CBC · California Building Code
Lumber and wood structural panel grading and labeling requirements
For builders and inspectors: the CBC requires load‑bearing sawn lumber to carry a grade mark from an agency accredited under DOC PS 20 (or an accepted inspection certificate in limited cases), and requires wood structural panels to conform to DOC PS 1/PS 2 or ANSI/APA PRP 210 with a grade mark showing grade, bond classification and Performance Category — the Performance Category printed on the panel is the value the code uses as the panel’s “nominal thickness” for span and fastening rules (see § 2303.1.1 and § 2303.1.5).
Last reviewed: July 5, 2026
What the code requires — 2-4 sentences
Sawn lumber used for load‑supporting purposes must carry a grade mark from a lumber grading or inspection agency accredited under DOC PS 20 (or an equivalent accreditation) or be accompanied by an accepted certificate of inspection — see § 2303.1.1. Wood structural panels used structurally must conform to DOC PS 1, DOC PS 2 or ANSI/APA PRP 210 and each panel must be identified by trademark or grade mark showing grade, bond classification and Performance Category; the Performance Category is to be treated as the panel’s “nominal panel thickness” whenever the CBC references panel thickness — see § 2303.1.5.
Requirements in detail
1) Sawn lumber — what marking/identification is required
- Sawn lumber used for load‑bearing or other load‑supporting purposes must be identified by the grade mark of a lumber grading or inspection agency approved by an accreditation body that complies with DOC PS 20 (or equivalent). Grading practices and identification must follow the approved agency’s published rules — § 2303.1.1.
- In lieu of a grade mark on the piece, a certificate of inspection (showing species and grade) issued by an approved lumber grading/inspection agency is permitted for precut, remanufactured, rough‑sawn lumber and for sizes larger than 3 in. nominal thickness — § 2303.1.1.1.
- End‑jointing: approved end‑jointed lumber may be used interchangeably with solid‑sawn members of the same species and grade. If the end‑jointed lumber is used in an assembly that must have a fire‑resistance rating, the grade mark must include the designation “Heat Resistant Adhesive” or “HRA” — § 2303.1.1.2.
2) Wood structural panels — required markings and standards
- Wood structural panels used structurally (siding, roof/wall sheathing, subflooring, diaphragms, built‑up members) must conform to the panel standards DOC PS 1, DOC PS 2 or ANSI/APA PRP 210 — § 2303.1.5.
- Each panel or member must be identified for: (1) grade, (2) bond classification and (3) Performance Category by the trademark/grade mark of an approved testing and grading agency — § 2303.1.5.
- The panel’s Performance Category value is the value to be used as the panel’s “nominal panel thickness” wherever the CBC references panel thickness — § 2303.1.5.
- Components and fabricated panel products used structurally must be designed/produced per the applicable standards listed in Section 2306.1 and also identified by an agency trademark indicating conformity to that standard — § 2303.1.5.
- Permanently exposed exterior panels must be of “exterior type.” An exception: wood structural roof sheathing that is exposed to the outdoors only on the underside (i.e., roof sheathing visible from below) may be Exposure 1 type rather than exterior type — § 2303.1.5.
3) How the marking information is used in compliance decisions
- Inspectors and designers must confirm the stamp/trademark shows the required items (grade, bond, performance category) from an accredited/approved agency; absence of those items is nonconforming under § 2303.1.1 and § 2303.1.5.
- When code language refers to “panel thickness” for span tables, fastener schedules or other limits, use the Performance Category printed on the panel stamp (not simply a measured physical thickness) — § 2303.1.5.
Quick reference table (decision‑relevant items)
| Material / situation | Required marking or documentation | Acceptable standard(s) / notes | Code Reference |
|---|---|---|---|
| Sawn lumber (load‑supporting) | Grade mark from agency accredited under DOC PS 20, showing species/grade | Or certificate of inspection for precut/remanufactured/rough‑sawn or >3" nominal | § 2303.1.1; § 2303.1.1.1 |
| End‑jointed lumber | Same grade mark; if used in fire‑resistance rated assembly, grade mark must include “Heat Resistant Adhesive” or “HRA” | End‑jointed allowed interchangeable with same species/grade | § 2303.1.1.2 |
| Wood structural panels (sheathing, subfloor, siding) | Trademark/grade mark showing grade, bond classification and Performance Category | Panels must conform to DOC PS 1, DOC PS 2 or ANSI/APA PRP 210 | § 2303.1.5 |
| Panel thickness used in code tables | Use the Performance Category listed on the stamp as the “nominal panel thickness” | Performance Category governs span/fastener selections in other sections | § 2303.1.5 |
| Panels permanently exposed outdoors | Must be exterior‑type panels | Exception: roof sheathing exposed to outdoors on underside may be Exposure 1 type | § 2303.1.5 |
| Fabricated panel components | Must be designed/fabricated per standards in § 2306.1 and bear trademark showing conformity | See Section 2306.1 for applicable component standards | § 2303.1.5; § 2306.1 |
Exceptions & special cases
- Certificate of inspection permitted instead of a mark for certain lumber (precut, remanufactured, rough‑sawn, and thickness > 3 in.) — § 2303.1.1.1.
