounted photovoltaic systems and recovering or replacing an existing roof covering.
SECTION R901—GENERAL
R901.1 Scope. The provisions of this chapter shall govern the design, materials, construction and quality of roof assemblies.
SECTION R902—FIRE CLASSIFICATION
R902.1 Roof assemblies. Roof decks shall be covered with materials as set forth in Section R904 or with roof coverings as set forth in Section R905. A minimum Class A, B or C roofing shall be installed in areas designated by this section or where the edge of the roof deck is less than 3 feet (914 mm) from a lot line. Where Class A, B or C roof assemblies are required, they shall be tested in accordance with ASTM E108 or UL 790. Where required, the roof assembly shall be listed and identified as to class by an approved testing agency.
Exceptions:
Class A roof assemblies include those with coverings of brick, masonry and exposed concrete roof deck.
Class A roof assemblies include ferrous or copper shingles or sheets, metal sheets and shingles, clay or concrete roof tile, or slate installed on noncombustible roof decks or ferrous, copper or metal sheets installed without a roof deck on noncombustible framing.
Class A roof assemblies include minimum 16 ounces per square foot (4.882 kg/m [2] ) copper sheets installed over combustible roof decks.
Class A roof assemblies include slate installed over underlayment over ASTM D226, Type II underlayment over combustible decks.
CRC § 1505.1.1 High relevance — show source text
ROOF ASSEMBLIES AND ROOFTOP STRUCTURES
1505.1.1 Roofing requirements within Fire Hazard Severity Zones or in the Wildland-Urban Interface (WUI). Roofing require- ments for structures located within Fire Hazard Severity Zones or in the Wildland-Urban Interface (WUI) shall also comply with Section 705A.
1505.1.2 Roof coverings within all other areas other than Fire Hazard Severity Zones or a Wildland-Urban Interface (WUI). The entire roof covering of every existing structure where more than 50 percent of the total roof area is replaced within any one-year period, the entire roof covering of every new structure, and any roof covering applied in the alteration, repair or replacement of the roof of every existing structure, shall be a fire-retardant roof covering that is at least Class C fire classification.
[BF] 1505.2 Class A roof assemblies. Class A roof assemblies are those that are effective against severe fire test exposure. Class A roof assemblies and roof coverings shall be listed and identified as Class A by an approved testing agency. Class A roof assemblies shall be permitted for use in buildings or structures of all types of construction.
Exceptions:
Class A roof assemblies include those with coverings of brick, masonry or an exposed concrete roof deck.
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.
Class A roof assemblies include minimum 16 ounce per square foot (0.0416 kg/m [2] ) copper sheets installed over combustible decks.
Class A roof assemblies include slate installed over ASTM D226, Type II or ASTM D4869, Type IV underlayment over combustible decks.
[BF] 1505.3 Class B roof assemblies. Class B roof assemblies are those that are effective against moderate fire-test exposure. Class B roof assemblies and roof coverings shall be listed and identified as Class B by an approved testing agency.
[BF] 1505.4 Class C roof assemblies. Class C roof assemblies are those that are effective against light fire-test exposure. Class C roof assemblies and roof coverings shall be listed and identified as Class C by an approved testing agency.
[BF] 1505.5 Nonclassified roofing. Nonclassified roofing is approved material that is not listed as a Class A, B or C roof covering assembly or roof covering.
[BF] 1505.6 Fire-retardant-treated wood shingles and shakes. Fire-retardant-treated wood shakes and shingles are wood shakes and shingles complying with UBC Standard 15-3 or 15-4 which are impregnated by the full-cell vacuum-pressure process with fire-retar- dant chemicals, and which have been qualified by UBC Standard 15-2 or ASTM E108 or UL 790 for use on Class A, B or C roofs.
Fire-retardant-treated wood shakes and shingles shall comply with ICC-ES EG107 and with the weathering requirements contained in Health and Safety Code Section 13132.7(j). Each bundle shall bear labels from an ICC accredited quality control agency identifying their roof-covering classification and indicating their compliance with ICC-ES EG107 and with the weathering requirements contained in Health and Safety Code Section 13132.7(j).
CRC § 1505.3 High relevance — show source text
- Class A roof assemblies include slate installed over ASTM D226, Type II or ASTM D4869, Type IV underlayment over combustible decks.
