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Chapter 3 — BUILDING PLANNING

Section R337.7

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.

EXTERIOR COVERING R337.7.1 Scope. The provisions of this section shall gov- ern the materials and construction methods used to resist building ignition and/or safeguard against the intrusion of flames resulting from small ember and short-term direct flame contact exposure.

R337.7.2 General. The following exterior covering mate- rials and/or assemblies shall comply with this section:

1. Exterior wall coverings.

2. Exterior wall assemblies.

3-100 2022 CALIFORNIA RESIDENTIAL CODE

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

side, as tested in accordance with ASTM E119 or UL 263.

6. Assembly suitable for exterior fire exposure contain- ing one layer of 5 /8-inch (16 mm) Type X gypsum sheathing applied behind the exterior wall covering or cladding on the exterior side of the framing.

7. Assembly suitable for exterior fire exposure contain- ing any of the gypsum panel and sheathing products listed in the Gypsum Association Fire Resistance Design Manual as complying with a 1-hour fire- resistance rating, as tested in accordance with ASTM E119 or UL 263.

R337.7.4.1 Conditions of acceptance when tested in accordance with ASTM E2707. The ASTM E2707 test shall be conducted on a minimum of three test speci- mens, and the conditions of acceptance in Items 1 and 2 below shall be met. If any one of the three tests do not meet the conditions of acceptance, three additional tests shall be run. All the additional tests shall 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.

R337.7.5 Open roof 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 material. The ignition-resistant material shall be labeled for exterior use and shall meet the requirements of Section 704A.2.

3. Fire-retardant-treated wood. The fire-retardant- treated wood shall be labeled for exterior use and shall meet the requirements of 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. One layer of 5 /8-inch (16 mm) Type X gypsum sheathing applied behind an exterior covering on the underside of the roof deck.

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 under- side of the roof deck designed for exterior fire expo- sure, including assemblies using the gypsum panel and sheathing products listed in the Gypsum Associ- ation Fire Resistance Design Manual.

Exception to Section R337.7.5: The following materi- als do not require protection:

Fascia and other architectural trim boards.

3. Exterior exposed underside of roof eave overhangs.

4. Exterior exposed underside of roof eave soffits.

5. Exposed underside of exterior porch ceilings.

6. Exterior exposed underside of floor projections.

7. Exterior underfloor areas.

Exceptions to Section R337.7.2:

1. Exterior wall architectural trim, embellishments, fascias and gutters.

2. Roof or wall top cornice projections and similar assemblies.

3. Deck walking surfaces shall comply with Section R337.9 only. R337.7.3 Exterior wall coverings. The exterior wall cov- ering shall comply with one or more of the following requirements, except as permitted for exterior wall assem- blies complying with Section R337.7.4:

1. Noncombustible material.

2. Ignition-resistant material. The ignition-resistant material shall be labeled for exterior use and shall meet the requirements of Section R337.4.2.

3. Fire-retardant-treated wood. The fire-retardant- treated wood shall be labeled for exterior use and shall meet the requirements of Section 2303.2 of the California Building Code.

R337.7.3.1 Extent of exterior wall covering. Exterior wall coverings shall extend from the top of the founda- tion to the roof, and terminate at 2 inch (50.8 mm) nomi- nal solid wood blocking between rafters at all roof overhangs, or in the case of enclosed eaves, terminate at the enclosure.

R337.7.4 Exterior wall assemblies . Exterior wall assem- blies of buildings or structures shall be constructed using one or more of the following methods, unless they are covered by an exterior wall covering complying with Section R337.7.3:

1. 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.

2. Log wall construction assembly.

3. Assembly that has been tested in accordance with the test procedures for a 10-minute direct flame con- tact exposure test set forth in ASTM E2707 with the conditions of acceptance shown in Section R337.7.4.1.