- End‑jointed lumber may substitute for solid‑sawn members of equal species and grade; when used where a fire‑resistance rating is required, the grade mark must include “Heat Resistant Adhesive” or “HRA” — § 2303.1.1.2.
- Wood structural roof sheathing that is permanently exposed to the outdoors only on the underside may be Exposure 1 rather than exterior type; otherwise permanent outdoor exposure requires exterior type panels — § 2303.1.5.
If you need to know what information must literally appear on a particular grade stamp (abbreviations, agency trademarks, bond class codes, how Performance Category is shown), the CBC requires the grade/bond/category but the exact stamp format is determined by the approved grading/testing agency’s marking rules (DOC PS 1/2, DOC PS 20, ANSI/APA PRP 210). The CBC text in the files does not reproduce every stamping format; check the agency’s rules and the product stamp itself for the full data.
Common mistakes
- Accepting a panel or lumber item with no grade mark or with a mark from a non‑accredited/unknown agency. The CBC requires agency accreditation per DOC PS 20 (lumber) or the applicable panel standards — § 2303.1.1 and § 2303.1.5.
- Treating the physical measured thickness of a panel as the code “panel thickness” instead of using the Performance Category value shown on the stamp — § 2303.1.5.
- Overlooking the HRA requirement for end‑jointed lumber used in fire‑resistance‑rated assemblies — § 2303.1.1.2.
- Using Exposure 1 panels where panels are permanently exposed to weather (except the permitted underside roof sheathing case) — § 2303.1.5.
Worked example — selecting exterior wall sheathing (concrete scenario)
Scenario: You are specifying wall sheathing for a two‑story house. Plans call for plywood sheathing with a 24 in. on‑center stud spacing and the structural schedule references “panel thickness” for fastener spacing and lateral shear values.
Steps to verify code compliance:
- Specify a panel that conforms to DOC PS 1 or DOC PS 2 (or ANSI/APA PRP 210 for applicable products). Confirm the manufacturer’s product will be graded/marked by an approved agency — § 2303.1.5.
- On delivery, confirm the stamp/trademark includes: (a) grade, (b) bond classification, (c) Performance Category. Use the Performance Category printed on the stamp as the nominal thickness when consulting CBC span/fastener/shear tables — § 2303.1.5.
- If the wall sheathing will be permanently exposed to exterior weather (e.g., exposed siding panels), specify an exterior‑type panel. If the panel is only roof sheathing visible from below, Exposure 1 may be acceptable (but not for exterior siding) — § 2303.1.5.
- Example numeric check (typical): If the stamp shows Performance Category “7/16” (Performance Category value = 7/16), use that 7/16 value for any CBC table entries that call for panel thickness when determining allowable spans and fastener spacing. If another code location (e.g., residential provisions) requires a minimum 7/16 performance category for a specific application (such as brick tie attachment), confirm the panel’s Performance Category meets that minimum — see § 2303.1.5 and residential examples.
Note: the CBC text requires you to use the Performance Category from the stamp; specific span/fastener values come from the relevant tables and standards referenced elsewhere in the code (e.g., Chapter 23 tables and APA/SDPWS values).
Related provisions
- § 2303.1.1 — Sawn lumber identification and grading requirements (DOC PS 20 accreditation).
- § 2303.1.1.1 — Certificate of inspection alternative for certain lumber.
- § 2303.1.1.2 — End‑jointed lumber and “HRA” marking requirement for fire‑resistance‑rated assemblies.
- § 2303.1.5 — Wood structural panel conformity, marking, Performance Category and exterior exposure rules.
- Section 2306.1 — Standards for panel components and fabrication (panels/components must be identified as conforming per § 2303.1.5).
- Residential code references on panel identification and some minimum performance categories (examples and applications): R803.2 / R404.2 (see for application‑specific minimums).
Code references
Grounded in the retrieved California Building Code — click a citation to read the verbatim passage:
CBC § 2303.1.1 High relevance — show source text
2303.1.1 Sawn lumber. Sawn lumber used for load-supporting purposes, including end-jointed or edge-glued lumber, machine stress-rated or machine-evaluated lumber, shall be identified by the grade mark of a lumber grading or inspection agency that has been approved by an accreditation body that complies with DOC PS 20 or equivalent. Grading practices and identification shall comply with rules published by an agency approved in accordance with the procedures of DOC PS 20 or equivalent procedures.
2303.1.1.1 Certificate of inspection. In lieu of a grade mark on the material, a certificate of inspection as to species and grade issued by a lumber grading or inspection agency meeting the requirements of this section is permitted to be accepted for precut, remanufactured or rough-sawn lumber and for sizes larger than 3 inches (76 mm) nominal thickness.
2303.1.1.2 End-jointed lumber. Approved end-jointed lumber is permitted to be used interchangeably with solid-sawn members of the same species and grade. End-jointed lumber used in an assembly required to have a fire-resistance rating shall have the designation “Heat Resistant Adhesive” or “HRA” included in its grade mark.
