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Appendix C — GUIDELINES FOR THE WIND RETROFIT OF EXISTING BUILDINGS

Section C202 — ROOF DECK ATTACHMENT FOR WOOD ROOFS

2025 California Existing Building Code (Title 24, Part 10) · 2025 edition · updated 2026-07-27 · California

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

[BS] C202.1 Roof decking attachment for one- and two-family dwellings. For one- and two-family dwellings, fastening shall be in accordance with Section C202.1.1 or C202.1.2 as appropriate for the existing construction. The diameter of 8d nails shall be not less than 0.131 inch (3 mm) and the length shall be not less than 2 [1] / 4 inches (57 mm) to qualify for the provisions of this section for existing nails regardless of head shape or head diameter.

[BS] C202.1.1 Sawn lumber or wood plank roofs. Roof decking consisting of sawn lumber or wood planks up to 12 inches (30 cm) wide and secured with not fewer than two nails (minimum size 8d) to each roof framing member it crosses shall be deemed to be sufficiently connected. Sawn lumber or wood plank decking secured with smaller fasteners than 8d nails or with fewer than two nails (minimum size 8d) to each framing member it crosses shall be deemed sufficiently connected if fasteners are added such that two clipped head, round head or ring shank nails (minimum size 8d) are in place on each framing member the nail crosses.

[BS] C202.1.2 Wood structural panel roofs For roof decking consisting of wood structural panels, fasteners and spacings required in Table C202.1.2 shall be deemed to comply with the requirements of Section 706.3.

Supplemental fasteners as required by Table C202.1.2 shall be 8d ring shank nails with round heads and the following minimum dimensions:

  1. 0.113-inch-nominal (3 mm) shank diameter.
  2. Ring diameter not less than 0.012 inch (0.3 mm) greater than shank diameter.
  3. 16 to 20 rings per inch.
  4. A minimum 0.280-inch (7 mm) full round head diameter.
  5. Ring shank to extend not less than 1 [1] / 2 inches (38 mm) from the tip of the nail.
  6. Minimum 2 [1] / 4 -inch (57 mm) nail length.

[BS] TABLE C202.1.2—SUPPLEMENT FASTENERS AT PANEL EDGES AND INTERMEDIATE FRAMING

EXISTING FASTENERS EXISTING FASTENER
SPACING (EDGE OR
INTERMEDIATE
SUPPORTS)		 MAXIMUM
SUPPLEMENTAL
FASTENER SPACING
FOR
130 MPH <****Vult ≤ 140 MPH		 MAXIMUM SUPPLEMENTAL
FASTENER SPACING FOR
INTERIOR ZONEc LOCATIONS
FOR MPHVult > 140 MPH AND
EDGE ZONES NOT COVERED
BY THE COLUMN TO THE
RIGHT		 EDGE ZONEd FOR
Vult > 160 MPH AND EXPOSURE C,
OR
Vult > 180 MPH AND EXPOSURE B
Staples or 6d Any 6″ o.c.b 6″ o.c.b 4″ o.c.b at panel edges and
4″ o.c.b at intermediate supports
8d clipped head or
round head smooth
shank		 6″ o.c. or less None necessary None necessary along edges of
panels but 6″ o.c.b at interme-
diate supports of panel		 4″ o.c.a at panel edges and
4″ o.c.a at intermediate supports
8d clipped head or
round head ring shank		 6″ o.c. or less None necessary None necessary 4″ o.c.a at panel edges and
4″ o.c.a at intermediate supports
8d clipped head or
round head smooth
shank		 Greater than 6″ o.c. 6″ o.c.a 6″ o.c.a along panel edges and
6″ o.c.b at intermediate
supports of panel		 4″ o.c.a at panel edges and
4″ o.c.a at intermediate supports
8d clipped head or
round head ring shank		 Greater than 6″ o.c. 6″ o.c.a 6″ o.c.a 4″ o.c.a at panel edges and
4″ o.c.a at intermediate supports
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 mile per hour = 0.447 m/s.
a. Maximum spacing determined based on existing fasteners and supplemental fasteners.
b. Maximum spacing determined based on supplemental fasteners only.
c. Interior zone = sheathing that is not located within 4 feet of the perimeter edge of the roof or within 4 feet of each side of a ridge.
d. Edge zone = sheathing that is located within 4 feet of the perimeter edge of the roof and within 4 feet of each side of a ridge.

