CRC · California Residential Code

What are the design requirements for freestanding and retaining walls?

If your free‑standing yard wall is unsupported at the top and holds more than 48 inches of unbalanced soil (or is over 24 inches and resists extra lateral loads), the California Residential Code requires an engineered design to prevent overturning, sliding, excessive bearing and water uplift, and to meet a minimum safety factor of 1.5; foundation and drainage rules in related CRC sections also apply.

Ask a question free See coverage

Last reviewed: July 6, 2026

What the code requires — 2-4 sentences

The California Residential Code requires that a retaining wall that is not laterally supported at the top and that retains more than 48 inches (1219 mm) of unbalanced fill, or any retaining wall exceeding 24 inches (610 mm) in height that resists lateral loads in addition to soil, be designed by accepted engineering practice for stability (overturning, sliding, foundation pressure and water uplift) and for a safety factor of 1.5 against sliding and overturning. This requirement is stated in § R404.4.

If a wall is unsupported at the top and holds more than 48 inches of unbalanced soil (or is over 24 inches and resists additional lateral loads), it must be engineered to resist overturning, sliding, excessive foundation pressure and water uplift with a safety factor of 1.5.

Requirements in detail

Scope / when the rule applies

  • The rule applies to a retaining wall that is:
    • Not laterally supported at the top, and it retains > 48 in (1219 mm) of unbalanced backfill; OR
    • Any retaining wall > 24 in (610 mm) in height that resists lateral loads beyond soil loads (for example, surcharge or structure loads). § R404.4.
  • The section explicitly states it does not apply to foundation walls supporting buildings (those are covered elsewhere). § R404.4.

Mandatory performance outcomes

Design must ensure stability against:

  • Overturning
  • Sliding
  • Excessive foundation bearing pressure
  • Water uplift All designs must meet a safety factor of 1.5 for lateral sliding and overturning. § R404.4.

Relationship to foundation / concrete wall provisions

  • Concrete or masonry foundation walls that support more than 48 inches of unbalanced backfill or that are subject to hydrostatic pressure must be designed in accordance with the foundation wall provisions (see § R404.1.1 and § R404.1.3).
  • For concrete foundation walls, minimum reinforcement and cross-section rules are in § R404.1.3 and its tables; those provisions require lateral support at top and bottom and specific reinforcement when applicable.

Drainage and water control

  • Designs must address water (uplift and hydrostatic pressure). Foundation/retaining walls typically require drainage and dampproofing per § R405 and § R406 where applicable (foundation drainage and dampproofing provisions).

Key decision dimensions / values (code quick‑reference table)

Decision or threshold Required action / value Code Reference
Unbalanced fill height > 48 in (1219 mm) Wall must be engineered for stability (overturning, sliding, foundation pressure, water uplift) § R404.4
Wall height > 24 in (610 mm) that resists lateral loads in addition to soil Engineering design required § R404.4
Safety factor for sliding & overturning Minimum 1.5 (except where other specified exceptions apply) § R404.4
Foundation walls supporting buildings Different provisions; see foundation wall design requirements § R404.4 (exemption) and § R404.1.1
Drainage & dampproofing Provide drainage and dampproofing where walls retain earth and enclose habitable/usable spaces below grade § R405.1 (drainage) and § R406 (dampproofing)

What “designed in accordance with accepted engineering practice” means here

  • The code requires an engineered design for walls meeting the thresholds; it does not prescribe a single analysis method in § R404.4. Accepted practice generally includes:
    • Calculation of lateral earth pressures (including any surcharge),
    • Checks for overturning and sliding with required safety factors,
    • Bearing pressure checks on soils,
    • Consideration of groundwater (hydrostatic) loads and drainage measures.
  • For concrete/masonry foundation walls the CRC provides additional prescriptive reinforcement/section rules in § R404.1.3 and its tables when those provisions are used.

Exceptions & special cases

  • The R404.4 requirement explicitly does not apply to foundation walls supporting buildings — those are covered by separate foundation provisions (§ R404.1.1, § R404.1.3).
  • Some tables and notes in the foundation-wall sections require that walls retaining 4 ft (48 in) or more of unbalanced backfill be laterally supported at the top and bottom before backfilling (i.e., temporary lateral support during construction) — see the table notes in the foundation-wall tables.
  • Where concrete/masonry foundation walls fall within prescriptive applicability, the CRC gives specific minimum reinforcement and section dimensions (see § R404.1.3 and related tables), but when outside those limits a project-specific engineered design is required.

Common mistakes

  • Assuming any wall under 48 inches (or 24 inches) never needs engineering — the code distinguishes unbalanced backfill and also triggers engineering for walls >24 in that resist non‑soil lateral loads; always verify which threshold applies. § R404.4.
  • Measuring backfill height incorrectly — the CRC permits certain measurement rules (for example, interior slab elevation can be used for measuring unbalanced backfill in some tables); check the applicable table notes.
  • Ignoring groundwater or drainage — water uplift/hydrostatic pressure must be considered; drainage per § R405 is required where foundations/retaining walls retain earth and enclose habitable or usable spaces.
  • Treating foundation walls supporting buildings the same as freestanding retaining walls — foundation walls are covered by different provisions and may have different reinforcement/section requirements.
  • Failing to provide temporary lateral support during construction for walls that will retain 4 ft (48 in) or more before they are permanently laterally supported—see table notes.