2303.1.2 Prefabricated wood I-joists. Structural capacities and design provisions for prefabricated wood I-joists shall be established and monitored in accordance with ASTM D5055.
2303.1.3 Structural glued-laminated timber. Glued-laminated timbers shall be manufactured and identified as required in ANSI/APA 190.1 and ASTM D3737.
2303.1.3.1 Additional requirements. [DSA-SS, DSA-SS/CC and OSHPD 1, 1R, 2, 4 & 5] The construction documents shall indicate the following: 1. Dry or wet service conditions. 2. Laminating combinations and stress requirements. 3. Species group. 4. Preservative material and retention, when preservative treatment is required. 5. Provisions for protection during shipping and field handling, such as sealing and wrapping in accordance with AITC 111.
When mechanical reinforcement such as radial tension reinforcement is required, such reinforcement shall comply with AITC 404 and shall be detailed accordingly in the construction documents. Construction documents shall specify that the moisture content of laminations at the time of manufacture shall not exceed 12 percent for dry conditions of use.
The design of fasteners and connections shall comply with AITC 117, Section I, Item 6 (Connection Design), and NDS Appendix E.
2303.1.4 Cross-laminated timber. Cross-laminated timbers shall be manufactured and identified in accordance with ANSI/APA PRG 320.
2303.1.4.1 Additional requirements. [DSA-SS & DSA-SS/CC & OSHPD 1, 1R, 2, 4 & 5] Requirements in Section 2303.1.3.1 shall apply to cross-laminated timber.
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**2303.1.5 Wood structural panels.
CBC § 2303.1.5 High relevance — show source text
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2303.1.5 Wood structural panels. Wood structural panels, where used structurally (including those used for siding, roof and wall sheathing, subflooring, diaphragms and built-up members), shall conform to the requirements for their type in DOC PS 1, DOC PS 2 or ANSI/APA PRP 210. Each panel or member shall be identified for grade, bond classification, and Performance Category by the trademarks of an approved testing and grading agency. The Performance Category value shall be used as the “nominal panel thickness” or “panel thickness” whenever referenced in this code. Wood structural panel components shall be designed and fabricated in accordance with the applicable standards listed in Section 2306.1 and identified by the trademarks of an approved testing and inspection agency indicating conformance to the applicable standard. In addition, wood structural panels where permanently exposed in outdoor applications shall be of exterior type, except that wood structural panel roof sheathing exposed to the outdoors on the underside is permitted to be Exposure 1 type.
2303.1.6 Fiberboard. Fiberboard for its various uses shall conform to ASTM C208. Fiberboard sheathing, where used structurally, shall be identified by an approved agency as conforming to ASTM C208.
2303.1.6.1 Jointing. To ensure tight-fitting assemblies, edges shall be manufactured with square, shiplapped, beveled, tongue-and-groove or U-shaped joints.
2303.1.6.2 Roof insulation. Where used as roof insulation in all types of construction, fiberboard shall be protected with an approved roof covering.
2303.1.6.3 Wall insulation. Where installed and fireblocked to comply with Chapter 7, fiberboards are permitted as wall insulation in all types of construction. In fire walls and fire barriers, unless treated to comply with Section 803.1 for Class A materials, the boards shall be cemented directly to the concrete, masonry or other noncombustible base and shall be protected with an approved noncombustible veneer anchored to the base without intervening airspaces.
2303.1.6.3.1 Protection. Fiberboard wall insulation applied on the exterior of foundation walls shall be protected below ground level with a bituminous coating.
2303.1.7 Hardboard. Hardboard siding shall conform to the requirements of ANSI A135.6 and, where used structurally, shall be identified by the label of an approved agency. Hardboard underlayment shall meet the strength requirements of [7] / 32 -inch (5.6 mm) or [1] / 4 -inch (6.4 mm) service class hardboard planed or sanded on one side to a uniform thickness of not less than 0.200 inch (5.1 mm). Prefinished hardboard paneling shall meet the requirements of ANSI A135.5. Other basic hardboard products shall meet the requirements of ANSI A135.4. Hardboard products shall be installed in accordance with manufacture’s recommendations.
2303.1.8 Particleboard. Particleboard shall conform to ANSI A208.1. Particleboard shall be identified by the grade mark or certificate of inspection issued by an approved agency. Particleboard shall not be utilized for applications other than indicated in this section unless the particleboard complies with the provisions of Section 2306.3.
