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Chapter 4 — FOUNDATIONS

Section R407

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.

R407.1 Wood column protection.

Wood columns shall be protected against decay as set forth in Section R317.

R407.2 Steel column protection.

All surfaces (inside and outside) of steel columns shall be given a shop coat of rustinhibitive paint, except for corrosion-resistant steel and steel treated with coatings to provide corrosion resistance.

R407.3 Structural requirements.

The columns shall be restrained to prevent lateral displacement at the bottom end. Wood columns shall be not less in nominal size than 4 inches by 4 inches (102 mm by 102 mm). Steel columns shall be not

TABLE R405.1 PROPERTIES OF SOILS CLASSIFIED ACCORDING TO THE UNIFIED SOIL CLASSIFICATION SYSTEM

SOIL GROUP UNIFIED SOIL
CLASSIFICATION
SYSTEM SYMBOL		 SOIL DESCRIPTION DRAINAGE
CHARACTERISTICSa		 FROST HEAVE
POTENTIAL		 VOLUME CHANGE
POTENTIAL
EXPANSIONb
Group I GW Well-graded gravels, gravel sand mixtures, little or
no fines		 Good Low Low
Group I GP Poorly graded gravels or gravel sand mixtures, little
or no fines		 Good Low Low
Group I SW Well-graded sands, gravelly sands, little or no fines Good Low Low
Group I SP Poorly graded sands or gravelly sands, little or no
fines		 Good Low Low
Group I GM Silty gravels, gravel-sand-silt mixtures Good Medium Low
Group I SM Silty sand, sand-silt mixtures Good Medium Low
Group II GC Clayey gravels, gravel-sand-clay mixtures Medium Medium Low
Group II SC Clayey sands, sand-clay mixture Medium Medium Low
Group II ML Inorganic silts and very fine sands, rock flour, silty or
clayey fine sands or clayey silts with slight plasticity		 Medium High Low
Group II CL Inorganic clays of low to medium plasticity, gravelly
clays, sandy clays, silty clays, lean clays		 Medium Medium Medium to Low
Group III CH Inorganic clays of high plasticity, fat clays Poor Medium High
Group III MH Inorganic silts, micaceous or diatomaceous fine
sandy or silty soils, elastic silts		 Poor High High
Group IV OL Organic silts and organic silty clays of low plasticity Poor Medium Medium
Group IV OH Organic clays of medium to high plasticity, organic
silts		 Unsatisfactory Medium High
Group IV Pt Peat and other highly organic soils Unsatisfactory Medium High

For SI: 1 inch = 25.4 mm. a. The percolation rate for good drainage is over 4 inches per hour, medium drainage is 2 inches to 4 inches per hour, and poor is less than 2 inches per hour. b. Soils with a low potential expansion typically have a plasticity index (PI) of 0 to 15, soils with a medium potential expansion have a PI of 10 to 35 and soils

with a high potential expansion have a PI greater than 20.

4-46 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.

less than 3-inch-diameter (76 mm) Schedule 40 pipe manufactured in accordance with ASTM A53/A53M Grade B or approved equivalent.

Exception: In Seismic Design Categories A, B and C, columns not more than 48 inches (1219 mm) in height on a pier or footing are exempt from the bottom end lateral displacement requirement within under-floor areas enclosed by a continuous foundation.

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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
  14. ▸Chapter 4 — FOUNDATIONS
    Overview
    1. Section R401
    2. Section R402
    3. Section R403
    4. Section R404
    5. Section R405
    6. Section R406
    7. Section R407
    8. Section R408
  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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