CRC · California Residential Code
Foundations
Chapter 4 of the California Residential Code prescribes the design and construction rules for foundations — footings, walls, drainage, waterproofing and anchorage.
Last reviewed: July 6, 2026
Overview
Chapter 4 of the California Residential Code sets the prescriptive and material requirements for residential foundations — including footings, foundation walls (cast‑in‑place, masonry, wood and precast), columns, crawlspace/under‑floor spaces, drainage, dampproofing and waterproofing — and explains when soil tests and engineered design are required . The chapter is written to ensure foundations safely transfer building loads to the supporting soil while addressing moisture, drainage, frost protection and pest/decay resistance .
Key sections in Chapter 4 include §R401 (General), §R402 (Materials), §R403 (Footings), §R404 (Foundation and Retaining Walls), §R405 (Foundation Drainage) and §R406 (Waterproofing/Dampproofing) — these are the primary rules you’ll consult for foundation layout, minimum footing sizes, anchorage, drainage and wall construction details . For example, footing requirements and minimum dimensions are in §R403 (including Table R403.1(1)) and anchorage and seismic details are in §R403.1 and related sections; foundation wall thickness, reinforcement and special provisions for precast or wood foundations appear in §R404; drainage requirements are in §R405 .
In this section
Code references
Grounded in the retrieved California Residential Code — click a citation to read the verbatim passage:
CRC § 3-82 High relevance — show source text
R336 Large Family Day-Care Homes . . . . . . . . . . . . . . . . . . . 3-82
R337 Materials and Construction Methods for Exterior
Wildfire Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-83
R338 Electric Vehicle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-83
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CONTENTS
R339 Reserved . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-84
R340 Pollutant Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-84
CHAPTER 4 FOUNDATIONS . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
R401 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
R402 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5
R403 Footings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6
R404 Foundation and Retaining Walls . . . . . . . . . . . . . . . . 4-24
R405 Foundation Drainage . . . . . . . . . . . . . . . . . . . . . . . . . . 4-42
R406 Foundation Waterproofing and Dampproofing . . . 4-43
R407 Columns. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-44
R408 Under-Floor Space . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-44
CHAPTER 5 FLOORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3
R501 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3
R502 Wood Floor Framing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3
R503 Floor Sheathing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-12
R504 Pressure Preservative-Treated Wood
CRC § 4.1.1 High relevance — show source text
2||||X|||||||||||||||||||| |R401.4.1.1 through
R401.4.1.1.5||||X|||||||||||||||||||| |R404.5.1||||X|||||||||||||||||||| |R408.3||||X|||||||||||||||||||| |R408.4||||X|||||||||||||||||||| |R408.8||||||||||||||||||||X||||The state agency does not adopt sections identified with the following symbol: †
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4 FOUNDATIONS
User notes:
About this chapter: Chapter 4 provides requirements for constructing footings and walls for foundations of wood, masonry, concrete and precast concrete. In addition to a foundation’s ability to support the required design loads, this chapter addresses several other factors that can affect foundation performance. These include controlling surface water and subsurface drainage, requiring soil tests where conditions warrant and evaluating proximity to slopes and minimum depth requirements. This chapter also provides requirements to minimize adverse effects of moisture, decay and pests in basements and crawl spaces.
SECTION R401—GENERAL
R401.1 Application. The provisions of this chapter shall control the design and construction of the foundation and foundation spaces for buildings. In addition to the provisions of this chapter, the design and construction of foundations in flood hazard areas as established by Table R301.2 shall meet the provisions of Section R306. Wood foundations shall be designed and installed in accordance with AWC PWF.
Exception: The provisions of this chapter shall be permitted to be used for wood foundations only in the following situations:
- In buildings that have not more than two floors and a roof.
- Where interior basement and foundation walls are constructed at intervals not exceeding 50 feet (15 240 mm) .
Wood foundations in Seismic Design Category D 0, D 1 or D 2 shall be designed in accordance with accepted engineering practice.