CBC § 25.4 High relevance — show source text
plywood
sidinge
except
Group 5
Species,
ANSI/APA
PRP 210
sidinge|19/32|19/32|13/4 16
Gage|185|280|375|475|—|—|—|—|—| |For SI: 1 inch = 25.4 mm, 1 pound per foot = 14.5939 N/m.
a. For framing of other species: (1) Find specific gravity for species of lumber in ANSI/AWC NDS. (2) For staples find shear value from table for Structural I panels (regardless of
actual grade) and multiply value by 0.82 for species with specific gravity of 0.42 or greater, or 0.65 for all other species.
b. Panel edges backed with 2-inch nominal or wider framing. Install panels either horizontally or vertically. Space fasteners maximum 6 inches on center along intermediate
framing members for3/8-inch and7/16-inch panels installed on studs spaced 24 inches on center. For other conditions and panel thickness, space fasteners maximum 12 inches
on center on intermediate supports.
c. 3/8-inch panel thickness or siding with a span rating of 16 inches on center is the minimum recommended where applied directly to framing as exterior siding. For grooved
panel siding, the nominal panel thickness is the thickness of the panel measured at the point of fastening.
d. Framing at adjoining panel edges shall be 3 inches nominal or wider.
e. Values apply to all-veneer plywood. Thickness at point of fastening on panel edges governs shear values.
f. Where panels are applied on both faces of a wall and fastener spacing is less than 6 inches on center on either side, panel joints shall be offset to fall on different framing
members, or framing shall be 3 inches nominal or thicker at adjoining panel edges.
g. In Seismic Design Category D, E or F, where shear design values exceed 350 pounds per linear foot, all framing members receiving edge fastening from abutting panels shall be
not less than a single 3-inch nominal member, or two 2-inch nominal members fastened together in accordance with Section 2306.1 to transfer the design shear value
between framing members. Wood structural panel joint and sill plate nailing shall be staggered at all panel edges. See AWC SDPWS for sill plate size and anchorage
requirements.
h. Staples shall have a minimum crown width of7/16 inch and shall be installed with their crowns parallel to the long dimension of the framing members.
i. For shear loads of normal or permanent load duration as defined by the ANSI/AWC NDS, the values in the table shall be multiplied by 0.63 or 0.56, respectively.|For SI: 1 inch = 25.4 mm, 1 pound per foot = 14.5939 N/m.
a. For framing of other species: (1) Find specific gravity for species of lumber in ANSI/AWC NDS. (2) For staples find shear value from table for Structural I panels (regardless of
actual grade) and multiply value by 0.82 for species with specific gravity of 0.42 or greater, or 0.65 for all other species.
b. Panel edges backed with 2-inch nominal or wider framing. Install panels either horizontally or vertically.CBC § 2303.1.3.1 High relevance — show source text
2303.1.3.1 Additional requirements. [DSA-SS, DSA-SS/CC and OSHPD 1, 1R, 2, 4 & 5] The construction documents shall indicate the following: 1. Dry or wet service conditions. 2. Laminating combinations and stress requirements. 3. Species group. 4. Preservative material and retention, when preservative treatment is required. 5. Provisions for protection during shipping and field handling, such as sealing and wrapping in accordance with AITC 111.
When mechanical reinforcement such as radial tension reinforcement is required, such reinforcement shall comply with AITC 404 and shall be detailed accordingly in the construction documents. Construction documents shall specify that the moisture content of laminations at the time of manufacture shall not exceed 12 percent for dry conditions of use.
The design of fasteners and connections shall comply with AITC 117, Section I, Item 6 (Connection Design), and NDS Appendix E.
2303.1.4 Cross-laminated timber. Cross-laminated timbers shall be manufactured and identified in accordance with ANSI/APA PRG 320.
2303.1.4.1 Additional requirements. [DSA-SS & DSA-SS/CC & OSHPD 1, 1R, 2, 4 & 5] Requirements in Section 2303.1.3.1 shall apply to cross-laminated timber.
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2303.1.5 Wood structural panels. Wood structural panels, where used structurally (including those used for siding, roof and wall sheathing, subflooring, diaphragms and built-up members), shall conform to the requirements for their type in DOC PS 1, DOC PS 2 or ANSI/APA PRP 210. Each panel or member shall be identified for grade, bond classification, and Performance Category by the trademarks of an approved testing and grading agency. The Performance Category value shall be used as the “nominal panel thickness” or “panel thickness” whenever referenced in this code. Wood structural panel components shall be designed and fabricated in accordance with the applicable standards listed in Section 2306.1 and identified by the trademarks of an approved testing and inspection agency indicating conformance to the applicable standard. In addition, wood structural panels where permanently exposed in outdoor applications shall be of exterior type, except that wood structural panel roof sheathing exposed to the outdoors on the underside is permitted to be Exposure 1 type.
2303.1.6 Fiberboard. Fiberboard for its various uses shall conform to ASTM C208. Fiberboard sheathing, where used structurally, shall be identified by an approved agency as conforming to ASTM C208.
2303.1.6.1 Jointing. To ensure tight-fitting assemblies, edges shall be manufactured with square, shiplapped, beveled, tongue-and-groove or U-shaped joints.
2303.1.6.2 Roof insulation. Where used as roof insulation in all types of construction, fiberboard shall be protected with an approved roof covering.