Worked example — applying the rule (conceptual)

Scenario: A homeowner wants a freestanding yard wall that will retain a backfill with the finished exterior ground level 4.5 ft (54 in) above the base (unbalanced), and the wall will not be tied to a building.

  1. Code trigger: Because the wall retains more than 48 in (1219 mm) of unbalanced fill, § R404.4 requires an engineered design for stability (overturning, sliding, foundation pressure, water uplift) and a safety factor of 1.5. You cannot rely on simple masonry block stack‑up rules alone.

  2. Designer deliverables (typical, code‑driven):

    • Engineering calculations showing checks for overturning, sliding and bearing pressure, with results demonstrating ≥ 1.5 safety factor. § R404.4.
    • Details for groundwater control and drainage (drain tile, filter fabric, outlet) as required by § R405 if the wall retains earth adjoining habitable/usable below‑grade space.
    • Foundation/footing sizing and reinforcement details; if concrete foundation wall provisions are used, follow § R404.1.3 and the applicable tables for reinforcement and section dimensions.

  3. Construction note: If the wall will retain 4 ft (48 in) or more of unbalanced backfill during construction, temporary lateral support at top and bottom may be required before backfilling (refer to the foundation‑wall table notes).

This example demonstrates the decision points the code requires; the CRC does not prescribe a single analysis method in § R404.4 — use accepted engineering practice and provide stamped calculations/drawings where required by the jurisdiction.

Related provisions (CRC sections)

  • § R404.1.1 — Design required for foundation walls subject to hydrostatic pressure or supporting >48 in of unbalanced backfill.
  • § R404.1.3 — Concrete foundation wall design and minimum cross sections; see Table requirements and reinforcement provisions.
  • § R404.1.3.2 — Reinforcement requirements for foundation walls (horizontal/vertical rules and tables).
  • § R405 — Foundation drainage requirements (drain tile, filter material, discharge).
  • § R406 — Foundation dampproofing/waterproofing provisions (where applicable).
  • § R404.5 — Precast concrete foundation wall design and submittal requirements (relevant if precast panels are used).

Code references

Grounded in the retrieved California Residential Code — click a citation to read the verbatim passage:

  • CRC § 25.4 High relevance — show source text

    SP 30**|** GM, GC, SM,
    SM-SC and ML 45|     SC, ML-CL and**
    inorganic CL 60| |8|4|4 @ 48|4 @ 46|6 @ 39| |8|5|4 @ 45|5 @ 46|6 @ 47| |8|6|5 @ 45|6 @ 40|DR| |8|7|6 @ 44|DR|DR| |8|8|6 @ 32|DR|DR| |9|4|4 @ 48|4 @ 46|4 @ 37| |9|5|4 @ 42|5 @ 43|6 @ 44| |9|6|5 @ 41|6 @ 37|DR| |9|7|6 @ 39|DR|DR| |9|> 8|DRi|DR|DR| |10|4|4 @ 48|4 @ 46|4 @ 35| |10|5|4 @ 40|5 @ 40|6 @ 41| |10|6|5 @ 38|6 @ 34|DR| |10|7|6 @ 36|DR|DR| |10|> 8|DR|DR|DR| |For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot per foot = 0.1571 kPa2/m, 1 pound per square inch = 6.895 kPa.
    DR = Design Required.
    a. Soil classes are in accordance with the Unified Soil Classification System. Refer to Table R401.4.1(2).
    b. Table values are based on reinforcing bars with a minimum yield strength of 60,000 psi concrete with a minimum specified compressive strength of 2,500 psi and vertical rein-
    forcement being located at the centerline of the wall. See Section R404.1.3.3.7.2.
    c. Maximum spacings shown are the values calculated for the specified bar size. Where the bar used is Grade 60 and the size specified in the table, the actual spacing in the wall
    shall not exceed a whole-number multiple of 12 inches (12, 24, 36 and 48) that is less than or equal to the tabulated spacing. Vertical reinforcement with a yield strength of less
    than 60,000 psi and bars of a different size than specified in the table are permitted in accordance with Section R404.1.3.3.7.6 and Table R404.1.3.2(9).
    d. Deflection criterion is_L_/240, where_L_ is the height of the basement wall in inches.
    e. Interpolation is not permitted.
    f. Where walls will retain 4 feet or more of unbalanced backfill, they shall be laterally supported at the top and bottom before backfilling.
    g. See Section R404.1.3.2 for minimum reinforcement required for basement walls supporting above-grade concrete walls.
    h. See Table R608.3 for thicknesses and dimensions of waffle-grid walls.
    i. DR means design is required in accordance with the applicable building code, or in the absence of a code, in accordance with ACI 318.
    j.