R401.2 Requirements. Foundation construction shall be capable of accommodating all loads in accordance with Section R301 and of transmitting the resulting loads to the supporting soil. Fill soils that support footings and foundations shall be designed, installed and tested in accordance with accepted engineering practice.
Note: See Section R301.1.1.1 for limited-density owner-built rural dwellings.
R401.3 Drainage. Surface drainage shall be diverted to a storm sewer conveyance or other approved point of collection that does not create a hazard. Lots shall be graded to drain surface water away from foundation walls. The grade shall fall not fewer than 6 inches (152 mm) within the first 10 feet (3048 mm).
Exception: Where lot lines, walls, slopes or other physical barriers prohibit 6 inches (152 mm) of fall within 10 feet (3048 mm), drains or swales shall be constructed to ensure drainage away from the structure. Impervious surfaces within 10 feet (3048 mm) of the building foundation shall be sloped not less than 2 percent away from the building.
**R401.4 Soil tests.
CRC § 2.4 High relevance — show source text
Framing members that are both load-bearing and stabilization members shall meet the requirements of Section R602 and this section. Nonstructural stabilization members shall be not more than 32 inches (813 mm) on center. 2. Horizontal stabilization shall be installed at not more than 24 inches (610 mm) on center and in accordance with Figure BI103.2.4(1), BI103.2.4(2) or BI103.2.4(3). Horizontal stabilization shall be of any of the following with the stated minimum dimensions: [3] / 4 -inch (19.1 mm) bamboo, [1] / 2 -inch (12.7 mm) fiberglass rod, 1-inch (25 mm) wood dowel or nominal 1-inch by 2-inch (25 mm by 51 mm) wood.
FIGURE BI103.2.4(1)—LIGHT STRAW-CLAY WALL WITH LARSEN TRUSSES
DOUBLE TOP PLATE
VERTICAL SOLID BLOCKING
FLAT SOLID BLOCKING
LADDER (LARSEN) TRUSSES MADE WITH 2x4s AND GUSSETS PER SECTION BI103.2.4, ITEM 1
GUSSETS: [3] / 8 ″ x 3 ″ PLYWOOD OR 1x4 FASTENERS: 4–4d NAILS OR 4–1¾ ″ STAPLES
WOOD OR METAL STRAP BRACING (LIB) PER TABLE 602.10.4 WHERE APPLICABLE PER SECTION R602.10
LIGHT STRAW-CLAY INFILL
HORIZONTAL STABILIZATION OF LIGHT STRAW-CLAY PER SECTION BI103.4, ITEM 2
ANCHORAGE PER SECTION R403.1.6
2X SILL PLATE
CONCRETE OR MASONRY FOUNDATION PER SECTION R401
FRAMING FASTENERS PER TABLE R602.3(1)
For SI: 1 inch = 25.4 mm.
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APPENDIX BI — LIGHT STRAW-CLAY CONSTRUCTION
FIGURE BI103.2.4(2)—LIGHT STRAW-CLAY WALL, SINGLE STUD WIDTH
DOUBLE TOP PLATE
FLAT SOLID BLOCKING
WOOD METAL STRAP BRACING (LIB) PER TABLE R602.10.4 WHERE APPLICABLE PER SECTION R602.10
2X STUDS PER SECTION BI103.2.4, ITEM 1
1x1 CLEAT CENTERED ON EACH STUD FACE BETWEEN HORIZONTAL STABILIZATION
HORIZONTAL STABILIZATION OF LIGHT STRAW-CLAY PER SECTION BI103.2.4, ITEM 2
LIGHT STRAY-CLAY INFILL
ANCHORAGE PER SECTION R403.1.6
2X SILL PLATE
CONCRETE OR MASONRY FOUNDATION PER SECTION R401
FRAMING FASTENERS PER TABLE R602.3(1)
FIGURE BI103.2.4(3)—LIGHT STRAW-CLAY WALL WITH BLIND STUDS
DOUBLE TOP PLATES
2X LET-IN PLATE
WOOD METAL BRACING (LIB) PER TABLE R602.10.4 WHERE APPLICABLE PER SECTION R602.10
2x6 MINIMUM STUDS PER SECTION BI103.2.4, ITEM 1
LIGHT STRAW-CLAY INFILL
CRC § 25.4 High relevance — show source text
CONCRETE OR MASONRY FOUNDATION PER SECTION R401
FRAMING FASTENERS PER TABLE R602.3(1)
For SI: 1 inch = 25.4 mm.