CBC § 0.63 High relevance — show source text
Staples shall have a minimum crown width of7/16 inch and shall be installed with their crowns parallel to the long dimension of the framing members.
i. For shear loads of normal or permanent load duration as defined by the ANSI/AWC NDS, the values in the table shall be multiplied by 0.63 or 0.56, respectively.|For SI: 1 inch = 25.4 mm, 1 pound per foot = 14.5939 N/m.
a. For framing of other species: (1) Find specific gravity for species of lumber in ANSI/AWC NDS. (2) For staples find shear value from table for Structural I panels (regardless of
actual grade) and multiply value by 0.82 for species with specific gravity of 0.42 or greater, or 0.65 for all other species.
b. Panel edges backed with 2-inch nominal or wider framing. Install panels either horizontally or vertically. Space fasteners maximum 6 inches on center along intermediate
framing members for3/8-inch and7/16-inch panels installed on studs spaced 24 inches on center. For other conditions and panel thickness, space fasteners maximum 12 inches
on center on intermediate supports.
c. 3/8-inch panel thickness or siding with a span rating of 16 inches on center is the minimum recommended where applied directly to framing as exterior siding. For grooved
panel siding, the nominal panel thickness is the thickness of the panel measured at the point of fastening.
d. Framing at adjoining panel edges shall be 3 inches nominal or wider.
e. Values apply to all-veneer plywood. Thickness at point of fastening on panel edges governs shear values.
f. Where panels are applied on both faces of a wall and fastener spacing is less than 6 inches on center on either side, panel joints shall be offset to fall on different framing
members, or framing shall be 3 inches nominal or thicker at adjoining panel edges.
g. In Seismic Design Category D, E or F, where shear design values exceed 350 pounds per linear foot, all framing members receiving edge fastening from abutting panels shall be
not less than a single 3-inch nominal member, or two 2-inch nominal members fastened together in accordance with Section 2306.1 to transfer the design shear value
between framing members. Wood structural panel joint and sill plate nailing shall be staggered at all panel edges. See AWC SDPWS for sill plate size and anchorage
requirements.
h. Staples shall have a minimum crown width of7/16 inch and shall be installed with their crowns parallel to the long dimension of the framing members.
i. For shear loads of normal or permanent load duration as defined by the ANSI/AWC NDS, the values in the table shall be multiplied by 0.63 or 0.56, respectively.|For SI: 1 inch = 25.4 mm, 1 pound per foot = 14.5939 N/m.
a. For framing of other species: (1) Find specific gravity for species of lumber in ANSI/AWC NDS. (2) For staples find shear value from table for Structural I panels (regardless of
actual grade) and multiply value by 0.82 for species with specific gravity of 0.42 or greater, or 0.65 for all other species.
b. Panel edges backed with 2-inch nominal or wider framing. Install panels either horizontally or vertically.CBC § 2.1 High relevance — show source text
R404.2.1 Identification. Load-bearing lumber shall be identified by the grade mark of a lumber grading or inspection agency that has been approved by an accreditation body that complies with DOC PS 20. In lieu of a grade mark, a certificate of inspection issued by a lumber grading or inspection agency meeting the requirements of this section shall be accepted. Wood structural panels shall conform to DOC PS 1 or DOC PS 2 and shall be identified by a grade mark or certificate of inspection issued by an approved agency.
R404.2.2 Stud size. The studs used in foundation walls shall be 2-inch by 6-inch (51 mm by 152 mm) members. Where spaced 16 inches (406 mm) on center, a wood species with an F b value of not less than 1,250 pounds per square inch (8619 kPa) as listed in ANSI AWC NDS shall be used. Where spaced 12 inches (305 mm) on center, an F b of not less than 875 psi (6033 kPa) shall be required.
R404.2.3 Height of backfill. For wood foundations that are not designed and installed in accordance with AWC PWF, the height of backfill against a foundation wall shall not exceed 4 feet (1219 mm). Where the height of fill is more than 12 inches (305 mm) above the interior grade of a crawl space or floor of a basement, the thickness of the plywood sheathing shall meet the requirements of Table R404.2.3.
TABLE R404.2.3—PLYWOOD GRADE AND THICKNESS FOR WOOD
FOUNDATION CONSTRUCTION (30 pcf equivalent-fluid weight soil pressure)Col2 Col3 Col4 Col5 Col6 Col7 Col8 ** HEIGHT OF FILL**
(inches)** STUD SPACING**
(inches)** FACE GRAIN ACROSS STUDS** ** FACE GRAIN ACROSS STUDS** ** FACE GRAIN ACROSS STUDS** ** FACE GRAIN PARALLEL TO STUDS** ** FACE GRAIN PARALLEL TO STUDS** ** FACE GRAIN PARALLEL TO STUDS** ** HEIGHT OF FILL**
(inches)** STUD SPACING**
(inches)** Gradea** ** Minimum thickness**
(inches)** Span**
rating** Gradea** ** Minimum thickness**
(inches)b, c** Span**
rating24 12 B 15/32 32/16 A 15/32 32/16 24 12 B 15/32 32/16 B 15/32 c 32/16 24 16 B 15/32 32/16 A 15/32 c 32/16 24 16 B 15/32 32/16 B 19/32 c (4, 5 ply) 40/20 36 12 B 15/32 32/16 A 15/32 32/16 36 12 B 15/32 32/16 B 15/32 c (4, 5 ply) 32/16 36 12 B 15/32 32/16 B 19/32 (4, CBC § 0.35 High relevance — show source text
Where the specific gravity of the wood species used for wall framing is greater than or equal to 0.35 but less than 0.42 in accordance with AWC NDS, nail spacing in the field of
the panel shall be multiplied by 0.67. Where the specific gravity of the wood species used for wall framing is less than 0.35, fastening of the wall sheathing shall be designed in
accordance with AWC NDS.|For SI: 1 inch = 25.4 mm, 1 mile per hour = 0.447 m/s.