  • CRC § 1.2 High relevance — show source text

    All cells shall be solidly filled with grout.

    Exception: Reinforced hollow unit masonry used for freestanding site walls or interior nonbearing nonshear wall partitions shall have horizontal reinforcing spaced not more than 4 feet (1.2 m) on center, except for locations in Seismic Design Category F, and may be grouted only in cells containing vertical and horizontal reinforcement.

    7.4.4.1.1 The minimum reinforcing shall be No. 4, except that No. 3 bars may be used for ties and stirrups. Vertical wall reinforce- ment shall have dowels of equal size and equally matched spacing in all footings. Reinforcement shall be continuous around wall corners and through intersections. Only reinforcement which is continuous in the wall shall be considered in computing the minimum area of reinforcement. Reinforcement with splices conforming to TMS 402 shall be considered as continuous reinforcement.

    7.4.4.1.2 Horizontal reinforcing bars in bond beams shall be provided in the top of footings, at the top of wall openings, at roof and floor levels, and at the top of parapet walls. For walls 12 inches (nominal) (305 mm) or more in thickness, horizontal and vertical reinforcement shall be equally divided into two layers, except where designed as retaining walls. Where reinforcement is added above the minimum requirements, such additional reinforcement need not be so divided.

    7.4.4.1.3 In bearing walls of every type of reinforced masonry, there shall be trim reinforcement of not less than one No. 5 bar or two No. 4 bars on all sides of, and adjacent to, every opening which exceeds 16 inches (406 mm) in either direction, and such bars shall extend not less than 48 diameters, but in no case less than 24 inches (610 mm) beyond the corners of the opening. The bars required by this paragraph shall be in addition to the minimum reinforcement required elsewhere.

    7.4.4.1.4 When the reinforcement in bearing walls is designed, placed and anchored in position as for columns, the allowable stresses shall be as for columns.

    7.4.4.1.5 Joint reinforcement shall not be used as principal reinforcement in masonry.

    2025 CALIFORNIA BUILDING CODE 21-7

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

    �

    �

    �

    MASONRY

    SECTION 2107—ALLOWABLE STRESS DESIGN

    2107.1 General. The design of masonry structures using allowable stress design shall comply with Section 2106 and the requirements of Chapters 1 through 8 of TMS 402 except as modified by Sections 2107.2 through 2107.3 [OSHPD 1R, 2 & 5] through 2107.5.

    2107.2 TMS 402, Section 6.1.7.1, lap splices. As an alternative to Section 6.1.7.1, it shall be permitted to design lap splices in accordance with Section 2107.2.1.

    2107.2.1 Lap splices. The minimum length of lap splices for reinforcing bars in tension or compression, l d, shall be: Equation 21-1 l d = 0.002 d b f s

  • CRC § 1807.1.6.3.2 High relevance — show source text

    1807.1.6.3.2 Seismic requirements. Based on the seismic design category assigned to the structure in accordance with Section 1613, masonry foundation walls designed using Tables 1807.2.5.

    1. Seismic Design Categories A and B. No additional seismic requirements.
    2. Seismic Design Category C. A design using Tables 1807.1.6.3(1) through 1807.1.6.3(4) is subject to the seismic requirements of Section 7.4.3 of TMS 402.
    3. Seismic Design Category D. A design using Tables 1807.1.6.3(2) through 1807.1.6.3(4) is subject to the seismic requirements of Section 7.4.4 of TMS 402.
    4. Seismic Design Categories E and F. A design using Tables 1807.1.6.3(2) through 1807.1.6.3(4) is subject to the seismic requirements of Section 7.4.5 of TMS 402.

    1807.2 Retaining walls. Retaining walls shall be designed in accordance with Sections 1807.2.1 through 1807.2.4.

    1807.2.1 General. Retaining walls shall be designed to ensure stability against overturning, sliding, excessive foundation pressure and water uplift.

    1807.2.2 Design lateral soil loads. Retaining walls shall be designed for the lateral soil loads set forth in Section 1610. [OSHPD 1R, 2 & 5] Retaining wall lateral soil loads determined by a geotechnical investigation report in accordance with Section 1803.5.12 and shall not be less than 80 percent of the lateral soil loads determined in accordance with Section 1610. For use with the load combina-

    18-14 2025 CALIFORNIA BUILDING CODE

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

    SOILS AND FOUNDATIONS

    tions, lateral soil loads due to gravity load surcharge shall be considered gravity loads and seismic earth pressure increases due to earthquake shall be considered as seismic loads. For structures assigned to Seismic Design Category D, E or F, the design of retaining walls supporting more than 6 feet (1829 mm) of backfill height shall incorporate the additional seismic lateral earth pressure in accordance with the geotechnical investigation where required in Section 1803.2.