[BF] 1505.3 Class B roof assemblies. Class B roof assemblies are those that are effective against moderate fire-test exposure. Class B roof assemblies and roof coverings shall be listed and identified as Class B by an approved testing agency.
[BF] 1505.4 Class C roof assemblies. Class C roof assemblies are those that are effective against light fire-test exposure. Class C roof assemblies and roof coverings shall be listed and identified as Class C by an approved testing agency.
[BF] 1505.5 Nonclassified roofing. Nonclassified roofing is approved material that is not listed as a Class A, B or C roof covering assembly or roof covering.
[BF] 1505.6 Fire-retardant-treated wood shingles and shakes. Fire-retardant-treated wood shakes and shingles are wood shakes and shingles complying with UBC Standard 15-3 or 15-4 which are impregnated by the full-cell vacuum-pressure process with fire-retar- dant chemicals, and which have been qualified by UBC Standard 15-2 or ASTM E108 or UL 790 for use on Class A, B or C roofs.
Fire-retardant-treated wood shakes and shingles shall comply with ICC-ES EG107 and with the weathering requirements contained in Health and Safety Code Section 13132.7(j). Each bundle shall bear labels from an ICC accredited quality control agency identifying their roof-covering classification and indicating their compliance with ICC-ES EG107 and with the weathering requirements contained in Health and Safety Code Section 13132.7(j).
Health and Safety Code Section 13132.7(j). No wood roof covering materials shall be sold or applied in this state unless both of the following conditions are met: (1) The materials have been approved and listed by the State Fire Marshal as complying with the requirements of this section. (2) The materials have passed at least five years of the 10-year natural weathering test. The 10-year natural weathering test required by this subdivision shall be conducted in accordance with standard 15-2 of the 1994 edition of the Uniform Building Code at a testing facility recognized by the State Fire Marshal.
[BF] 1505.7 Special purpose roofs. Special purpose wood shingle or wood shake roofing shall conform to the grading and application requirements of Section 1507.8 or 1507.9. In addition, an underlayment of [5] / 8 -inch (15.9 mm) Type X water-resistant gypsum backing board or gypsum sheathing shall be placed under minimum nominal [1] / 2 -inch-thick (12.7 mm) wood structural panel solid sheathing or 1-inch (25 mm) nominal spaced sheathing.
[BF] 1505.8 Building-integrated photovoltaic (BIPV) systems. BIPV products installed as the roof covering shall be tested, listed and labeled for fire classification in accordance with Section 1505.1.
[BF] 1505.9 Rooftop mounted photovoltaic (PV) panel systems. Rooftop mounted photovoltaic (PV) panel systems shall be tested, listed and identified with a fire classification in accordance with UL 2703. Listed systems shall be installed in accordance with the manufacturer’s installation instructions and their listing. The fire classification shall comply with Table 1505.1 based on the type of construction of the building.
CRC § 503.2.5 High relevance — show source text
503.2.5 Surface treatment protection. Use of paints, coatings, stains or other surface treatments are not an approved method of protection as required in this chapter.
503.3 Standards of quality. Building material, systems, assemblies and methods of construction shall be tested in accordance with the standards specified in Chapter 5.
503.3.1 Qualification by testing. Material and material assemblies tested in accordance with the requirements of Section 503 shall be accepted for use when the results and conditions of those tests are met. Product evaluation testing of material and material assemblies shall be approved or listed by the State Fire Marshal or identified in a current report issued by an approved agency.
503.3.2 Approved agency. Product evaluation testing shall be performed by an approved agency in accordance with Section 1703 of the California Building Code. The scope of accreditation for the approved agency shall include building product compliance with this code.
503.3.3 Labeling. Material and material assemblies tested in accordance with the referenced standards shall bear an identification label showing the fire test results. That identification label shall be issued by a testing and/or inspecting agency approved by the State Fire Marshal.
1. Identification mark of the approved testing and/or inspecting agency.
2. Contact and identification information of the manufacturer.
3. Model number or identification of the product or material. 4. Pretest weathering specified in this chapter. 5. Compliance standard as described under Chapter 7.
503.3.4 Fire-retardant-treated wood shingles and shakes. Fire-retardant-treated wood shingles and shakes shall be approved and listed by the State Fire Marshal in accordance with Section 208(c), Title 19 California Code of Regulations.