a. Panel strength axis shall be parallel or perpendicular to supports. Three-ply plywood sheathing with studs spaced more than 16 inches on center shall be applied with panel
strength axis perpendicular to supports.
b. The table is based on wind pressures acting toward and away from building surfaces in accordance with Section 30.4 of ASCE 7. Lateral requirements shall be in accordance
with Section 2305 or 2308.
c. Wood structural panels with span ratings of wall-16 or wall-24 shall be permitted as an alternative to panels with a 24/0 span rating. Plywood siding rated 16 on center or 24 on
center shall be permitted as an alternative to panels with a 24/16 span rating. Wall-16 and plywood siding 16 on center shall be used with studs spaced not more than 16
inches on center.
d. Where the specific gravity of the wood species used for wall framing is greater than or equal to 0.35 but less than 0.42 in accordance with AWC NDS, nail spacing in the field of
the panel shall be multiplied by 0.67. Where the specific gravity of the wood species used for wall framing is less than 0.35, fastening of the wall sheathing shall be designed in
accordance with AWC NDS.|2304.7 Interior paneling. Softwood wood structural panels used for interior paneling shall conform to the provisions of Chapter 8 and shall be installed in accordance with Table 2304.10.2. Panels shall comply with DOC PS 1, DOC PS 2 or ANSI/APA PRP 210. Prefinished hardboard paneling shall meet the requirements of ANSI A135.5. Hardwood plywood shall conform to HPVA HP-1.
2304.8 Floor and roof sheathing. Structural floor sheathing and structural roof sheathing shall comply with Sections 2304.8.1 and 2304.8.2, respectively.
CBC § 50.8 High relevance — show source text
- Wood floor assemblies using dimension lumber or structural composite lumber equal to or greater than 2-inch by 10-inch (50.8 mm by 254 mm) nominal dimension, or other approved floor assemblies demonstrating equivalent fire performance.
- Wood floor assemblies less than 600 square feet (55.7 m [2] ) within detached accessory structures with no habitable space above them.
R302.14 Combustible insulation clearance. Combustible insulation shall be separated not less than 3 inches (76 mm) from recessed luminaires, fan motors and other heat-producing devices.
Exception: Where heat-producing devices are listed for lesser clearances, combustible insulation complying with the listing requirements shall be separated in accordance with the conditions stipulated in the listing.
Recessed luminaires installed in the building thermal envelope shall meet the requirements of the California Energy Code .
R302.15 Fire-retardant-treated wood. Fire-retardant-treated wood (FRTW) is any wood product that, when impregnated with chemicals by a pressure process or other means during manufacture, shall have, when tested in accordance with ASTM E84 or UL 723, a listed flame spread index of 25 or less. In addition, the ASTM E84 or UL 723 test shall be continued for an additional 20-minute period and the flame front shall not progress more than 10.5 feet (3200 mm) beyond the center line of the burners at any time during the test.
R302.15.1 Pressure process. For wood products impregnated with chemicals by a pressure process, the process shall be performed in closed vessels under pressures not less than 50 pounds per square inch gauge (psig) (344.7 kPa).
R302.15.2 Other means during manufacture. For wood products impregnated with chemicals by other means during manufacture, the treatment shall be an integral part of the manufacturing process of the wood product. The treatment shall provide permanent protection to all surfaces of the wood product. The use of paints, coating, stains or other surface treatments is not an approved method of protection as required by this section.
R302.15.3 Testing. For fire-retardant-treated wood products, the front and back faces of the wood product shall be tested in accordance with and produce the results required in Section R302.15.
R302.15.3.1 Fire testing of fire-retardant-treated wood structural panels. Fire-retardant-treated wood structural panels shall be tested with a ripped or cut longitudinal gap of [1] / 8 inch (3.2 mm).
302.15.4 Labeling. In addition to the labels required by Section R802.1.1 for sawn lumber and Section R803.2.1 for wood structural panels, each piece of fire-retardant-treated lumber and fire-retardant-treated wood structural panel shall be labeled. The label shall contain:
The identification mark of an approved agency in accordance with Section 1703.5 of the California Building Code.
Identification of the treating manufacturer.
The name of the fire-retardant treatment.
The species of wood treated.
Flame spread index and smoke-developed index.
Method of drying after treatment.
Conformance to applicable standards in accordance with Sections R302.15.5 through R302.15.10.
For FRTW exposed to weather, or a damp or wet location, the words “No increase in the listed classification when subjected to the Standard Rain Test” (ASTM D2898).