APPENDIX BI-4 2025 CALIFORNIA RESIDENTIAL CODE
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APPENDIX BI — LIGHT STRAW-CLAY CONSTRUCTION
FIGURE BI103.2.4(2)—LIGHT STRAW-CLAY WALL, SINGLE STUD WIDTH
DOUBLE TOP PLATE
FLAT SOLID BLOCKING
WOOD METAL STRAP BRACING (LIB) PER TABLE R602.10.4 WHERE APPLICABLE PER SECTION R602.10
2X STUDS PER SECTION BI103.2.4, ITEM 1
1x1 CLEAT CENTERED ON EACH STUD FACE BETWEEN HORIZONTAL STABILIZATION
HORIZONTAL STABILIZATION OF LIGHT STRAW-CLAY PER SECTION BI103.2.4, ITEM 2
LIGHT STRAY-CLAY INFILL
ANCHORAGE PER SECTION R403.1.6
2X SILL PLATE
CONCRETE OR MASONRY FOUNDATION PER SECTION R401
FRAMING FASTENERS PER TABLE R602.3(1)
FIGURE BI103.2.4(3)—LIGHT STRAW-CLAY WALL WITH BLIND STUDS
DOUBLE TOP PLATES
2X LET-IN PLATE
WOOD METAL BRACING (LIB) PER TABLE R602.10.4 WHERE APPLICABLE PER SECTION R602.10
2x6 MINIMUM STUDS PER SECTION BI103.2.4, ITEM 1
LIGHT STRAW-CLAY INFILL
HORIZONTAL STABILIZATION PER SECTION BI103.2.4, ITEM 2
2X BOTTOM PLATE
2X SILL PLATE
ANCHORAGE PER SECTION R403.1.6
CONCRETE OR MASONRY FOUNDATION PER SECTION R401
FRAMING FASTENERS PER TABLE R602.3(1)
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APPENDIX BI — LIGHT STRAW-CLAY CONSTRUCTION
BI103.3 Materials. The materials used in light straw-clay construction shall be in accordance with Sections BI103.3.1 through BI103.3.3.
BI103.3.1 Straw requirements. Straw shall be stems of wheat, rye, oats, rice or barley, and shall be free of visible decay, insects and green plant material.
BI103.3.2 Clay subsoil requirements. Suitability of clay subsoil shall be determined in accordance with Table BI103.2.3.
BI103.3.3 Light straw-clay mixture. A light straw-clay mixture shall consist of loose straw mixed and coated with clay slip such that there is not more than 5 percent uncoated straw, and shall be in accordance with Table BI103.2.3.
BI103.4 Wall construction. Light straw-clay wall construction shall be in accordance with the requirements of Sections BI103.4.1 through BI103.4.7.
BI103.4.1 Light straw-clay maximum thickness. The maximum thickness of light straw-clay shall be in accordance with Table BI103.2.3.
CRC § 2.4 Medium relevance — show source text
HORIZONTAL STABILIZATION PER SECTION BI103.2.4, ITEM 2
2X BOTTOM PLATE
2X SILL PLATE
ANCHORAGE PER SECTION R403.1.6
CONCRETE OR MASONRY FOUNDATION PER SECTION R401
FRAMING FASTENERS PER TABLE R602.3(1)
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APPENDIX BI — LIGHT STRAW-CLAY CONSTRUCTION
BI103.3 Materials. The materials used in light straw-clay construction shall be in accordance with Sections BI103.3.1 through BI103.3.3.
BI103.3.1 Straw requirements. Straw shall be stems of wheat, rye, oats, rice or barley, and shall be free of visible decay, insects and green plant material.