� SECTION 504—IGNITION-RESISTANT CONSTRUCTION
504.1 General. Ignition-resistant construction shall be in accordance with Sections 504.2 through 504.11.6 .
5-4 2025 CALIFORNIA WILDLAND-URBAN INTERFACE CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
SPECIAL BUILDING CONSTRUCTION REGULATIONS
504.2 Roof assembly. 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:
- Roof assemblies with coverings of brick, masonry or an exposed concrete roof deck.
- 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.
- 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.
CRC § 504.1 High relevance — show source text
� SECTION 504—IGNITION-RESISTANT CONSTRUCTION
504.1 General. Ignition-resistant construction shall be in accordance with Sections 504.2 through 504.11.6 .
5-4 2025 CALIFORNIA WILDLAND-URBAN INTERFACE CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
SPECIAL BUILDING CONSTRUCTION REGULATIONS
504.2 Roof assembly. 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:
- Roof assemblies with coverings of brick, masonry or an exposed concrete roof deck.
- 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.
- 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.
CRC § 803.5.1 High relevance — show source text
803.5.1, 803.5.1.1
268—22: Standard Test Method for Determining Ignitability of Exterior Wall Assemblies Using a Radiant Heat Energy Source
1405.1.1.1, 1405.1.1.1.1, 1405.1.1.1.2, 2603.5.7
275—22: Standard Method of Fire Tests for the Evaluation of Thermal Barriers
508.4.4.1, 509.4.1.1, 1406.10.2, 1408.10.2, 2603.4
276—23: Standard Method of Fire Test for Determining the Heat Release Rate of Roofing Assemblies with Combustible Above- Deck Roofing Components
1508.1, 2603.3, 2603.4.1.5
285—23: Standard Fire Test Method for Evaluation of Fire Propagation Characteristics of Exterior Wall Assemblies Containing Combustible Components
718.2.6, 1402.6, 1406.10.3, 1408.10.4, 1511.6.2, 2603.5.5
286— 24 : Standard Methods of Fire Tests for Evaluating Contribution of Wall and Ceiling Interior Finish to Room Fire Growth
402.6.4.4, 424.2, 803.1.1, 803.1.1.1, 803.11, 803.12, 803.13, 1406.10.2, 1408.10.3, 2603.7, 2603.9, 2604.2.4, 2614.4, 3105.3
288—22: Standard Methods of Fire Tests of Horizontal Fire Door Assemblies Installed in Horizontal Fire Resistance-Rated Assemblies
712.1.13.1
289—23: Standard Method of Fire Test for Individual Fuel Packages
402.6.2, 402.6.4.5, 424.2, 806.4
409—22: Standard on Aircraft Hangars 412.3.6, Table 412.3.6, 412.3.6.1, 412.5.5
418— 24 : Standard for Heliports
412.7.4
484—22: Standard for Combustible Metals
426.1
502—20: Standard for Road Tunnels, Bridges, and Other Limited Access Highways
429
652—19: Standard on the Fundamentals of Combustible Dust
426.1
654—20: Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing, and Handling of Combustible Particulate Solids
426.1
35-38 2025 CALIFORNIA BUILDING CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
REFERENCED STANDARDS
655—19: Standard for the Prevention of Sulfur Fires and Explosions
426.1
664—20: Standard for the Prevention of Fires and Explosions in Wood Processing and Woodworking Facilities
426.1
701—23: Standard Methods of Fire Tests for Flame Propagation of Textiles and Films
CRC § 504.2.1.1 High relevance — show source text
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.
504.3 Protection of enclosed eaves. 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.
CRC § 12-7 High relevance — show source text
Individual thermocouple readings shall not exceed or fall below the standard time-temperature curve by more than 15 percent. (d) Furnace correction. When the indicated resistance period is [1] / 2 hour or over, determined by the average or maximum temperature rise on the unexposed surface or within the test sample, or by failure under load, a correction shall be applied for variation of the furnace exposure from that prescribed, where it will affect the classification, by multiplying the indicated period by twothirds of the difference in area between the curve of average furnace temperature and the standard curve for the first three-fourths of the period and dividing the product by the area between the standard curve and a base line of 60°F (20°C) for the same part of the indicated period, the latter area increased by 54 Fahr-hour or 30 Cent-hour (3240 Fahr-minutes or 1800 Cent-minutes) to compensate for the thermal lag of the furnace thermocouples during the first part of the test. For fire exposure in the test higher than standard, the indicated resistance period shall be increased by the amount of the correction and be similarly decreased for fire exposure below standard.
