Chapter 18 — SOILS AND FOUNDATIONS

(Matrix Adoption Tables are nonregulatory, intended only as an aid to the code user.

See Chapter 1 for state agency authority and building applications.)

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	5	5	5	5	5	5	5	5
Adopt entire chapter	X												X
Adopt entire chapter as amended (amended sections listed below)				X	X						X	X			X
Adopt only those sections that are listed below
Chapter / Section
1801.1.1– 1801.1.3											X	X			X
1802.1				X
1803.1											X	X			X
1803.1.1– 1803.1.1.5				X
1803.2												X
1803.3.1											X	X			X
1803.5.4 Exception											X	X			X
1803.6											X	X			X
1803.7											X	X			X
1804.4.1				X
1805.2											X	X			X
1805.4.1, Exception 2				X
1805.4.3
1807.1.3											X	X			X
1807.1.4											X	X			X
1807.1.5 Exception											X	X			X
1807.1.6											X	X			X
1807.2											X	X			X
1807.2.2											X	X			X
1807.2.5											X	X			X
1808.8 Exception											X	X			X
Table 1808.8.1											X	X			X
1808.8.6											X	X			X
1809.3											X	X			X
1809.7											X	X			X
1809.8											X	X			X
1809.9											X	X			X
1809.12											X	X			X
1809.14											X	X			X
1810.3.1.5.1											X	B			X
1810.3.3.1.9 #3											X	B			X
1810.3.2.4											X	X			X
1810.3.5.3.3											X	X			X
1810.3.8 Exceptions											X	B			X
1810.3.8.3.3 Exception											X	X			X
1810.3.9.4.2.1											X	X			X
1810.3.10.4	X			X
1810.3.10.4.1											X	B			X
1810.3.11											X	X			X

(continued)

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.

CALIFORNIA BUILDING CODE – MATRIX ADOPTION TABLE

CHAPTER 18 – SOILS AND FOUNDATIONS—continued

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	5	5	5	5	5	5	5	5
Adopt entire chapter	X												X
Adopt entire chapter as amended (amended sections listed below)				X	X						X	X			X
Adopt only those sections that are listed below
Chapter / Section
1810.3.11.2 #3, Exception #2											X	B			X
1810.3.12 Exception											X	B			X
1810.4.1.5											X	X			X
1811											X	B			X
1812											X	B			X
1813											X	X			X

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. (A & B) – OSHPD (HCAI) delineates that OHSPD 2 is either designated as an OSHPD 2A or 2B. See Ch. 1, Div. I, Section 1.10 for additional information.

18-2 2022 CALIFORNIA BUILDING CODE

CHAPTER 18

SOILS AND FOUNDATIONS

User notes:

About this chapter: Chapter 18 provides criteria for geotechnical and structural considerations in the selection, design and installation of foundation systems to support the loads imposed by the structure above. This chapter includes requirements for soils investigation and site preparation for receiving a foundation, including the load-bearing values for soils and protection for the foundation from frost and water intru- sion. Section 1808 addresses the basic requirements for all foundation types while subsequent sections address foundation requirements that are specific to shallow foundations and deep foundations.

Code development reminder: Code change proposals to this chapter will be considered by the IBC–Structural Code Development Commit- tee during the 2022 (Group B) Code Development Cycle.

1809A.14 Pipes and trenches.¶

Unless otherwise recom- mended by the soils report, open or backfilled trenches paral- lel with a footing shall not be below a plane having a downward slope of 1 unit vertical to 2 units horizontal (50

SOILS AND FOUNDATIONS

1808 A .8.4 Protection of concrete. Concrete foundations shall be protected from freezing during depositing and for a period of not less than 5 days thereafter. Water shall not be allowed to flow through the deposited concrete.

1808 A .8.5 Forming of concrete. Concrete foundations are permitted to be cast against the earth where, in the opinion of the building official, soil conditions do not require formwork. Where formwork is required, it shall be in accordance with Section 26.11 of ACI 318.

1808 A .8.6 Seismic requirements. See Section 1905 A for additional requirements for foundations of structures assigned to Seismic Design Category D, E or F.

