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Chapter 16 — STRUCTURAL DESIGN

Section 1610 — SOIL LOADS AND HYDROSTATIC PRESSURE

2025 California Building Code (Title 24, Part 2) · 2025 edition · updated 2026-07-29 · California

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

1610.1 Lateral pressures.

Structures below grade shall be designed to resist lateral soil loads from adjacent soil. Soil loads specified in Table 1610.1 shall be used as the minimum design lateral soil loads unless determined otherwise by a geotechnical investigation in accordance with Section 1803. Foundation walls and other walls in which horizontal movement is restricted at the top shall be designed for at-rest pressure. Walls that are free to move and rotate at the top, such as retaining walls, shall be permitted to be designed for active pressure.

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

STRUCTURAL DESIGN

Where applicable, lateral pressure from fixed or moving surcharge loads shall be added to the lateral soil load. Lateral pressure shall be increased if expansive soils are present at the site. Foundation walls shall be designed to support the weight of the full hydrostatic pressure of undrained backfill unless a drainage system is installed in accordance with Sections 1805.4.2 and 1805.4.3.

Exception: Foundation walls extending not more than 8 feet (2438 mm) below grade and laterally supported at the top by flexible diaphragms shall be permitted to be designed for active pressure.

TABLE 1610.1—LATERAL SOIL LOAD

DESCRIPTION OF BACKFILL MATERIALc UNIFIED SOIL
CLASSIFICATION		 DESIGN LATERAL SOIL LOADa
(pound per square foot per foot of depth)		 DESIGN LATERAL SOIL LOADa
(pound per square foot per foot of depth)
DESCRIPTION OF BACKFILL MATERIALc UNIFIED SOIL
CLASSIFICATION		 Active pressure At-rest pressure
Well-graded, clean gravels; gravel-sand mixes GW 30 60
Poorly graded clean gravels; gravel-sand mixes GP 30 60
Silty gravels, poorly graded gravel-sand mixes GM 40 60
Clayey gravels, poorly graded gravel-and-clay mixes GC 45 60
Well-graded, clean sands; gravelly sand mixes SW 30 60
Poorly graded clean sands; sand-gravel mixes SP 30 60
Silty sands, poorly graded sand-silt mixes SM 45 60
Sand-silt clay mix with plastic fines SM-SC 45 100
Clayey sands, poorly graded sand-clay mixes SC 60 100
Inorganic silts and clayey silts ML 45 100
Mixture of inorganic silt and clay ML-CL 60 100
Inorganic clays of low to medium plasticity CL 60 100
Organic silts and silt clays, low plasticity OL Note b Note b
Inorganic clayey silts, elastic silts MH Note b Note b
Inorganic clays of high plasticity CH Note b Note b
Organic clays and silty clays OH Note b Note b
For SI: 1 pound per square foot per foot of depth = 0.157 kPa/m, 1 foot = 304.8 mm.
a. Design lateral soil loads are given for moist conditions for the specified soils at their optimum densities. Actual field conditions shall govern. Submerged or saturated soil pres-
sures shall include the weight of the buoyant soil plus the hydrostatic loads.
b. Unsuitable as backfill material.
c. The definition and classification of soil materials shall be in accordance with ASTM D2487.

1610.2 Uplift loads on floor and foundations.

Basement floors, slabs on ground, foundations, and similar approximately horizontal elements below grade shall be designed to resist uplift loads where applicable. The upward pressure of water shall be taken as the full hydrostatic pressure applied over the entire area. The hydrostatic load shall be measured from the underside of the element being evaluated. The design for upward loads caused by expansive soils shall comply with Section 1808.6.