Note: The correction can be expressed by the following formula:
C = --------------------------21 A ( – AS ) 3 AS ( + L )
where:
C = correction in the same units as 1
1 = indicated fire endurance period
A = area under the curve of indicated average furnace temperature for the first three-fourths of the indicated period
AS = area under the standard furnace curve for the same part of the indicated period
L = lag correction in the same units as A and AS (54 Fahr-hour or 30 Cent-hour (3240 Fahr-minutes or 1800 Cent-minutes)
(e) Furnace pressure. The pressure in the furnace chamber during the fire test shall be maintained as nearly equal to atmospheric pressure as possible. Horizontal furnaces may be operated at a slight negative pressure sufficient to reduce haze permitting visual observation. Furnace stacks shall be equipped with dampers to facilitate maintenance of furnace pressure.
CORRELATION
Sec. 12-7-305. Tests of specific assemblies of materials shall be conducted for correlation (or correlation factor) of furnace exposure by comparison with tests of identical assemblies and materials conducted in furnaces of “Approved Listing Agencies” which furnaces are deemed as conforming to the design and operating requirements of this standard.
Correlation tests of wall furnaces shall include tests of two assemblies, one combustible and one noncombustible.
Correlation tests of horizontal furnaces dependent on intended test specimens shall include at least one test for each type of assembly such as combustible ceiling-floor assembly, noncombustible assembly having a high thermal capacity floor for heat dissipation, noncombustible assembly having an insulating concrete floor or other type of design.
Comparison of test results shall provide evidence of equivalent exposure based on transmitted temperatures on the unexposed side, on structural framing members, on the underside of floor or roof decks, and in the plenum space.
28 2025 CALIFORNIA REFERENCED STANDARDS CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
FIRE-RESISTIVE STANDARDS
2025 CALIFORNIA REFERENCED STANDARDS CODE 29
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
30 2025 CALIFORNIA REFERENCED STANDARDS CODE
CRC § 5.3. High relevance — show source text
2025 CALIFORNIA REFERENCED STANDARDS CODE 43
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
MATERIALS AND CONSTRUCTION METHODS FOR EXTERIOR WILDFIRE EXPOSURE
5.3. Continued combustion. If penetration does not occur, continue observation for an additional 30 minutes or until all combustion has ceased.
Note: An infrared thermometer has been found to be useful to detect the increase of temperature on the back side of the eaves and as an aid to identify the areas of potential combustion. 6. Observations. Note the time, location and nature of flame penetration.
12-7A-3.9 Report. The report shall include a description of the eaves material, details of the construction of the eaves, moisture content of the framing and wood-based soffit elements as applicable, and point of flame penetration. Provide details on the time and reasons for early termination of the test.
12-7A-3.10 Conditions of Acceptance. Should one of the three replicates fail to meet the Conditions of Acceptance, three additional tests may be run. All of the additional tests must meet the Conditions of Acceptance.
- Absence of flame penetration of the eaves or horizontal projection assembly at any time.
- Absence of structural failure of the eaves or horizontal projection subassembly at any time.
- Absence of sustained combustion of any kind at the conclusion of the 40-minute test.
FIGURE 1 — EAVES TEST ASSEMBLY
44 2025 CALIFORNIA REFERENCED STANDARDS CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
MATERIALS AND CONSTRUCTION METHODS FOR EXTERIOR WILDFIRE EXPOSURE
DECKING
SFM STANDARD 12-7A-4
12-7A-4.1 Application. The minimum design, construction and performance standards set forth herein for unloaded decks are those deemed necessary to establish conformance to the provisions of these regulations. Materials and assemblies that meet the performance criteria of this standard are acceptable for use as defined in California Building Standards Code.
12-7A-4.2 Scope. This standard evaluates the performance of decks (or other horizontal ancillary structures in close proximity to primary structures) when exposed to direct flames and brands. The under-deck flame exposure test is intended to determine the heat release rate (HRR) and degradation modes of deck or other horizontal boards when exposed to a burner flame simulating combustibles beneath a deck. The burning brand exposure test is intended to determine the degradation modes of deck or other horizontal boards when exposed to a burning brand on the upper surface.