BI103.3.2 Clay subsoil requirements. Suitability of clay subsoil shall be determined in accordance with Table BI103.2.3.
BI103.3.3 Light straw-clay mixture. A light straw-clay mixture shall consist of loose straw mixed and coated with clay slip such that there is not more than 5 percent uncoated straw, and shall be in accordance with Table BI103.2.3.
BI103.4 Wall construction. Light straw-clay wall construction shall be in accordance with the requirements of Sections BI103.4.1 through BI103.4.7.
BI103.4.1 Light straw-clay maximum thickness. The maximum thickness of light straw-clay shall be in accordance with Table BI103.2.3.
BI103.4.2 Distance above grade. Light straw-clay and its exterior finish shall be not less than 8 inches (203 mm) above exterior finished grade.
BI103.4.3 Moisture barrier. An approved moisture barrier shall separate the bottom of light straw-clay walls from any masonry or concrete foundation or slab that directly supports the walls. Penetrations and joints in the barrier shall be sealed with an approved sealant.
BI103.4.4 Contact with wood members. Light straw-clay shall be permitted to be in contact with untreated wood members.
BI103.4.5 Contact with nonwood structural members. Nonwood structural members in contact with light straw-clay shall be resistant to corrosion or shall be coated to prevent corrosion with an approved coating.
BI103.4.6 Installation. Light straw-clay shall be installed in accordance with the following:
Formwork shall be sufficiently strong to resist bowing where the light straw-clay is compacted into the forms.
Light straw-clay shall be uniformly placed into forms and evenly tamped to achieve stable walls free of voids. Light straw-clay shall be placed in lifts of not more than 6 inches (152 mm) and shall be thoroughly tamped before additional material is added.
Temporary formwork shall be removed from walls within 24 hours after tamping, and walls shall remain exposed until moisture content is in accordance with Section BI103.5.1. Visible voids shall be filled with light straw-clay or other insulative material prior to plastering.
CRC § 4-19 Medium relevance — show source text
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FOUNDATIONS
FIGURE R403.3(4)—INSULATION PLACEMENT FOR FROST-PROTECTED FOOTINGS ADJACENT TO HEATED STRUCTURE
B
C
Col1 Col2 Col3 Col4 Col5 Col6 C C C C R403.3.1 Foundations adjoining frost-protected shallow foundations. Foundations that adjoin frost-protected shallow foundations shall be protected from frost in accordance with Section R403.1.4.
R403.3.1.1 Attachment to unheated slab-on-ground structure. Vertical wall insulation and horizontal insulation of frostprotected shallow foundations that adjoin a slab-on-ground foundation that does not have a monthly mean temperature maintained at not less than 64°F (18°C) shall be in accordance with Figure R403.3(3) and Table R403.3(1). Vertical wall insulation shall extend between the frost-protected shallow foundation and the adjoining slab foundation. Required horizontal insulation shall be continuous under the adjoining slab foundation and through any foundation walls adjoining the frostprotected shallow foundation. Where insulation passes through a foundation wall, it shall be either of a type complying with this section and having bearing capacity equal to or greater than the structural loads imposed by the building, or the building shall be designed and constructed using beams, lintels, cantilevers or other means of transferring building loads such that the structural loads of the building do not bear on the insulation.
R403.3.1.2 Attachment to heated structure. Where a frost-protected shallow foundation abuts a structure that has a monthly mean temperature maintained at not less than 64°F (18°C), horizontal insulation and vertical wall insulation shall not be required between the frost-protected shallow foundation and the adjoining structure. Where the frost-protected shallow foundation abuts the heated structure, the horizontal insulation and vertical wall insulation shall extend along the adjoining foundation in accordance with Figure R403.3(4) a distance of not less than Dimension A in Table R403.3(1).
Exception: Where the frost-protected shallow foundation abuts the heated structure to form an inside corner, vertical insulation extending along the adjoining foundation is not required.