4. Assembly that meets 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.

5. Assembly suitable for exterior fire exposure with a 1-hour fire-resistance rating, rated from the exterior

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

R337.7.6 Enclosed roof eaves and roof eave soffits. The exposed underside of enclosed roof eaves having either a boxed-in roof eave soffit with a horizontal underside, or sloping rafter tails with an exterior covering applied to the underside of the rafter tails, shall be protected by one or more of the following:

1. Noncombustible material.

2. Ignition-resistant material. The ignition-resistant material shall be labeled for exterior use and shall meet the requirements of Section R337.4.2.

3. Fire-retardant-treated wood. The fire-retardant- treated wood shall be labeled for exterior use and shall meet the requirements of 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. One layer of 5 /8-inch (16 mm) Type X gypsum sheathing applied behind the exterior covering or cladding on the underside of the rafter tails or soffit.

6. The exterior portion of a 1-hour fire resistive exte- rior assembly applied to the underside of the rafter tails or soffit, including assemblies using the gypsum panel and sheathing products listed in the Gypsum Association Fire Resistance Design Manual.

7. Boxed-in roof eave soffit assemblies with a horizon- tal underside that meet the performance criteria in Section R337.7.11 when tested in accordance with the test procedures set forth in ASTM E2957.

8. Boxed-in roof eave soffit assemblies with a horizon- tal underside that meet the performance criteria in accordance with the test procedures set forth in SFM Standard 12-7A-3.

Exception to Section R337.7.6: The following materi- als do not require protection:

Fascia and other architectural trim boards. R337.7.7 Exterior porch ceilings. The exposed underside of exterior porch ceilings shall be protected by one or more of the following:

1. Noncombustible material.

2. Ignition-resistant material. The ignition-resistant material shall be labeled for exterior use and shall meet the requirements of Section R337.4.2.

3. Fire-retardant-treated wood. The fire-retardant- treated wood shall be labeled for exterior use and shall meet the requirements of 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. One layer of 5 /8-inch (16 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, 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. Porch ceiling assemblies with a horizontal under- side that meet the performance criteria in Section R337.7.11 when tested in accordance with the test procedures set forth in ASTM E2957.

8. Porch ceiling assemblies with a horizontal under- side that meet the performance criteria in accor- dance with the test procedures set forth in SFM Standard 12-7A-3.

Exception to Section R337.7.7: Architectural trim boards do not require protection. R337.7.8 Floor projections. The exposed underside of a cantilevered floor projection where a floor assembly extends over an exterior wall shall be protected by one or more of the following:

1. Noncombustible material.

2. Ignition-resistant material. The ignition-resistant material shall be labeled for exterior use and shall meet the requirements of Section R337.4.2.

3. Fire-retardant-treated wood. The fire-retardant- treated wood shall be labeled for exterior use and shall meet the requirements of 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. One layer of 5 /8-inch (16 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 under- side of the floor projection, 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 R337.7.11 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 to Section R337.7.8: Architectural trim boards do not require protection. R337.7.9 Underfloor protection. The underfloor area of elevated or overhanging buildings shall be enclosed to grade in accordance with the requirements of this chapter

3-102 2022 CALIFORNIA RESIDENTIAL CODE

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

5. One layer of 5 /8-inch (16 mm) Type X gypsum sheathing applied behind an exterior covering on the underside of the appendage 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 under- side of the appendage, including assemblies using the gypsum panel and sheathing products listed in the Gypsum Association Fire Resistance Design Manual.

7. The underside of an appendage assembly that meets the performance criteria in Section R337.7.11 when tested in accordance with the test procedures set forth in ASTM E2957.

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

Exception to Section R337.7.10: Structural columns and beams do not require protection when they are 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-grove, or set close together and well spiked. R337.7.11 Conditions of acceptance when tested in accordance with ASTM E2957. The test shall be con- ducted on a minimum of three test specimens and the conditions of acceptance in 1 through 3 below shall be met. If any one of the three tests does not meet the condi- tions of acceptance, three additional tests shall be run. All of the additional tests shall meet the conditions of acceptance.

1. Absence of flame penetration of the eaves or hori- zontal projection assembly at any time.

2. Absence of structural failure of the eaves or hori- zontal projection subassembly at any time.

3. Absence of sustained combustion of any kind at the conclusion of the 40-minute test.

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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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