    1807.2.3 Safety factor. Retaining walls shall be designed to resist the lateral action of soil to produce sliding and overturning with a minimum safety factor of 1.5 in each case. The load combinations of Section 1605 shall not apply to this requirement. Instead, design shall be based on 0.7 times nominal earthquake loads, 1.0 times other nominal loads, and investigation with one or more of the variable loads set to zero. The safety factor against lateral sliding shall be taken as the available soil resistance at the base of the retaining wall foundation divided by the net lateral force applied to the retaining wall.

    Exception: Where earthquake loads are included, the minimum safety factor for retaining wall sliding and overturning shall be 1.1.

    1807.2.4 Segmental retaining walls. Dry-cast concrete units used in the construction of segmental retaining walls shall comply with ASTM C1372.

  • CRC § 2106A.1.4 High relevance — show source text

    2106A.1.4 TMS 402, Sections 7.4.4.1 and 7.4.5.1. Replace TMS 402, Section 7.4.4.1 as follows and delete Section 7.4.5.1:

    7.4.4.1 Minimum reinforcement requirements for masonry walls. The total area of reinforcement in reinforced masonry walls shall not be less than 0.003 times the sectional area of the wall. Neither the horizontal nor the vertical reinforcement shall be less than one third of the total. Horizontal and vertical reinforcement shall be spaced at not more than 24 inches (610 mm) center to center. Where other than running bond is used in reinforced hollow unit masonry, the open-end type of unit shall be used with vertical reinforcement spaced a maximum of 16 inches (406 mm) on center.

    Exception: Reinforced hollow unit masonry used for freestanding site walls or interior nonbearing nonshear wall partitions shall have horizontal reinforcing spaced not more than 4 feet (1.2 m) on center, except for locations in Seismic Design Category F, and may be grouted only in cells containing vertical and horizontal reinforcement.

    7.4.4.1.1 The minimum reinforcing shall be No. 4, except that No. 3 bars may be used for ties and stirrups. Vertical wall reinforce- ment shall have dowels of equal size and equally matched spacing in all footings. Reinforcement shall be continuous around wall corners and through intersections. Only reinforcement which is continuous in the wall shall be considered in computing the minimum area of reinforcement. Reinforcement with splices conforming to TMS 402 shall be considered as continuous reinforcement.

    7.4.4.1.2 Horizontal reinforcing bars in bond beams shall be provided in the top of footings, at the top of wall openings, at roof and floor levels, and at the top of parapet walls. For walls 12 inches (nominal) (305 mm) or more in thickness, horizontal and vertical reinforcement shall be equally divided into two layers, except where designed as retaining walls. Where reinforcement is added above the minimum requirements, such additional reinforcement need not be so divided.

    7.4.4.1.3 In bearing walls of every type of reinforced masonry, there shall be trim reinforcement of not less than one No. 5 bar or two No. 4 bars on all sides of, and adjacent to, every opening which exceeds 16 inches (406 mm) in either direction, and such bars shall extend not less than 48 diameters, but in no case less than 24 inches (610 mm) beyond the corners of the opening. The bars required by this paragraph shall be in addition to the minimum reinforcement required elsewhere.

    7.4.4.1.4 When the reinforcement in bearing walls is designed, placed and anchored in position as for columns, the allowable stresses shall be as for columns.

    7.4.4.1.5 Joint reinforcement shall not be used as principal reinforcement in masonry.

    SECTION 2107 A —ALLOWABLE STRESS DESIGN

    2107 A .1 General. The design of masonry structures using allowable stress design shall comply with Section 2106 and the requirements of Chapters 1 through 8 of TMS 402 except as modified by Sections 2107 A .2 through 2107A.4.

  • CRC § 7.4.4.1 High relevance — show source text

    7.4.4.1 Minimum reinforcement requirements for masonry walls. The total area of reinforcement in reinforced masonry walls shall not be less than 0.003 times the sectional area of the wall. Neither the horizontal nor the vertical reinforcement shall be less than one third of the total. Horizontal and vertical reinforcement shall be spaced at not more than 24 inches (610 mm) center to center. Where other than running bond is used in reinforced hollow unit masonry, the open-end type of unit shall be used with vertical reinforcement spaced a maximum of 16 inches (406 mm) on center.

    Exception: Reinforced hollow unit masonry used for freestanding site walls or interior nonbearing nonshear wall partitions shall have horizontal reinforcing spaced not more than 4 feet (1.2 m) on center, except for locations in Seismic Design Category F, and may be grouted only in cells containing vertical and horizontal reinforcement.

    7.4.4.1.1 The minimum reinforcing shall be No. 4, except that No. 3 bars may be used for ties and stirrups. Vertical wall reinforce- ment shall have dowels of equal size and equally matched spacing in all footings. Reinforcement shall be continuous around wall corners and through intersections. Only reinforcement which is continuous in the wall shall be considered in computing the

    2025 CALIFORNIA BUILDING CODE 21-21

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

    MASONRY

    minimum area of reinforcement. Reinforcement with splices conforming to TMS 402 shall be considered as continuous reinforcement.