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

APPENDIX C-28 2025 CALIFORNIA EXISTING BUILDING CODE

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

CALIFORNIA EXISTING BUILDING CODE – MATRIX ADOPTION TABLE

APPENDIX C

CHAPTER C3 – REFERENCED STANDARDS

Not adopted by the State of California (May be available for adoption by local ordinance. See Section 1.1.11.)

Adopting Agency BSC BSC-
CG		 SFM HCD DSA OSHPD BSCC DPH AGR DWR CEC CA SL SLC
Adopting Agency BSC BSC-
CG		 SFM 1 2 1/AC AC SS SS/CC 1 1R 2 3 4 5 6 6 6 6 6 6 6 6 6
Adopt Entire Chapter
Adopt Entire Chapter as
amended (amended
sections listed below)
Adopt only those sections
that are listed below
Chapter / Section

The state agency does not adopt sections identified with the following symbol: † The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

APPENDIX C-30 2025 CALIFORNIA EXISTING BUILDING CODE

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

APPENDIX C—GUIDELINES FOR THE WIND RETROFIT OF EXISTING BUILDINGS

CHAPTER C3

REFERENCED STANDARDS

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▸ Contents — 2025 California Existing Building Code (Title 24, Part 10)
2025 California Existing Building Code (Title 24, Part 10)
  1. 104.11 for consideration of alternative means of compliance.
  2. Chapter 1 — ADMINISTRATION
  3. Chapter 2 — DEFINITIONS
  4. Chapter 3 — PROVISIONS FOR ALL COMPLIANCE METHODS
  5. Chapter 3A — PROVISIONS FOR ALL COMPLIANCE METHODS
  6. Chapter 4 — REPAIRS
  7. Chapter 4A — REPAIRS
  8. Chapter 5 — PRESCRIPTIVE COMPLIANCE METHOD
  9. Chapter 5A — PRESCRIPTIVE COMPLIANCE METHOD
  10. Chapter 6 — CLASSIFICATION OF WORK
  11. Chapter 7 — ALTERATIONS—LEVEL 1
  12. Chapter 8 — ALTERATIONS—LEVEL 2
  13. Chapter 9 — ALTERATIONS—LEVEL 3
  14. Chapter 10 — CHANGE OF OCCUPANCY
  15. Chapter 11 — ADDITIONS
  16. Chapter 12 — HISTORIC BUILDINGS
  17. Chapter 13 — PERFORMANCE COMPLIANCE METHODS
  18. Chapter 14 — RELOCATED OR MOVED BUILDINGS
  19. Chapter 15 — CONSTRUCTION SAFEGUARDS
  20. Chapter 16 — REFERENCED STANDARDS
  21. Appendix A — GUIDELINES FOR THE SEISMIC RETROFIT OF EXISTING B…
  22. Appendix B — SUPPLEMENTARY ACCESSIBILITY REQUIREMENTS FOR EXIS…
  23. ▸ Appendix C — GUIDELINES FOR THE WIND RETROFIT OF EXISTING BUIL…
    Overview
    1. Section C101 — GENERAL
    2. Section C102 — DEFINITIONS
    3. Section C103 — MATERIALS OF CONSTRUCTION
    4. Section C104 — RETROFITTING GABLE END WALLS TO ENHANCE WIND RE…
    5. Section C201 — GENERAL
    6. Section C202 — ROOF DECK ATTACHMENT FOR WOOD ROOFS
    7. Section C301 — REFERENCED STANDARDS
  24. Appendix D — BOARD OF APPEALS
  25. Appendix E — TEMPORARY EMERGENCY USES
  26. Appendix A — GUIDELINES ON FIRE RATINGS OF ARCHAIC MATERIALS A…

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