CBC · California Building Code

Minimum reinforcement: area, spacing, spacing limits and termination requirements

For homeowners: the California Building Code requires a small but definite amount of steel in masonry walls — at least 0.3% of the wall cross‑section, spaced no more than 24 inches (16 inches for certain hollow blocks), with special, larger bars required around openings. The CBC text and amendments (notably § 7.4.4.1 and § 2106A.1.4) spell out the exact minimums and where the bars must be continuous and extended.

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Last reviewed: July 5, 2026

What the code requires — 2-4 sentences

The California Building Code (amending TMS 402) sets a uniform minimum distributed reinforcement for reinforced masonry walls: the total reinforcement area shall be at least 0.003 times the wall sectional area, with neither horizontal nor vertical less than one‑third of that total; maximum spacing is generally 24 inches on center (special limits apply for open‑end hollow units). These requirements appear in § 7.4.4.1 as adopted by the CBC and the CBC amendment § 2106A.1.4; the trim/edge reinforcement for openings is specified in § 7.4.4.1.3.

Requirements in detail

How the minimum area is prescribed

Minimum total reinforcement (sum of horizontal + vertical) = 0.003 × gross sectional area of the wall. Neither horizontal nor vertical may be less than 1/3 of that total. See § 7.4.4.1.

Maximum spacing limits

Horizontal and vertical reinforcement spacing shall be no more than 24 inches (610 mm) center to center in general. See § 7.4.4.1.
Where reinforced hollow‑unit masonry is laid in a bond other than running bond, the open‑end type of unit must be used and vertical reinforcement spacing is limited to a maximum of 16 inches (406 mm) on center. See § 7.4.4.1.
Exception: Freestanding site walls or interior nonbearing nonshear partitions (reinforced hollow unit masonry) may have horizontal reinforcing spaced up to 4 feet (1.2 m) on center (not permitted in Seismic Design Category F), and may be grouted only in cells containing vertical and horizontal reinforcement. See § 7.4.4.1.

Minimum bar size, continuity, and location rules

Minimum principal reinforcing bar size is No. 4; No. 3 bars are permitted for ties and stirrups. Vertical wall reinforcement shall have dowels of equal size and spacing in footings. Reinforcement shall be continuous around corners and through intersections; only reinforcement that is continuous in the wall is counted toward the minimum area. Splices conforming to TMS 402 are permitted and are considered continuous. See § 7.4.4.1.1.
Horizontal reinforcing bars in bond beams are required at the top of footings, at the tops of openings, at roof and floor levels, and at the top of parapet walls. For walls nominally 12 inches or thicker, vertical and horizontal reinforcement shall be equally divided into two layers (except for retaining walls). See § 7.4.4.1.2.
Joint reinforcement is explicitly prohibited from being used as principal reinforcement. See § 7.4.4.1.5.

Trim (edge) reinforcement and termination at openings

Bearing walls must have trim reinforcement around every opening larger than 16 inches in either direction: at least one No. 5 bar or two No. 4 bars on all sides and adjacent to the opening. Those bars must extend not less than 48 bar diameters, but in no case less than 24 inches (610 mm) beyond the corners of the opening. Trim bars are required in addition to the minimum distributed reinforcement. See § 7.4.4.1.3.

CBC adoption / amendment note

The CBC replaces TMS 402, Section 7.4.4.1 with the language above through the amendment contained in § 2106A.1.4; the CBC text containing these replacement provisions is the controlling language in California. See § 2106A.1.4.

Quick decision table

Decision item	Value / limit	Code Reference
Minimum total reinforcement area	0.003 × wall sectional area	§ 7.4.4.1
Minimum in each direction (horizontal or vertical)	≥ 1/3 of total minimum area	§ 7.4.4.1
Maximum spacing (typical)	24 in (610 mm) o.c.	§ 7.4.4.1
Vertical spacing for non‑running bond hollow units	16 in (406 mm) o.c.	§ 7.4.4.1
Exception — freestanding/interior nonbearing partitions	Horizontal spacing up to 4 ft; grout only cells with reinforcement (not allowed in SDC F)	§ 7.4.4.1 (Exception)
Minimum principal bar size	No. 4 (No. 3 permitted for ties/stirrups)	§ 7.4.4.1.1
Trim reinforcement for openings > 16 in	1 × No. 5 or 2 × No. 4; extend ≥ 48 diameters but ≥ 24 in beyond corners	§ 7.4.4.1.3
Bond beam horizontal locations	Top of footing, top of openings, roof/floor levels, top of parapet	§ 7.4.4.1.2

Exceptions & special cases

Freestanding site walls and interior nonbearing nonshear partitions of reinforced hollow unit masonry: horizontal reinforcement may be spaced up to 4 ft o.c., except in Seismic Design Category F; such walls may be grouted only in the cells that contain reinforcement. See § 7.4.4.1 (Exception).
Where other standards or tables (e.g., other CBC chapters, design tables for foundation walls) prescribe different minimums for specific wall types, those provisions may control for that application — always check the applicable chapter/table. The CBC’s amendment language in § 2106A.1.4 is the controlling text for the TMS 402 minimums in California.
Trim reinforcement length is governed by bar diameter multiples (48× db) with an absolute minimum of 24 in; this means that for large bars the 48 diameters control, but for smaller bars 24 in may control. See § 7.4.4.1.3.