    7.4.4.1.2 Horizontal reinforcing bars in bond beams shall be provided in the top of footings, at the top of wall openings, at roof and floor levels, and at the top of parapet walls. For walls 12 inches (nominal) (305 mm) or more in thickness, horizontal and vertical reinforcement shall be equally divided into two layers, except where designed as retaining walls. Where reinforcement is added above the minimum requirements, such additional reinforcement need not be so divided.

    7.4.4.1.3 In bearing walls of every type of reinforced masonry, there shall be trim reinforcement of not less than one No. 5 bar or two No. 4 bars on all sides of, and adjacent to, every opening which exceeds 16 inches (406 mm) in either direction, and such bars shall extend not less than 48 diameters, but in no case less than 24 inches (610 mm) beyond the corners of the opening. The bars required by this paragraph shall be in addition to the minimum reinforcement required elsewhere.

    7.4.4.1.4 When the reinforcement in bearing walls is designed, placed and anchored in position as for columns, the allowable stresses shall be as for columns.

    7.4.4.1.5 Joint reinforcement shall not be used as principal reinforcement in masonry.

    2115.6 Allowable stress design.

    2115.6.1 TMS 402, Section 8.3.4.4 Walls. Modify TMS 402, Section 8.3.4.4 as follows by adding:

    Thickness of walls. Stresses shall be determined on the basis of the net thickness of the masonry, with consideration for reduc- tion, such as raked joints.

  • CRC § 1.1. High relevance — show source text

    DOC PS 1 Plywood grades marked:
    1.1. Structural I C-D (Exposure 1).
    1.2. C-D (Exposure 1).
    2. DOC PS 2 Plywood grades marked:
    2.1. Structural I Sheathing (Exposure 1).
    2.2. Sheathing (Exposure 1).
    3. Where a major portion of the wall is exposed above ground and a better appearance is desired, the following plywood grades marked exterior are suitable:
    3.1. Structural I A-C, Structural I B-C or Structural I C-C (Plugged) in accordance with DOC PS 1.
    3.2. A-C Group 1, B-C Group 1, C-C (Plugged) Group 1 or MDO Group 1 in accordance with DOC PS 1.
    3.3. Single Floor in accordance with DOC PS 1 or DOC PS 2.
    b. Minimum thickness15/32 inch, except crawl space sheathing shall have not less than3/8 inch for face grain across studs 16 inches on center and maximum 2-foot depth of
    unequal fill.
    c. For this fill height, thickness and grade combination, panels that are continuous over less than three spans (across less than three stud spacings) require blocking 16 inches
    above the bottom plate. Offset adjacent blocks and fasten through studs with two 16d corrosion-resistant nails at each end.|

    2025 CALIFORNIA RESIDENTIAL CODE 4-41

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

    FOUNDATIONS

    R404.2.4 Backfilling. Wood foundation walls shall not be backfilled until the basement floor and first floor have been constructed or the walls have been braced. For crawl space construction, backfill or bracing shall be installed on the interior of the walls prior to placing backfill on the exterior.

    R404.2.5 Drainage and dampproofing. Wood foundation basements shall be drained and dampproofed in accordance with Sections R405 and R406, respectively.

    R404.2.6 Fastening. Wood structural panel foundation wall sheathing shall be attached to framing in accordance with Table R602.3(1) and Section R402.1.1.

    R404.3 Wood sill plates. Wood sill plates shall be not less than 2-inch by 4-inch (51 mm by 102 mm) nominal lumber. Sill plate anchorage shall be in accordance with Sections R403.1.6 and R602.11.

    R404.4 Retaining walls. Retaining walls that are not laterally supported at the top and that retain in excess of 48 inches (1219 mm) of unbalanced fill, or retaining walls exceeding 24 inches (610 mm) in height that resist lateral loads in addition to soil, shall be designed in accordance with accepted engineering practice to ensure stability against overturning, sliding, excessive foundation pressure and water uplift. Retaining walls shall be designed for a safety factor of 1.5 against lateral sliding and overturning. This section shall not apply to foundation walls supporting buildings.

    R404.5 Precast concrete foundation walls.

  • CRC § 4-6 High relevance — show source text

    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

    Floors (On Ground) . . . . . . . . . . . . . . . . . . . . . . . . . . 5-14

    R505 Cold-Formed Steel Floor Framing . . . . . . . . . . . . . . . 5-14

    R506 Concrete Floors (On Ground) . . . . . . . . . . . . . . . . . . . 5-26

    R507 Exterior Decks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-26

    CHAPTER 6 WALL CONSTRUCTION. . . . . . . . . . . . . . . . . . . 6-3

    R601 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3

    R602 Wood Wall Framing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3

    R603 Cold-Formed Steel Wall Framing. . . . . . . . . . . . . . . . 6-53

    R604 Wood Structural Panels . . . . . . . . . . . . . . . . . . . . . . . . 6-93

    R605 Particleboard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-93

    R606 General Masonry Construction. . . . . . . . . . . . . . . . . . 6-93

  • CRC § 2.4 High relevance — show source text

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

    FOUNDATIONS

    R404.2.4 Backfilling. Wood foundation walls shall not be backfilled until the basement floor and first floor have been constructed or the walls have been braced. For crawl space construction, backfill or bracing shall be installed on the interior of the walls prior to placing backfill on the exterior.