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▸ Contents — 2025 California Building Code (Title 24, Part 2)
2025 California Building Code (Title 24, Part 2)
  1. Chapter 1 — ADMINISTRATION
  2. Chapter 2 — DEFINITIONS
  3. Chapter 3 — OCCUPANCY CLASSIFICATION AND USE
  4. Chapter 4 — SPECIAL DETAILED REQUIREMENTS BASED ON OCCUPANCY A…
  5. Chapter 5 — GENERAL BUILDING HEIGHTS AND AREAS
  6. Chapter 6 — TYPES OF CONSTRUCTION
  7. Chapter 7 — FIRE AND SMOKE PROTECTION FEATURES
  8. Chapter 7A — MATERIALS AND CONSTRUCTION METHODS FOR EXTERIOR W…
  9. Chapter 8 — INTERIOR FINISHES
  10. Chapter 9 — FIRE PROTECTION AND LIFE SAFETY SYSTEMS
  11. Chapter 10 — MEANS OF EGRESS
  12. Chapter 11 — RESERVED
  13. Chapter 11A — HOUSING ACCESSIBILITY
  14. Chapter 11B — ACCESSIBILITY TO PUBLIC BUILDINGS, PUBLIC ACCOMM…
  15. Chapter 12 — INTERIOR ENVIRONMENT
  16. Chapter 13 — ENERGY EFFICIENCY
  17. Chapter 14 — EXTERIOR WALLS
  18. Chapter 15 — ROOF ASSEMBLIES AND ROOFTOP STRUCTURES
  19. ▸ Chapter 16 — STRUCTURAL DESIGN
    Overview
    1. Section 1601 — GENERAL
    2. Section 1602 — NOTATIONS
    3. Section 1603 — CONSTRUCTION DOCUMENTS
    4. Section 1604 — GENERAL DESIGN REQUIREMENTS
    5. Section 1605 — LOAD COMBINATIONS
    6. Section 1606 — DEAD LOADS
    7. Section 1607 — LIVE LOADS
    8. Section 1608 — SNOW LOADS
    9. Section 1609 — WIND LOADS
    10. Section 1610 — SOIL LOADS AND HYDROSTATIC PRESSURE
    11. Section 1611 — RAIN LOADS
    12. Section 1612 — FLOOD LOADS
    13. Section 1613 — EARTHQUAKE LOADS
    14. Section 1614 — ATMOSPHERIC ICE LOADS
    15. Section 1615 — TSUNAMI LOADS
    16. Section 1616 — STRUCTURAL INTEGRITY
    17. Section 1617 — ADDITIONAL REQUIREMENTS FOR COMMUNITY COLLEGES …
  20. Chapter 16A — STRUCTURAL DESIGN
  21. Chapter 17 — SPECIAL INSPECTIONS AND TESTS
  22. Chapter 17A — SPECIAL INSPECTIONS AND TESTS
  23. Chapter 18 — SOILS AND FOUNDATIONS
  24. Chapter 18A — SOILS AND FOUNDATIONS
  25. Chapter 19 — CONCRETE
  26. Chapter 19A — CONCRETE
  27. Chapter 20 — ALUMINUM
  28. Chapter 21 — MASONRY
  29. Chapter 21A — MASONRY
  30. Chapter 22 — STEEL
  31. Chapter 22A — STEEL
  32. Chapter 23 — WOOD
  33. Chapter 24 — GLASS AND GLAZING
  34. Chapter 25 — GYPSUM PANEL PRODUCTS AND PLASTER
  35. Chapter 26 — PLASTIC
  36. Chapter 27 — ELECTRICAL
  37. Chapter 28 — MECHANICAL SYSTEMS
  38. Chapter 29 — PLUMBING SYSTEMS
  39. Chapter 30 — ELEVATORS AND CONVEYING SYSTEMS
  40. Chapter 31 — SPECIAL CONSTRUCTION
  41. Chapter 31A — SYSTEMS FOR WINDOW CLEANING OR EXTERIOR BUILDING…
  42. Chapter 31B — PUBLIC POOLS
  43. Chapter 31C — RADIATION
  44. Chapter 31D — FOOD ESTABLISHMENTS
  45. Chapter 31F — MARINE OIL TERMINALS
  46. Chapter 32 — ENCROACHMENTS INTO THE PUBLIC RIGHT-OF-WAY
  47. Chapter 33 — SAFEGUARDS DURING CONSTRUCTION
  48. Chapter 34 — RESERVED
  49. Chapter 35 — REFERENCED STANDARDS
  50. Appendix A — EMPLOYEE QUALIFICATIONS
  51. Appendix B — BOARD OF APPEALS
  52. Appendix C — GROUP U—AGRICULTURAL BUILDINGS
  53. Appendix D — FIRE DISTRICTS
  54. Appendix E — RESERVED
  55. Appendix F — RODENTPROOFING
  56. Appendix G — FLOOD-RESISTANT CONSTRUCTION
  57. Appendix H — SIGNS
  58. Appendix I — PATIO COVERS
  59. Appendix J — GRADING
  60. Appendix K — GROUP R-3 AND GROUP R-3.1 OCCUPANCIES PROTECTED B…
  61. Appendix L — EARTHQUAKE RECORDING INSTRUMENTATION
  62. Appendix M — TSUNAMI-GENERATED FLOOD HAZARDS
  63. Appendix N — REPLICABLE BUILDINGS
  64. Appendix O — PERFORMANCE-BASED APPLICATION
  65. Appendix P — SLEEPING LOFTS
  66. Appendix Q — EMERGENCY HOUSING

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