R403.3.2 Protection of horizontal insulation below ground. Horizontal insulation placed less than 12 inches (305 mm) below the ground surface or that portion of horizontal insulation extending outward more than 24 inches (610 mm) from the foundation edge shall be protected against damage by use of a concrete slab or asphalt paving on the ground surface directly above the insulation or by cementitious board, plywood rated for below-ground use, or other approved materials placed below ground, directly above the top surface of the insulation.
R403.3.3 Drainage. Final grade shall be sloped in accordance with Section R401.3. In other than Group I Soils, as detailed in Table R401.4.1(2), gravel or crushed stone beneath horizontal insulation below ground shall drain to daylight or into an approved sewer system.
R403.3.4 Termite protection. The use of foam plastic in areas of “very heavy” termite infestation probability shall be in accordance with Section R305.4.
R403.4 Footings for precast concrete foundations. Footings for precast concrete foundations shall comply with Section R403.4.
CRC § 2.1 Medium relevance — show source text
See Section R402.2 for maximum cementitious materials content.
f. For garage floors with a steel-troweled finish, reduction of the total air content (percent by volume of concrete) to not less than 3 percent is permitted if the specified
compressive strength of the concrete is increased to not less than 4,000 psi.|R402.2.1 Materials for concrete. Materials for concrete shall comply with the requirements of Section R608.5.1.
R402.3 Precast concrete. Precast concrete foundations shall be designed in accordance with Section R404.5 and shall be installed in accordance with the provisions of this code and the manufacturer’s instructions.
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FOUNDATIONS
R402.3.1 Precast concrete foundation materials. Materials used to produce precast concrete foundations shall meet the following requirements:
All concrete used in the manufacture of precast concrete foundations shall have a minimum compressive strength of 5,000 psi (34 470 kPa) at 28 days. Concrete exposed to a freezing and thawing environment shall be air entrained with a minimum total air content of 5 percent.
Structural reinforcing steel shall meet the requirements of ASTM A615, A706M or A996M. The minimum yield strength of reinforcing steel shall be 40,000 psi (Grade 40) (276 MPa). Steel reinforcement for precast concrete foundation walls shall have a minimum concrete cover of [3] / 4 inch (19.1 mm).
Panel-to-panel connections shall be made with Grade II steel fasteners.
The use of nonstructural fibers shall conform to ASTM C1116.
Grout used for bedding precast foundations placed on concrete footings shall meet ASTM C1107.
R402.4 Masonry. Masonry systems shall be designed and installed in accordance with this chapter and shall have a minimum specified compressive strength of 1,500 psi (10.3 MPa).
SECTION R403—FOOTINGS
R403.1 General. All exterior walls shall be supported on continuous solid or fully grouted masonry or concrete footings, crushed stone footings, wood foundations, or other approved structural systems that shall be of sufficient design to accommodate all loads according to Section R301 and to transmit the resulting loads to the soil within the limitations as determined from the character of the soil. Footings shall be supported on undisturbed natural soils or engineered fill. Concrete footing shall be designed and constructed in accordance with the provisions of Section R403 or in accordance with ACI 332.
|TABLE R403.1(1)—MINIMUM WIDTH AND THICKNESS FOR
CONCRETE FOOTINGS FOR LIGHT-FRAME CONSTRUCTION (inches)a, b, c,CRC § 3.1 Medium relevance — show source text
Cold-formed steel framing shall be anchored directly to the foundation or fastened to wood sill plates in accordance with Section R505.3.1 or R603.3.1, as applicable. Wood sill plates supporting cold-formed steel framing shall be anchored to the foundation in accordance with this section.