CBC § 2308.10 High relevance — show source text
walls 2308.10 Calculated fire resistance 722.6 Ceiling framing 2308.11 Connectors and fasteners 2304.10,
2308.5
Contacting concrete, masonry or earth 2304.12.1.3, 2304.12.1.4, 2304.12.2.1, 2304.12.2.2, 2304.12.2.6 Cross-laminated timber 2301.2, 2303.1, 2303.1.4, 2304.11.2.1, 2304.11.3.1, 2304.11.4.1 Cutting, notching and boring of dimensional wood framing 2308.6 Decay, protection against 2304.12 Diaphragms 2305.1, 2305.2, 2306.2 Dimensions 2301.2 Draftstopping 718.3, 718.4 End-jointed lumber 2303.1.1.2 Fiberboard 2303.1.6, Table 2306.3(2) Fireblocking 718.2 Fire-retardant treated 2303.2 Floor and roof framing (see Floor Construction, Wood) 2304.4 Floor sheathing 2304.8 Foundation 1807.1.4, 2304.10.6.2, 2304.12.1.2, 2308.10.8.1, 2308.7 Grade, lumber 2303.1.1
INDEX-22 2025 CALIFORNIA BUILDING CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
INDEX
Hardboard 2303.1.7 Heavy timber construction 602.4, 2304.11
Hurricane shutters 1609.2
I-joist 2303.1.2 Inspection, special 1705.12.1, 1705.13.2, 1705.5 Lateral force-resisting systems 2305 Light-frame construction, conventional 2308 Load and resistance factor design 2307
Moisture content 2303.1.9.2, 2303.2.9, 2303.7, 2304.9.5.1, Table 2305.2(1), Table 2305.2(2) Nails and staples 2303.6 Plywood, hardwood 2303.3 Preservative treated 1402.6, 1402.9,
2303.1.9 Roof framing (see Roof Construction, Wood)
2304.4 Roof sheathing 2304.8 Seismic provisions 2305, 2306, 2308.10.10, 2308.10.6, 2308.10.8 Shear walls 2305, 2306.3 Standards and quality, minimum 2303 Structural panels 2303.1.5 Supporting concrete or masonry 2304.13 Termite, protection against 2304.12 Trusses 2303.4
Veneer Chapter 14 Wall framing (see Wall, Wood Construction)
2304.3 Wall sheathing, exterior 2304.6 Wood Frame Construction Manual
CBC § 0.080 Medium relevance — show source text
1/4″|4d casing (11/2″ × 0.080″); or
4d finish (11/2″ × 0.072″)|6|12| |41.3/8″|6d casing (2″ × 0.099″); or
6d finish (2″ × 0.092″)
(Panel supports at 24 inches)|6|12| |For SI: 1 inch = 25.4 mm.
a. Nails spaced at 6 inches at intermediate supports where spans are 48 inches or more. For nailing of wood structural panel and particleboard diaphragms and shear walls, refer
to Section 2305. Nails for wall sheathing are permitted to be common, box or casing.
b. Spacing shall be 6 inches on center on the edges and 12 inches on center at intermediate supports for nonstructural applications. Panel supports at 16 inches (20 inches if
strength axis in the long direction of the panel, unless otherwise marked).
c. Where a rafter is fastened to an adjacent parallel ceiling joist in accordance with this schedule and the ceiling joist is fastened to the top plate in accordance with this schedule,
the number of toenails in the rafter shall be permitted to be reduced by one nail.
d. RSRS is a Roof Sheathing Ring Shank nail meeting the specifications in ASTM F1667.
e. Tabulated fastener requirements apply where the basic wind speed,V, is less than 140 mph. For wood structural panel roof sheathing attached to gable-end roof framing and
to intermediate supports within 48 inches of roof edges and ridges, nails shall be spaced at 4 inches on center where the basic wind speed,V, is greater than 130 mph in Expo-
sure B or greater than 110 mph in Exposure C. Spacing exceeding 6 inches on center at intermediate supports shall be permitted where the fastening is designed per the AWC
NDS. Where the specific gravity of the wood species used for roof framing is greater than or equal to 0.35 but less than 0.42 in accordance with AWC NDS, fastening of roof
sheathing shall be with RSRS-03 (21/2″ × 0.131″ × 0.281″ head) nails unless alternative fastening is designed in accordance with AWC NDS. Where the specific gravity of the wood
species used for roof framing is less than 0.35, fastening of the roof sheathing shall be designed in accordance with AWC NDS.
f. Fastening is only permitted where the basic wind speed,V, is less than or equal to 110 mph and where fastening is to wood framing of a species with specific gravity greater
than or equal to 0.42 in accordance with AWC NDS.
g. Nails and staples are carbon steel meeting the specifications of ASTM F1667. Connections using nails and staples of other materials, such as stainless steel, shall be designed
by acceptable engineering practice or approved under Section 104.2.3.|For SI: 1 inch = 25.4 mm.
a. Nails spaced at 6 inches at intermediate supports where spans are 48 inches or more. For nailing of wood structural panel and particleboard diaphragms and shear walls, refer
to Section 2305. Nails for wall sheathing are permitted to be common, box or casing.
b. Spacing shall be 6 inches on center on the edges and 12 inches on center at intermediate supports for nonstructural applications.CBC § 1.1 Medium relevance — show source text
SECTION R602—WOOD WALL FRAMING
R602.1 General. Wood and wood-based products used for load-supporting purposes shall conform to the applicable provisions of this section.