    R404.2.5 Drainage and dampproofing. Wood foundation basements shall be drained and dampproofed in accordance with Sections R405 and R406, respectively.

    R404.2.6 Fastening. Wood structural panel foundation wall sheathing shall be attached to framing in accordance with Table R602.3(1) and Section R402.1.1.

    R404.3 Wood sill plates. Wood sill plates shall be not less than 2-inch by 4-inch (51 mm by 102 mm) nominal lumber. Sill plate anchorage shall be in accordance with Sections R403.1.6 and R602.11.

    R404.4 Retaining walls. Retaining walls that are not laterally supported at the top and that retain in excess of 48 inches (1219 mm) of unbalanced fill, or retaining walls exceeding 24 inches (610 mm) in height that resist lateral loads in addition to soil, shall be designed in accordance with accepted engineering practice to ensure stability against overturning, sliding, excessive foundation pressure and water uplift. Retaining walls shall be designed for a safety factor of 1.5 against lateral sliding and overturning. This section shall not apply to foundation walls supporting buildings.

    R404.5 Precast concrete foundation walls.

    R404.5.1 Design. Precast concrete foundation walls shall be designed in accordance with accepted engineering practice. The design and manufacture of precast concrete foundation wall panels shall comply with the materials requirements of Section R402.3 or ACI 318. The panel design drawings shall be prepared by a registered design professional where required by the statutes of the jurisdiction in which the project is to be constructed in accordance with Section R106.1.

    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:

    1. Design loading as applicable.

    2. Footing design and material.

    3. Concentrated loads and their points of application.

    4. Soil bearing capacity.

    5. Maximum allowable total uniform load.

    6. Seismic design category.

    7. 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.

  • CRC § 18-14 High relevance — show source text

    18-14 2025 CALIFORNIA BUILDING CODE

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

    SOILS AND FOUNDATIONS

    tions, lateral soil loads due to gravity load surcharge shall be considered gravity loads and seismic earth pressure increases due to earthquake shall be considered as seismic loads. For structures assigned to Seismic Design Category D, E or F, the design of retaining walls supporting more than 6 feet (1829 mm) of backfill height shall incorporate the additional seismic lateral earth pressure in accordance with the geotechnical investigation where required in Section 1803.2.

    1807.2.3 Safety factor. Retaining walls shall be designed to resist the lateral action of soil to produce sliding and overturning with a minimum safety factor of 1.5 in each case. The load combinations of Section 1605 shall not apply to this requirement. Instead, design shall be based on 0.7 times nominal earthquake loads, 1.0 times other nominal loads, and investigation with one or more of the variable loads set to zero. The safety factor against lateral sliding shall be taken as the available soil resistance at the base of the retaining wall foundation divided by the net lateral force applied to the retaining wall.

    Exception: Where earthquake loads are included, the minimum safety factor for retaining wall sliding and overturning shall be 1.1.

    1807.2.4 Segmental retaining walls. Dry-cast concrete units used in the construction of segmental retaining walls shall comply with ASTM C1372.

    1807.2.5 Guards. Guards shall be provided at retaining walls in accordance with Sections 1807.2.5.1 through 1807.2.5.3.

    Exception: Guards are not required at retaining walls not accessible to the public.

    1807.2.5.1 Where required. At retaining walls located within 36 inches (914mm) of walking surfaces, a guard shall be required between the walking surface and the open side of the retaining wall where the walking surface is located more than 30 inches (762 mm) measured vertically to the surface or grade below at any point within 36 inches (914mm) horizontally to the edge of the open side. Guards shall comply with Section 1607.9.

    1807.2.5.2 Height. Required guards at retaining walls shall comply with the height requirements of Section 1015.3.

    1807.2.5.3 Opening limitations. Required guards shall comply with the opening limitations of Section 1015.4.

    1807.3 Embedded posts and poles. Designs to resist both axial and lateral loads employing posts or poles as columns embedded in earth or in concrete footings in earth shall be in accordance with Sections 1807.3.1 through 1807.3.3 or ASABE EP 486.3.

    1807.3.1 Limitations. The design procedures outlined in this section are subject to the following limitations:

    1. The frictional resistance for structural walls and slabs on silts and clays shall be limited to one-half of the normal force imposed on the soil by the weight of the footing or slab.
    2. Posts embedded in earth shall not be used to provide lateral support for structural or nonstructural materials such as plaster, masonry or concrete unless bracing is provided that develops the limited deflection required.