Wood sole plates at all exterior walls on monolithic slabs, wood sole plates of braced wall panels at building interiors on monolithic slabs and all wood sill plates shall be anchored to the foundation with minimum [1] / 2 -inch-diameter (12.7 mm) anchor bolts spaced not greater than 6 feet (1829 mm) on center or approved anchors or anchor straps spaced as required to provide equivalent anchorage to [1] / 2 -inch-diameter (12.7 mm) anchor bolts. Bolts shall extend not less than 7 inches (178 mm) into concrete or grouted cells of concrete masonry units. The bolts shall be located in the middle third of the width of the plate. A nut and washer shall be tightened on each anchor bolt. There shall be not fewer than two bolts per plate section with one bolt located not more than 12 inches (305 mm) or less than seven bolt diameters from each end of the plate section. Interior bearing wall sole plates on monolithic slab foundation that are not part of a braced wall panel shall be positively anchored with approved fasteners. Sill plates and sole plates shall be protected against decay and termites where required by Sections R304 and R305. Anchor bolts shall be permitted to be located while concrete is still plastic and before it has set. Where anchor bolts resist placement or the consolidation of concrete around anchor bolts is impeded, the concrete shall be vibrated to ensure full contact between the anchor bolts and concrete.
Exceptions:
- Walls 24 inches (610 mm) total length or shorter connecting offset braced wall panels shall be anchored to the foundation with not fewer than one anchor bolt located in the center third of the plate section and shall be attached to adjacent braced wall panels at corners as shown in Item 9 of Table R602.3(1).
- Connection of walls 12 inches (305 mm) total length or shorter connecting offset braced wall panels to the foundation without anchor bolts shall be permitted. The wall shall be attached to adjacent braced wall panels at corners as shown in Item 9 of Table R602.3(1).
R403.1.6.1 Foundation anchorage in Seismic Design Categories C, D 0 , D 1 and D 2 . In addition to the requirements of Section R403.1.6, the following requirements shall apply to wood light-frame structures in Seismic Design Categories D 0, D 1 and D 2 and wood light-frame townhouses in Seismic Design Category C.
- Plate washers conforming to Section R602.11.1 shall be provided for all anchor bolts over the full length of required braced wall lines except where approved anchor straps are used. Properly sized cut washers shall be permitted for anchor bolts in wall lines not containing braced wall panels.
- Interior braced wall plates shall have anchor bolts spaced at not more than 6 feet (1829 mm) on center and located within 12 inches (305 mm) of the ends of each plate section where supported on a continuous foundation.
- Interior bearing wall sole plates shall have anchor bolts spaced at not more than 6 feet (1829 mm) on center and located within 12 inches (305 mm) of the ends of each plate section where supported on a continuous foundation.
CRC § 4-14 Medium relevance — show source text
Constructed in accordance with ASCE 32.
Erected on solid rock.
Footings shall not bear on frozen soil unless the frozen condition is permanent.
Exceptions:
- Protection of free-standing accessory structures with an area of 600 square feet (56 m [2] ) or less, of light-frame construction, with an eave height of 10 feet (3048 mm) or less shall not be required.
- Protection of free-standing accessory structures with an area of 400 square feet (37 m [2] ) or less, of other than lightframe construction, with an eave height of 10 feet (3048 mm) or less shall not be required.
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FOUNDATIONS
R403.1.5 Slope. The top surface of footings shall be level. The bottom surface of footings shall not have a slope exceeding 1 unit vertical in 10 units horizontal (10-percent slope). Footings shall be stepped where it is necessary to change the elevation of the top surface of the footings or where the slope of the bottom surface of the footings will exceed 1 unit vertical in 10 units horizontal (10percent slope).
R403.1.6 Foundation anchorage. Wood sill plates and wood walls supported directly on continuous foundations shall be anchored to the foundation in accordance with this section.
Cold-formed steel framing shall be anchored directly to the foundation or fastened to wood sill plates in accordance with Section R505.3.1 or R603.3.1, as applicable. Wood sill plates supporting cold-formed steel framing shall be anchored to the foundation in accordance with this section.