12-7A-4.3 Referenced document.
ASTM D4444, Test Methods for Use and Calibration of Hand-Held Moisture Meters.
ASTM E108, Test Methods for Fire Tests of Roof Coverings.
California Building Code, Chapter 7A.
UL 790, Standard Test Methods for Fire Tests of Roof Coverings.
12-7A-4.4 Definitions.
- Deck boards. Horizontal members that constitute the exposed surface of the ancillary structure.
- Deck surface area. The test specimen area defined by the overall specimen length and width after assembly.
- Heat release rate. The net rate of energy release as measured by oxygen depletion calorimetry.
**12-7A-4.5 Test assembly.
CRC § 9-4 Medium relevance — show source text
R904 Materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-4
R905 Requirements for Roof Coverings . . . . . . . . . . . . . . . . 9-4
R906 Roof Insulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-19
R907 Rooftop-Mounted Photovoltaic Panel Systems . . . 9-19
R908 Reroofing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-19
R909 Roof Coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-20
CHAPTER 10 CHIMNEYS AND FIREPLACES . . . . . . . . . . . .10-3
R1001 Masonry Fireplaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-3
R1002 Masonry Heaters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-6
R1003 Masonry Chimneys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-7
R1004 Factory-Built Fireplaces. . . . . . . . . . . . . . . . . . . . . . . . 10-12
R1005 Factory-Built Chimneys . . . . . . . . . . . . . . . . . . . . . . . . 10-12
R1006 Exterior Air Supply. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-12
Part IV—Energy Conservation. . . . . . . . . . . . . . . . . . . . . . . .11-1
Part V—Mechanical. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12-1
Part VI—Fuel Gas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24-1
Part VII—Plumbing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25-1
Part VIII—Electrical. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34-1
Part IX— Referenced Standards . . . . . . . . . . . . . . . . . . . . . .44-3
CHAPTER 44 REFERENCED STANDARDS . . . . . . . . . . . . . .44-3
CRC § 8-3 Medium relevance — show source text
R802 Wood Roof Framing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3
R803 Roof Sheathing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-30
R804 Cold-Formed Steel Roof Framing . . . . . . . . . . . . . . . 8-31
R805 Ceiling Finishes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-44
R806 Roof Ventilation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-44
R807 Attic Access. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-46
CHAPTER 9 ROOF ASSEMBLIES . . . . . . . . . . . . . . . . . . . . . .9-3
R901 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-3
R902 Fire Classification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-3
R903 Weather Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-4
R904 Materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-4
R905 Requirements for Roof Coverings . . . . . . . . . . . . . . . . 9-4
R906 Roof Insulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-19
R907 Rooftop-Mounted Photovoltaic Panel Systems . . . 9-19
R908 Reroofing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-19
R909 Roof Coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-20
CHAPTER 10 CHIMNEYS AND FIREPLACES . . . . . . . . . . . .10-3
R1001 Masonry Fireplaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-3
R1002 Masonry Heaters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-6
R1003 Masonry Chimneys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-7
CRC § 1.0 High relevance — show source text
Extrapolation is not permitted.
c. Basic wind speed,V, and wind exposure shall be determined in accordance with Section 1609.
d. Where the minimum required parapet height is indicated to be 2 inches (51 mm), a gravel stop shall be permitted and shall extend not less than 2 inches (51 mm) from the roof
surface and not less than the height of the aggregate.
e. The tabulated values apply only to conditions where the topographic factor (Kzt) determined in accordance with Chapter 26 of ASCE 7 is 1.0 or where_Kzt_ is incorporated in the
basic wind speed in Section 1609.
f. For Exposure D, add 8 inches (203 mm) to the parapet height required for Exposure C and the parapet height shall not be less than 12 inches (305 mm).|For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 mile per hour = 0.447 m/s.
a. Parapet height is measured vertically from the top surface of the coping down to the surface of the roof covering in the field of the roof adjacent to the parapet and outbound
of any cant strip.
b. Interpolation shall be permitted for wind speed, mean roof height and parapet height. Extrapolation is not permitted.
c. Basic wind speed,V, and wind exposure shall be determined in accordance with Section 1609.