For structures assigned to Seismic Design Category D, E or F, provisions of Section 18.13 of ACI 318 shall apply where not in conflict with the provisions of Sections 1808 A through 1810 A .

1808 A .9 Vertical masonry foundation elements. Vertical masonry foundation elements that are not foundation piers as defined in Section 202 shall be designed as piers, walls or columns, as applicable, in accordance with TMS 402.

1812A.7 Monitoring of existing structures.¶

1. The contractor shall complete a written and photo- graphic log of all existing structures within 100 ft or three times depth of shoring, prior to construction. A

SOILS AND FOUNDATIONS

installed under the entire building/structure footprint and not under isolated foundation elements only. Design, construc- tion, testing and inspection shall satisfy the requirements of this code except as modified in Sections 1813A.2 through 1813A.5.

1813A.2 Geotechnical report.¶

The geotechnical report shall specify vibro stone column requirements to ensure uniformity in total and differential immediate settlement, long term set- tlement and earthquake induced settlement.

1. Soil compaction shall be in accordance with California Geological Survey (CGS) Special Publication 117A (SP-117A): Guidelines for Evaluating and Mitigating Seismic Hazard in California.

2. Area replacement ratio for the compaction elements and the basis of its determination shall be explained. Minimum factor of safety for soil compaction shall be in accordance with SP-117A.

3. Depth of soil compaction elements and extent beyond the footprint of structures/foundation shall be defined. Extent beyond the foundation shall be half the depth of the VSCs with a minimum of 10 ft or an approved alternative.

4. Minimum diameter and maximum spacing of soil com- paction elements shall be specified. VSCs shall not be less than 2 feet in diameter, and center to center spac- ing shall not exceed 8 feet.

5. The modulus of subgrade reactions for shallow founda- tions shall account for the presence of compaction ele- ments.

6. The modulus of subgrade reactions, long-term settle- ment and post-earthquake settlement shall be specified along with expected total and differential settlements for design.

7. The acceptance criteria for Friction Cone and Piezo- cone Penetration Testing in accordance with ASTM D5778 complemented by the standard penetration test (SPT) in accordance with ASTM D1586, if necessary, to verify soil improvement shall be specified.

8. The requirements for special inspection and observa- tion by the geotechnical engineer shall be specified.

9. A final verified report (FVR) documenting the installa- tion of the ground improvement system and confirming that the ground improvement acceptance criteria have been met shall be prepared by the geotechnical engi- neer and submitted to the enforcement agency for review and approval.

1813A.3 Shallow foundations.¶

VSCs under the shallow foun- dation shall be located symmetrically around the centroid of the footing or load.

1. There shall be a minimum of four stone columns under each isolated or continuous/combined footing or approved equivalent.

2. The VSCs shall not be used to resist tension or over- turning uplift from the shallow foundations.

3. The foundation design for the shallow foundation shall consider the increased vertical stiffness of the VSCs as point supports for analysis, unless it is substantiated that the installation of the VSCs result in improvement of the surrounding soils such that the modulus of sub- grade reaction, long term settlement and post-earth- quake settlement can be considered uniform throughout.

1813A.4 Installation.¶

VSCs shall be installed with vibratory probes. Vertical columns of compacted unbounded aggregate shall be formed through the soils to be improved by adding gravel near the tip of the vibrator and progressively raising and repenetrating the vibrator which will results in the gravel being pushed into the surrounding soil. Gravel aggregate for VSCs shall be well graded with a maximum size of 6 inches and not more than 10 percent smaller than ³ /8 inch after com- paction.

1813A.5 Construction documents.¶

Construction documents for VSCs, as a minimum, shall include the following:

1. Size, depth and location of VSCs.

2. Extent of soil improvements along with building/struc- ture foundation outlines.

3. Field verification requirements and acceptance criteria using CPT/SPT.

4. The locations where CPT/SPT shall be performed.

5. The testing, inspection and observation (TIO) program shall indicate the inspection and observation required for the VSCs.

6. A note indicating foundation construction shall not commence until the final verified report specified in Section 1813A.2 Item 9 has been submitted to and approved by the enforcement agency.

18A-30 2022 CALIFORNIA BUILDING CODE

CALIFORNIA BUILDING CODE – MATRIX ADOPTION TABLE