    Wood poles shall be treated in accordance with AWPA U1 for sawn timber posts (Commodity Specification A, Use Category 4B) and for round timber posts (Commodity Specification B, Use Category 4B).

  • CRC § 25.4 High relevance — show source text

    ML-CL and**
    inorganic CL 60| |8|4|NR|NR|NR| |8|5|NR|6 @ 39|6 @ 48| |8|6|5 @ 39|6 @ 48|6 @ 35| |8|7|6 @ 48|6 @ 34|6 @ 25| |8|8|6 @ 39|6 @ 25|6 @ 18| |9|4|NR|NR|NR| |9|5|NR|5 @ 37|6 @ 48| |9|6|5 @ 36|6 @ 44|6 @ 32| |9|7|6 @ 47|6 @ 30|6 @ 22| |9|8|6 @ 34|6 @ 22|6 @ 16| |9|9|6 @ 27|6 @ 17|DR| |10|4|NR|NR|NR| |10|5|NR|5 @ 35|6 @ 48| |10|6|6 @ 48|6 @ 41|6 @ 30| |10|7|6 @ 43|6 @ 28|6 @ 20| |10|8|6 @ 31|6 @ 20|DR| |10|9|6 @ 24|6 @ 15|DR| |10|10|6 @ 19|DR|DR| |For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot per foot = 0.1571 kPa2/m, 1 pound per square inch = 6.895 kPa.
    NR = Not Required.
    DR = Design Required.
    a. Soil classes are in accordance with the Unified Soil Classification System. Refer to Table R401.4.1(2).
    b. Table values are based on reinforcing bars with a minimum yield strength of 60,000 psi concrete with a minimum specified compressive strength of 2,500 psi and vertical
    reinforcement being located at the centerline of the wall. See Section R404.1.3.3.7.2.
    c. Vertical reinforcement with a yield strength of less than 60,000 psi and bars of a different size than specified in the table are permitted in accordance with Section
    R404.1.3.3.7.6 and Table R404.1.3.2(9).
    d. Deflection criterion is_L_/240, where_L_ is the height of the basement wall in inches.
    e. Interpolation is not permitted.
    f. Where walls will retain 4 feet or more of unbalanced backfill, they shall be laterally supported at the top and bottom before backfilling.
    g. NR indicates vertical wall reinforcement is not required, except for 6-inch-nominal walls formed with stay-in-place forming systems in which case vertical reinforcement shall
    be No. 4@48 inches on center.
    h. See Section R404.1.3.2 for minimum reinforcement required for basement walls supporting above-grade concrete walls.
    i. See Table R608.3 for tolerance from nominal thickness permitted for flat walls.
    j. DR means design is required in accordance with the applicable building code, or in the absence of a code, in accordance with ACI 318.
    k.

  • CRC § 7.1.1 Medium relevance — show source text

    For buildings with a mean roof height of less than 35 feet, tabulated lengths are permitted to be reduced by multiplying by the appropriate factor,_R_1, from Table R608.7.1.1(4).
    The reduced length shall be not less than the “minimum” value shown in the table.
    d. Tabulated lengths for “one story or top story of two story” are based on a floor-to-ceiling height of 10 feet. Tabulated lengths for “first story of two story” are based on floor-
    to-ceiling heights of 10 feet each for the first and second story. For floor-to-ceiling heights less than assumed, use the lengths in this table or Table R608.7.1.1(2) or (3), or
    multiply the value in the table by the reduction factor,_R_2, from Table R608.7.1.1(5).
    e. Tabulated lengths are based on the default design shear strength of 840 pounds per linear foot of solid wall segment. The tabulated lengths are permitted to be reduced by
    multiplying by the applicable reduction factor for design strength,_R_3, from Table R608.7.1.1(6).
    f. The reduction factors,_R_1, R_2 and_R_3, in Tables R608.7.1.1(4), R608.7.1.1(5), and R608.7.1.1(6), respectively, are permitted to be compounded, subject to the limitations of Note
    b. However, the minimum number and minimum length of solid wall segments in each wall line shall comply with Sections R608.7.1 and R608.7.2.1, respectively.
    g. For intermediate values of sidewall length, endwall length, roof slope and_basic wind speed    , use the next higher value, or determine by interpolation.|For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 mile per hour = 0.447 m/s, 1 pound-force per linear foot = 0.146 kN/m, 1 pound per square foot = 47.88 Pa.
    a. Tabulated lengths were derived by calculating design wind pressures in accordance with Figure 28.4-1 of ASCE 7 for a building with a mean roof height of 35 feet, topographic
    factor,Kzt, equal to 1.0, and Risk Category II. For wind perpendicular to the ridge, the effects of a 2-foot overhang on each endwall are included. The design pressures were
    used to calculate forces to be resisted by solid wall segments in each. The forces to be resisted by each wall line were then divided by the default design strength of 840
    pounds per linear foot of length to determine the unreduced length,UR, of solid wall length required in each endwall. The actual mean roof height of the building shall not
    exceed the least horizontal dimension of the building.
    b. Tabulated lengths in the “minimum” column are based on the requirement of Section 28.4.4 of ASCE 7 that the main windforce-resisting system be designed for a minimum
    pressure of 16 psf multiplied by the wall area of the building and 8 psf multiplied by the roof area of the building projected onto a vertical plane normal to the assumed wind
    direction. Tabulated lengths in shaded cells are less than the “minimum” value. Where the minimum controls, it is permitted to be reduced in accordance with Notes c, d and
    e.