d. Where the minimum required parapet height is indicated to be 2 inches (51 mm), a gravel stop shall be permitted and shall extend not less than 2 inches (51 mm) from the roof
surface and not less than the height of the aggregate.
e. The tabulated values apply only to conditions where the topographic factor (Kzt) determined in accordance with Chapter 26 of ASCE 7 is 1.0 or where_Kzt_ is incorporated in the
basic wind speed in Section 1609.
f. For Exposure D, add 8 inches (203 mm) to the parapet height required for Exposure C and the parapet height shall not be less than 12 inches (305 mm).|SECTION 1505—FIRE CLASSIFICATION
[BF] 1505.1 General. Fire classification of roof assemblies shall be in accordance with Section 1505. The minimum fire classification of roof assemblies installed on buildings shall comply with Table 1505.1 based on type of construction of the building. Class A, B and C roof assemblies and roof coverings required to be listed by this section shall be tested in accordance with ASTM E108 or UL 790. In addition, fire-retardant-treated woodroof coverings shall be tested in accordance with ASTM D2898; fire-retardant-treated shingles and shakes shall comply with Section 1505.6.
Exception: Skylights and sloped glazing that comply with Chapter 24 or Section 2610.
CRC § 2-50 Medium relevance — show source text
2-50 2025 CALIFORNIA BUILDING CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
DEFINITIONS
[BF] RESPONSIVE VAPOR RETARDER. A vapor retarder material complying with a vapor retarder class of Class I or II, but that also has a vapor permeance of 1 perm or greater in accordance with ASTM E96, water method (Procedure B).
[BE] RESTRICTED ENTRANCE. An entrance that is made available for common use on a controlled basis, but not public use, and that is not a service entrance.
[BG] RETRACTABLE AWNING. A retractable awning is a cover with a frame that retracts against a building or other structure to which it is entirely supported.
RETROFIT. [DSA-SS, DSA-SS/CC, OSHPD 1, 1R, 2, 4 & 5] The construction of any new element or system, or the alteration of any existing element or system required to bring an existing building, or portion thereof, conforming to earlier code requirements, into conformance with standards of the currently effective California Building Standards Code.
RISER. The upright part between two adjacent stair treads, between either an upper or lower landing and an adjacent stair tread, or between two adjacent landings.
[BS] RISK CATEGORY. A categorization of buildings and other structures for determination of flood, wind, snow, ice and earthquake loads based on the risk associated with unacceptable performance.
[BS] ROOF ASSEMBLY (For application to Chapter 15 only). A system designed to provide weather protection and resistance to design loads. The system consists of a roof covering and roof deck or a single component serving as both the roof covering and the roof deck. A roof assembly can include an underlayment, a thermal barrier, insulation or a vapor retarder.
[BS] ROOF COATING. A fluid-applied, adhered coating used for roof maintenance or roof repair, or as a component of a roof covering system or roof assembly.
[BS] ROOF COVERING. The covering applied to the roof deck for weather resistance, fire classification or appearance.
ROOF COVERING SYSTEM. See “Roof assembly.”
[BS] ROOF DECK. The flat or sloped surface constructed on top of the exterior walls of a building or other supports for the purpose of enclosing the story below, or sheltering an area, to protect it from the elements, not including its supporting members or vertical supports.
ROOF DRAINAGE, POSITIVE. See “Positive roof drainage.”
[BS] ROOF RECOVER. The process of installing an additional roof covering over a prepared existing roof covering without removing the existing roof covering.
[BS] ROOF REPAIR. Reconstruction or renewal of any part of an existing roof for the purposes of correcting damage or restoring predamage condition.
[BS] ROOF REPLACEMENT. The process of removing the existing roof covering, repairing any damaged substrate and installing a new roof covering.
[BG] ROOF VENTILATION. The natural or mechanical process of supplying conditioned or unconditioned air to, or removing such air from, attics, cathedral ceilings or other enclosed spaces over which a roof assembly is installed.
CRC § 1910.1000. Medium relevance — show source text
Class 2. An oxidizer that will cause a moderate increase in the burning rate of combustible materials with which it comes in contact.
Class 1. An oxidizer that does not moderately increase the burning rate of combustible materials.
OXIDIZING CRYOGENIC FLUID. An oxidizing gas in the cryogenic state.