R602.1.1 Sawn lumber. Sawn lumber shall be identified by a grade mark of an accredited lumber grading or inspection agency and have design values certified by an accreditation body that complies with DOC PS 20. In lieu of a grade mark, a certification of inspection issued by a lumber grading or inspection agency meeting the requirements of this section shall be accepted.
Note: See Section R301.1.1.1 for limited-density owner- built rural dwellings.
R602.1.2 End-jointed lumber. Approved end-jointed lumber identified by a grade mark conforming to Section R602.1 shall be permitted to be used interchangeably with solid-sawn members of the same species and grade. End-jointed lumber used in an assembly required elsewhere in this code to have a fire-resistance rating shall have the designation “Heat Resistant Adhesive” or “HRA” included in its grade mark.
R602.1.3 Structural glued-laminated timbers. Glued-laminated timbers shall be manufactured and identified as required in ANSI A190.1, ANSI 117 and ASTM D3737.
R602.1.4 Structural log members. Structural log members shall comply with the provisions of ICC 400.
R602.1.5 Structural composite lumber. Structural capacities for structural composite lumber shall be established and monitored in accordance with ASTM D5456.
R602.1.6 Cross-laminated timber. Cross-laminated timber shall be manufactured and identified as required by ANSI/APA PRG 320.
R602.1.7 Engineered wood rim board. Engineered wood rim boards shall conform to ANSI/APA PRR 410 or shall be evaluated in accordance with ASTM D7672. Structural capacities shall be in accordance with either ANSI/APA PRR 410 or established in accordance with ASTM D7672. Rim boards conforming to ANSI/APA PRR 410 shall be marked in accordance with that standard.
R602.1.8 Wood structural panels. Wood structural panel sheathing shall conform to DOC PS 1, DOC PS 2 or, when manufactured in Canada, CSA O325 or CSA O437. Panels shall be identified for grade, bond classification, and performance category by a grade mark or certificate of inspection issued by an approved agency.
R602.1.9 Particleboard. Particleboard shall conform to ANSI A208.1. Particleboard shall be identified by the grade mark or certificate of inspection issued by an approved agency.
R602.1.10 Fiberboard. Fiberboard shall conform to ASTM C208. Fiberboard sheathing, where used structurally, shall be identified by an approved agency as conforming to ASTM C208.
R602.1.11 Structural insulated panels. Structural insulated panels shall be manufactured and identified in accordance with ANSI/APA PRS 610.1.
R602.2 Grade. Studs shall be a minimum No. 3, standard or stud grade lumber.
Exception: Bearing studs not supporting floors and nonbearing studs shall be permitted to be utility grade lumber, provided that the studs are spaced in accordance with Table R602.3(5).
Frequently asked questions
What if a delivered lumber bundle lacks a visible grade stamp?
If the grade stamp is absent but the supplier provides a certificate of inspection from an approved grading agency that documents species and grade (and the product qualifies under § 2303.1.1.1 criteria), that certificate may be accepted — see § 2303.1.1.1.
Can I rely on the measured thickness of a panel for design?
No — where the CBC references “panel thickness,” you must use the Performance Category value printed on the panel’s grade mark as the panel’s nominal thickness per § 2303.1.5.
Is end‑jointed lumber allowed in structural framing?
Yes — approved end‑jointed lumber may be used interchangeably with solid‑sawn members of the same species and grade. If the assembly requires a fire‑resistance rating, the grade mark must include “Heat Resistant Adhesive” or “HRA” — § 2303.1.1.2.
What agency standards must panels conform to?
Wood structural panels used structurally must conform to DOC PS 1, DOC PS 2 or ANSI/APA PRP 210 and be identified by a trademark/grade mark showing grade, bond and Performance Category — § 2303.1.5.
Are there special marking rules for preservative‑ or fire‑retardant‑treated wood?
Yes. Preservative‑treated and fire‑retardant‑treated wood have additional identification and testing/strength‑adjustment requirements elsewhere in Chapter 23 and in the Residential Code (e.g., labeling requirements and strength adjustments); those provisions must be consulted in addition to §§ 2303.1.1 and 2303.1.5. The CBC excerpts retrieved reference these further rules but do not reproduce all label formats.
More in California Building Code
- Administration & Permits
- Energy Efficiency
- Existing Buildings
- Occupancy Classification & Use
- Hazardous Materials & Occupancies
- Types of Construction
- Fire-Resistance & Fire Safety
- Interior Finishes
- Means of Egress
- Accessibility
- Exterior Walls
- Roofing & Roof Assemblies
- Structural Design
- Special Inspections & Tests
- Foundations & Soils
- Concrete
- Masonry
- Steel
- Wood
- Elevators & Conveying Systems
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