  • CRC § 304.8 Medium relevance — show source text

    4 mm, 1 foot = 304.8 mm, 1 mph = 0.447 m/s.|For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 mph = 0.447 m/s.|For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 mph = 0.447 m/s.|For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 mph = 0.447 m/s.|For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 mph = 0.447 m/s.|

    SECTION R404—FOUNDATION AND RETAINING WALLS

    R404.1 Concrete and masonry foundation walls. Concrete foundation walls shall be selected and constructed in accordance with the provisions of Section R404.1.3. Masonry foundation walls shall be selected and constructed in accordance with the provisions of Section R404.1.2.

    R404.1.1 Design required. Concrete or masonry foundation walls shall be designed in accordance with accepted engineering practice where either of the following conditions exists:

    1. Walls are subject to hydrostatic pressure from ground water.
    2. Walls supporting more than 48 inches (1219 mm) of unbalanced backfill that do not have permanent lateral support at the top or bottom.

    R404.1.2 Design of masonry foundation walls. Masonry foundation walls shall be designed and constructed in accordance with the provisions of this section or in accordance with the provisions of TMS 402. Where TMS 402 or the provisions of this section are used to design masonry foundation walls, project drawings, typical details and specifications are not required to bear the seal of the architect or engineer responsible for design, unless otherwise required by the state law of the jurisdiction having authority.

    R404.1.2.1 Masonry foundation walls. Concrete masonry and clay masonry foundation walls shall be constructed as set forth in Table R404.1.2.1(1), R404.1.2.1(2), R404.1.2.1(3) or R404.1.2.1(4) and shall comply with applicable provisions of Section R606. In buildings assigned to Seismic Design Categories D 0, D 1 and D 2, concrete masonry and clay masonry foundation walls shall also comply with Section R404.1.4.1. Rubble stone masonry foundation walls shall be constructed in accordance with Sections R404.1.8 and R606.4.2. Rubble stone masonry walls shall not be used in Seismic Design Categories D 0, D 1 and D 2, or in townhouses in Seismic Design Category C.

    4-24 2025 CALIFORNIA RESIDENTIAL CODE

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

    FOUNDATIONS

    TABLE R404.1.2.1(1)—PLAIN MASONRY FOUNDATION WALLSf Col2 Col3 Col4 Col5
    ** MAXIMUM**
    UNSUPPORTED
    WALL HEIGHT
    (feet)    		 ** MAXIMUM**
    UNBALANCED
    BACKFILL HEIGHTc
    (feet)    		 ** PLAIN MASONRYa MINIMUM NOMINAL WALL THICKNESS (inches)** ** PLAIN

Frequently asked questions

Do I always need an engineer for a yard wall?

If the wall meets the triggers in § R404.4 — i.e., not laterally supported at top and retaining > 48 in of unbalanced fill, or is > 24 in and resists lateral loads beyond soil — an engineered design is required. For smaller, purely decorative walls that do not meet these thresholds, engineered design is not mandated by § R404.4, but local jurisdictions may have other requirements.

What safety factor does the code require?

The CRC requires a minimum safety factor of 1.5 against overturning and sliding for retaining walls covered by § R404.4.

Are foundation walls treated the same as freestanding retaining walls?

No. Foundation walls that support buildings are governed by the foundation provisions (see § R404.1.1 and § R404.1.3). § R404.4 explicitly excludes foundation walls supporting buildings.

Do I need to provide drainage behind the wall?

Yes—where a wall retains earth and encloses habitable or usable spaces below grade, drainage around the foundation is required under § R405; even for freestanding retaining walls good practice and many jurisdictions require drain tiles/weep systems to control hydrostatic pressure.

If my wall is 42 inches high, do I need engineering?

If the wall is 42 in (< 48 in) of unbalanced fill and it does not resist lateral loads other than soil, § R404.4 would not automatically require engineering. However, if the wall resists additional lateral loads (surcharge) or other local rules apply, engineering may still be required. Always confirm with the local building official.

More in California Residential Code

Ask about the CRC

Get cited, plain-English answers on the California Residential Code for your project — any code section, any scenario.

Start Free Trial

Related in the CRC

When must foundation or basement walls be designed by a registered design professional?

What are the rules for wood foundation walls and sill plate anchorage?

How are concrete and masonry foundation walls selected and sized (thickness, reinforcement)?

Foundation and retaining wall requirements

California Residential Code