OXIDIZING GAS. A gas that can support and accelerate combustion of other materials more than air does.
OZONE-GAS GENERATOR. Equipment which causes the production of ozone.
[BE] PANIC HARDWARE. A door-latching assembly incorporating a device that releases the latch upon the application of a force in the direction of egress travel. See also “Fire exit hardware.”
PASSIVE RF EMITTING DEVICE. A device that does not require an external AC or DC source of power for its operation, and does not provide amplification of the RF signal, including but not limited to coax, couplers, splitters and passive antennas.
PASS-THROUGH. An enclosure installed in a wall with a door on each side that allows chemicals, HPM, equipment, and parts to be transferred from one side of the wall to the other.
[A] PEER REVIEW. An independent and objective technical review conducted by an approved third party.
[BG] PENTHOUSE. An enclosed, unoccupied rooftop structure used for sheltering mechanical and electrical equipment, tanks, elevators and related machinery, and vertical shaft openings.
PERMANENT PORTABLE BUILDING. A portable building that is used to serve or house students and is certified as a permanent building on a new public school campus by the public school administration shall comply with the requirements of new campus buildings.
PERMISSIBLE EXPOSURE LIMIT (PEL). The maximum permitted 8-hour time-weighted-average concentration of an airborne contaminant. The exposure limits to be utilized are those published in DOL 29 CFR Part 1910.1000. The Recommended Exposure Limit (REL) concentrations published by the US National Institute for Occupational Safety and Health (NIOSH), Threshold Limit Value-Time Weighted Average (TLV-TWA) concentrations published by the American Conference of Governmental Industrial Hygienists (ACGIH), Workplace Environmental Exposure Level (WEEL) Guides published by the American Industrial Hygiene Association (AIHA), and other approved, consistent measures are allowed as surrogates for hazardous substances not listed in DOL 29 CFR Part 1910.1000.
[A] PERMIT. An official document or certificate issued by the fire code official that authorizes performance of a specified activity.
[A] PERSON. An individual, heirs, executors, administrators or assigns, and also includes a firm, partnership or corporation, its or their successors or assigns, or the agent of any of the aforesaid.
PERSONS WITH INTELLECTUAL DISABILITIES, PROFOUNDLY OR SEVERELY. Shall mean any persons with intellectual disabilities who is unable to evacuate a building unassisted during emergency conditions.
Note: The determination as to such incapacity shall be made by the Director of the State Department of Public Health or his or her designated representative pursuant to Health and Safety Code Section 13131.3.
[BG] PERSONAL CARE SERVICE. The care of persons who do not require medical care. Personal care involves responsibility for the safety of the persons while inside the building.
Frequently asked questions
What exactly does § R906.1 require for above‑deck insulation?
§ R906.1 requires that above‑deck thermal insulation be covered with an approved roof covering and that the completed assembly comply with NFPA 276 or UL 1256.
If my roof assembly is listed to UL 790, do I still need to worry about NFPA 276 / UL 1256?
If your situation is triggered by § R906.1 (above‑deck insulation), the code text specifically requires compliance with NFPA 276 or UL 1256 for that assembly; ASTM E108 / UL 790 are the specified tests for Class A/B/C roof coverings under § R902.1. Verify which listing/standard the specific assembly/listing covers and confirm it matches the governing §.
Who issues the acceptable listing or label for an assembly?
An approved testing/listing agency (an approved testing agency or State Fire Marshal acceptance where applicable) must list and identify the roof assembly as to class when a class is required; listings and labels must show the applicable test result and assembly configuration.
Does the WUI (Wildland‑Urban Interface) change these standards?
Yes — WUI and Fire Hazard Severity Zones may impose stricter roof requirements and specific underlayment or airspace controls; these areas must also comply with the California Wildland‑Urban Interface Code (see WUI §504.x).
If I only replace shingles (less than 50% of the roof), do I need a Class C assembly?
Per § R902.1, replacing more than 50 percent of roof area triggers the requirement; if you replace less than or equal to 50% and no other local condition triggers it, the Class C requirement in that paragraph does not automatically apply. Always check local enforcement agency rules.
More in California Residential Code
Ask about the CRC
Get cited, plain-English answers on the California Residential Code for your project — any code section, any scenario.
Start Free Trial