Wood sole plates at all exterior walls on monolithic slabs, wood sole plates of braced wall panels at building interiors on monolithic slabs and all wood sill plates shall be anchored to the foundation with minimum [1] / 2 -inch-diameter (12.7 mm) anchor bolts spaced not greater than 6 feet (1829 mm) on center or approved anchors or anchor straps spaced as required to provide equivalent anchorage to [1] / 2 -inch-diameter (12.7 mm) anchor bolts. Bolts shall extend not less than 7 inches (178 mm) into concrete or grouted cells of concrete masonry units. The bolts shall be located in the middle third of the width of the plate. A nut and washer shall be tightened on each anchor bolt. There shall be not fewer than two bolts per plate section with one bolt located not more than 12 inches (305 mm) or less than seven bolt diameters from each end of the plate section. Interior bearing wall sole plates on monolithic slab foundation that are not part of a braced wall panel shall be positively anchored with approved fasteners. Sill plates and sole plates shall be protected against decay and termites where required by Sections R304 and R305. Anchor bolts shall be permitted to be located while concrete is still plastic and before it has set. Where anchor bolts resist placement or the consolidation of concrete around anchor bolts is impeded, the concrete shall be vibrated to ensure full contact between the anchor bolts and concrete.
CRC § 5.2 Medium relevance — show source text
R404.5.2 Precast concrete foundation design drawings. Precast concrete foundation wall design drawings shall be submitted to the building official and approved prior to installation. Drawings shall include, at a minimum, the following information:
Design loading as applicable.
Footing design and material.
Concentrated loads and their points of application.
Soil bearing capacity.
Maximum allowable total uniform load.
Seismic design category.
Basic wind speed.
R404.5.3 Identification. Precast concrete foundation wall panels shall be identified by a certificate of inspection label issued by an approved third-party inspection agency.
SECTION R405 —FOUNDATION DRAINAGE
R405.1 Concrete or masonry foundations. Drains shall be provided around concrete or masonry foundations that retain earth and enclose habitable or usable spaces located below grade. Drainage tiles, gravel or crushed stone drains, perforated pipe or other approved systems or materials shall be installed at or below the top of the footing or below the bottom of the slab and shall discharge by gravity or mechanical means into an approved drainage system. Gravel or crushed stone drains shall extend not less than 1 foot (305 mm) beyond the outside edge of the footing and 6 inches (152 mm) above the top of the footing and be covered with an approved filter membrane material. The top of open joints of drain tiles shall be protected with strips of building paper. Except where otherwise recommended by the drain manufacturer, perforated drains shall be surrounded with an approved filter membrane or the filter membrane shall cover the washed gravel or crushed rock covering the drain. Drainage tiles or perforated pipe shall be placed on not less than 2 inches (51 mm) of washed gravel or crushed rock not less than one sieve size larger than the tile joint opening or perforation and covered with not less than 6 inches (152 mm) of the same material.
Exception: A drainage system is not required where the foundation is installed on well-drained ground or sand-gravel mixture soils according to the Unified Soil Classification System, Group I soils, as detailed in Table R401.4.1(2).
R405.1.1 Precast concrete foundation. Precast concrete walls that retain earth and enclose habitable or useable space located below-grade that rest on crushed stone footings shall have a perforated drainage pipe installed below the base of the wall on either the interior or exterior side of the wall, not less than 1 foot (305 mm) beyond the edge of the wall. If the exterior drainage pipe is used, an approved filter membrane material shall cover the pipe. The drainage system shall discharge into an approved sewer system or to daylight.
R405.2 Wood foundations. Wood foundations enclosing habitable or usable spaces located below grade shall be adequately drained in accordance with Sections R405.2.1 through R405.2.3.
R405.2.1 Base. A porous layer of gravel, crushed stone or coarse sand shall be placed to a minimum thickness of 4 inches (102 mm) under the basement floor. Provision shall be made for automatic draining of this layer and the gravel or crushed stone wall footings.
R405.2.2 Vapor retarder. A 6-mil-thick (0.15 mm) polyethylene vapor retarder shall be applied over the porous layer with the basement floor constructed over the polyethylene.
