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Chapter 3 — BUILDING PLANNING

Section R337.4

California Residential Code (Title 24, Part 2.5) · 2022 edition · updated 2026-09-12 · California

Italicized text is a California amendment to the model code, as printed in the official publication.

IGNITION-RESISTANT CONSTRUCTION R337.4.1 General. The materials prescribed herein for ignition resistance shall conform to the requirements of Section R337. R337.4.2 Ignition-resistant materials. Ignition-resistant materials shall comply with one of the following:

1. The requirements in Section R337.4.3 or 2. One of the alternative methods in Section R337.4.4. R337.4.3 Conditions of acceptance for ignition-resis- tant materials . The material shall comply with the condi- tions of acceptance in Items 1 and 2 below or with the conditions of acceptance of ASTM E2768.

1. The material shall exhibit a listed flame spread index not exceeding 25 when tested in accordance with ASTM E84 or UL 723. 2. Additionally, the ASTM E84 or UL 723 test shall be continued for an additional 20-minute period, and the 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 test period.

conditions contained in the following standards, as applicable to the materials and the conditions of use.

R337.3.5.2.1 Fire-retardant-treated wood. Fire- retardant-treated wood shall be tested in accor- dance with ASTM D2898 (Method A), and the requirements of Section 2303.2 of the California Building Code.

R337.3.5.2.2 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.

R337.3.5.3 Surface treatment protection. The use of paints, coatings, stains or other surface treatments are not an approved method of protection as required in this section.

R337.3.6 Alternates for materials, design, tests and meth- ods of construction. The enforcing agency is permitted to modify the provisions of this chapter for site-specific con- ditions in accordance with Section 1.11.2.4. When required by the enforcing agency for the purposes of granting modifications, a fire protection plan shall be sub- mitted in accordance with the California Fire Code, Chapter 49.

R337.3.7 Standards of quality. The State Fire Marshal standards for exterior wildfire exposure protection listed below and as referenced in this chapter are located in the California Referenced Standards Code, Part 12 and Chapter 44 of this code.

SFM Standard 12-7A-1, Exterior Wall Siding and Sheathing. A fire resistance test standard consisting of a 150 kW intensity direct flame exposure for a 10 min- utes duration.

SFM Standard 12-7A-2, Exterior Windows. A fire resistance test standard consisting of a 150 kW inten- sity direct flame exposure for an 8-minute duration.

SFM Standard 12-7A-3, Horizontal Projection Under- side A fire resistance test standard consisting of a 300 kW intensity direct flame exposure for a 10 minute duration.

SFM Standard 12-7A-4, Decking. A two-part test con- sisting of a heat release rate (Part A) deck assembly combustion test with an under deck exposure of 80 kW intensity direct flame for a 3 minute duration, and a (Part B) sustained deck assembly combustion test con- sisting of a deck upper surface burning ember exposure with a 12 mph wind for 40 minutes using a 2.2 lb (1 kg) burning “Class A” size 12” × 12” × 2.25” (300 mm x 300 mm x 57 mm) roof test brand.

SFM Standard 12-7A-4A, Decking Alternate Method A. A heat release rate deck assembly combustion test with an under deck exposure of 80 kW intensity direct flame for a 3 minute duration.

ASTM D2898, Standard Practice for Accelerated Weathering of Fire-Retardant-Treated Wood for Fire Testing

Copyright © 2022 by, or licensed to, International Code Council, Inc. (ALL RIGHTS RESERVED); licensed to California Building Standards Commission pursuant to License Agreement. No further reproductions is authorized. Any unauthorized reproduction or distribution is a violation of the federal copyright act and the license agreement, and subject to civil and criminal penalties thereunder.

BUILDING PLANNING

R337.4.3.1 Fire testing of wood structural panels. Wood structural panels shall be tested with a ripped or cut longitudinal gap of 1 /8 inch (3.2 mm).

R337.4.4 Alternative methods for determining ignition- resistant material. Any one of the following shall be accepted as meeting the definition of ignition-resistant material:

1. Noncombustible material. Material that complies with the definition for noncombustible materials in Section R202. 2. Fire-retardant-treated wood. Fire-retardant-treated wood identified for exterior use that complies with the requirements of Section 2303.2 of the California Building Code. 3. Fire-retardant-treated wood shingles and shakes. Fire-retardant-treated wood shingles and shakes, as defined in Section 1505.6 of the California Building Code and listed by State Fire Marshal for use as “Class B” roof covering, shall be accepted as an Ignition-resistant wall covering material when installed over solid sheathing.

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▸Contents — California Residential Code (Title 24, Part 2.5)
California Residential Code (Title 24, Part 2.5)
  1. Chapter 2 — DEFINITIONS AND ABBREVIATIONS
  2. Appendix AF — RADON CONTROL
  3. Appendix AI — PRIVATE SEWAGE
  4. Appendix AJ — EXISTING
  5. Appendix AK — SOUND
  6. Appendix AO — AUTOMATIC
  7. Appendix AR — LIGHT STRAW-CLAY
  8. Appendix AS — STRAWBALE
  9. Appendix AU — COB CONSTRUCTION
  10. Appendix AV — BOARD
  11. Appendix AW — 3D-PRINTED BUILDING
  12. Chapter 1 — SCOPE AND APPLICATION
  13. ▸Chapter 3 — BUILDING PLANNING
    Overview
    1. Section R300
    2. Section R301
    3. Section R302
    4. Section R303
    5. Section R304
    6. Section R305
    7. Section R307
    8. Section R308
    9. Section R306
    10. Section R309
    11. Section R310
    12. Section R311
    13. Section R312
    14. Section R313
    15. Section R314
    16. Section R315
    17. Section R316
    18. Section R317
    19. Section R318
    20. Section R319
    21. Section R320
    22. Section R321
    23. Section R322
    24. Section R323
    25. Section R324
    26. Section R325
    27. Section R327
    28. Section R326
    29. Section R328
    30. Section R329
    31. Section R330
    32. Section R334
    33. Section R335
    34. Section R336
    35. Section R337
    36. Section R337.1
    37. Section R337.2
    38. Section R337.3
    39. Section R337.4
    40. Section R337.5
    41. Section R337.6
    42. Section R337.7
    43. Section R337.8
    44. Section R337.9
    45. Section R337.10
    46. Section R338
    47. Section R340
  14. Chapter 4 — FOUNDATIONS
  15. Chapter 5 — FLOORS
  16. Chapter 6 — WALL CONSTRUCTION
  17. Chapter 7 — WALL COVERING
  18. Chapter 8 — ROOF-CEILING CONSTRUCTION
  19. Chapter 9 — ROOF ASSEMBLIES
  20. Chapter 10 — CHIMNEYS AND FIREPLACES
  21. Chapter 44 — REFERENCED STANDARDS
  22. Appendix AH — PATIO COVERS
  23. Appendix AL — PERMIT FEES
  24. Appendix AQ — TINY HOUSES
  25. Appendix AT — SOLAR-READY PROVISIONS—DETACHED ONE- AND
  26. Appendix AX — SWIMMING POOL SAFETY ACT
  27. Appendix AY — AREAS PROTECTED BY THE FACILITIES
  28. Appendix AZ — EMERGENCY HOUSING

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