CRC § 3.3 Medium relevance — show source text
FIGURE R403.3(3)—INSULATION PLACEMENT FOR
FROST-PROTECTED FOOTINGS ADJACENT TO UNHEATED SLAB-ON-GROUND STRUCTURE
INSULATION DETAIL
FINISH GRADE OR CONCRETE
SLAB-ON-GRADE STRUCTURE
FROST-PROTECTED SHALLOW
FOUNDATION SLAB-ON-GRADE
FLOOR PER SECTION R403.3
12″ MAX. Col2 NOMINAL 4 SCREEN AND WASHED
DRAINED PER SECTION R403.3.3
C
BEAM LINTEL OR
CANTILEVER
TO CARRY LOAD
OVER NONLOAD
CONCRETE MASONRY OR
PERMANENT WOOD
FOUNDATION GRADE BEAM
OR WALL OF ADJACENT
UNHEATED STRUCTURE
FOOTING AS REQUIRED
Col1 Col2 Col3 Col4 Col5 Col6 Col7 Col8 Col9 C C C For SI: 1 inch = 25.4 mm.
a. See Table R403.3(1) for required dimensions and R -values for vertical and horizontal insulation.
2025 CALIFORNIA RESIDENTIAL CODE 4-19
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
FOUNDATIONS
FIGURE R403.3(4)—INSULATION PLACEMENT FOR FROST-PROTECTED FOOTINGS ADJACENT TO HEATED STRUCTURE
B
C
Col1 Col2 Col3 Col4 Col5 Col6 C C C C R403.3.1 Foundations adjoining frost-protected shallow foundations. Foundations that adjoin frost-protected shallow foundations shall be protected from frost in accordance with Section R403.1.4.
R403.3.1.1 Attachment to unheated slab-on-ground structure. Vertical wall insulation and horizontal insulation of frostprotected shallow foundations that adjoin a slab-on-ground foundation that does not have a monthly mean temperature maintained at not less than 64°F (18°C) shall be in accordance with Figure R403.3(3) and Table R403.3(1). Vertical wall insulation shall extend between the frost-protected shallow foundation and the adjoining slab foundation. Required horizontal insulation shall be continuous under the adjoining slab foundation and through any foundation walls adjoining the frostprotected shallow foundation. Where insulation passes through a foundation wall, it shall be either of a type complying with this section and having bearing capacity equal to or greater than the structural loads imposed by the building, or the building shall be designed and constructed using beams, lintels, cantilevers or other means of transferring building loads such that the structural loads of the building do not bear on the insulation.
CRC § 3-73 Medium relevance — show source text
R326 Sanitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-73
R327 Toilet, Bath and Shower Spaces. . . . . . . . . . . . . . . . . 3-73
R328 Aging-in-Place Design and Fall Prevention . . . . . . . . 3-73
R329 Solar Energy Systems . . . . . . . . . . . . . . . . . . . . . . . . . . 3-74
R330 Energy Storage Systems . . . . . . . . . . . . . . . . . . . . . . . 3-76
R331 Stationary Engine Generators. . . . . . . . . . . . . . . . . . . 3-79
R332 Stationary Fuel Cell Power Systems . . . . . . . . . . . . . 3-79
R333 Reserved . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-79
R334 Construction Waste Reduction, Disposal and Recycling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-79
R335 Special Provisions for Licensed 24-Hour Care Facilities in a Group R-3.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-79
R336 Large Family Day-Care Homes . . . . . . . . . . . . . . . . . . . 3-82
R337 Materials and Construction Methods for Exterior
Wildfire Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-83
R338 Electric Vehicle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-83
2025 CALIFORNIA RESIDENTIAL CODE xxi
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
CONTENTS
R339 Reserved . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-84
R340 Pollutant Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-84
CHAPTER 4 FOUNDATIONS . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
R401 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
R402 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5
Frequently asked questions
What section covers minimum footing widths and thicknesses?
Minimum footing dimensions for light‑frame construction are prescribed in §R403 and summarized in Table R403.1(1); see Section R403.1 for general footing support, bearing and installation requirements .
Where are foundation drainage and waterproofing requirements found?
Drainage for concrete, masonry and precast foundations is set out in §R405; dampproofing and waterproofing requirements for basements, crawlspaces and below‑grade walls are in §R406 and related portions of Chapter 4 .
Do precast foundation walls need engineered drawings?
Yes — precast concrete foundation panels must be designed in accordance with accepted engineering practice and the design drawings submitted and approved by the building official as required in §R404.5.2 .
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