Common mistakes

Counting reinforcement that is not continuous (e.g., short lap pieces not meeting splice requirements or isolated joint reinforcement) toward the minimum area — the code counts only continuous reinforcement or splices conforming to TMS 402. See § 7.4.4.1.1.
Using joint reinforcement (ladder-type) as the principal distributed reinforcement — expressly prohibited. See § 7.4.4.1.5.
Forgetting the “neither direction less than one‑third” rule: meeting the total area but concentrating nearly all reinforcement in one direction violates § 7.4.4.1.
Failing to provide the required trim reinforcement or to extend the trim bars the required 48 diameters (or 24 in minimum) beyond the opening corners in bearing walls. See § 7.4.4.1.3.
Forgetting the reduced spacing requirement (16 in o.c.) when hollow units are not running bond (and open‑end units are required). See § 7.4.4.1.

Worked example — concrete scenario with numbers

Scenario: an 8‑inch nominal reinforced masonry bearing wall; evaluate minimum required distributed reinforcement per foot of wall length.

Compute sectional (gross cross‑section) area per linear foot:
- Wall thickness = 8 in; 1 ft of wall length = 12 in.
- Cross‑sectional area (per foot) = 8 in × 12 in = 96 in².
Minimum total reinforcement area:
- 0.003 × 96 in² = 0.288 in² total reinforcement per foot of wall. (This is the CBC/TMS requirement from § 7.4.4.1.)
Minimum in each direction:
- Neither direction can be less than one‑third of total → 0.288 / 3 = 0.096 in² minimum in horizontal and 0.096 in² minimum in vertical. See § 7.4.4.1.
Spacing check:
- Maximum spacing is 24 in o.c. (typical). If you choose #4 bars at 24 in o.c., there is one #4 bar every 2 ft of wall or 0.5 bar per foot.
- To determine whether #4 @ 24 in meets the 0.096 in² requirement you must know the cross‑sectional area of a #4 bar (bar areas are standard steel properties, not printed in the retrieved CBC text). For example, a No. 4 bar has a standard area of about 0.20 in² (standard bar areas come from structural handbooks / ASTM tables, not from the CBC text). Using that common reference, #4 @ 24 in yields 0.20 × 0.5 = 0.10 in² per foot — which is slightly greater than the 0.096 in² required per direction, and therefore would meet the minimum in each direction and the spacing limit. (Because bar areas are not part of the retrieved CBC text, verify bar area from manufacturer/ASTM tables in final design.) See § 7.4.4.1 and § 7.4.4.1.1.

Notes:

The example uses standard bar area values (for illustration) which are not contained in the CBC extracts; the code requires only how to compute minimum area and spacing — selecting bar sizes/spacing to achieve that area is the designer’s responsibility and must reference standard bar area tables.

Related provisions

§ 7.4.4.1.1 — Minimum bar size; continuity, dowels in footings, splices counted as continuous.
§ 7.4.4.1.2 — Locations where horizontal reinforcing (bond beams) must be provided and layer distribution for thick walls.
§ 7.4.4.1.3 — Trim reinforcement requirements around openings (detail and extension lengths).
§ 7.4.4.1.5 — Joint reinforcement shall not be used as principal reinforcement.
§ 2106A.1.4 — CBC amendment replacing TMS 402 § 7.4.4.1 (adopted language controlling these minimums in California).
§ 2106A.1.3 / § 2115.5.2 — Related CBC amendments addressing termination of horizontal reinforcement embedded in grout for particular shear / geometry conditions (see these sections when termination/detailing is at issue).

Code references

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

CBC § 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.
CBC § 12.7 High relevance — show source text
(12.7 mm) in diameter. (b) Vertical spacing of lateral ties, over the full height of the column, shall not exceed 8 longitudinal bar diameters, 24 lateral tie bar diameters, 8 inches (203 mm), or one-half the least cross-sectional dimension of the member. (d) Lateral ties shall be embedded in grout. (e) Lateral ties shall be located vertically not more than one-half lateral tie spacing above the top of the footing or slab in any story, and shall be spaced not more than one-half a lateral tie spacing nor 2 inches (51 mm) below the lowest horizontal reinforcement in beam, girder, slab, or drop panel above. The top tie shall be within 2 inches (51 mm) of the top of the column.

2115.5.2 TMS 402, Section 7.3.2.5 (i). Replace first sentence of TMS 402, Section 7.3.2.5 (i) by the following: (i) When the ratio of V/F vm A mv for masonry designed in accordance with Chapter 8 or when the ratio V u /ΦV nm for masonry designed in accordance with Chapter 9 exceeds 0.15, or the h w /l w exceeds 0.5, the termination of horizontal reinforcement embedded in grout shall meet one of the following:

2115.5.3 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

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.
CBC § 2106A.1.2 High relevance — show source text
( 9.5 mm ) in diameter. (b) Vertical spacing of lateral ties, over the full height of the column, shall not exceed 8 longitudinal bar diameters, 24 lateral tie bar diameters, 8 inches (203 mm), or one-half the least cross-sectional dimension of the member. (d) Lateral ties shall be embedded in grout. (e) Lateral ties shall be located vertically not more than one-half lateral tie spacing above the top of the footing or slab in any story, and shall be spaced not more than one-half a lateral tie spacing nor 2 inches (51 mm) below the lowest horizontal reinforcement in beam, girder, slab, or drop panel above. The top tie shall be within 2 inches (51 mm) of the top of the column.

2106A.1.2 TMS 402, Chapter 5. Add TMS 402, Section 5.7 as follows:

5.7 – Lateral Support of Members

5.7.1 – Lateral support of masonry may be provided by cross walls, columns, pilasters, counterforts or buttresses where spanning horizontally, or by floors, beams, girts or roofs where spanning vertically. Where walls are supported laterally by vertical elements, the stiffness of each vertical element shall exceed that of the tributary area of the wall.

21A-8 2025 CALIFORNIA BUILDING CODE

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

MASONRY

2106A.1.3 TMS 402, Section 7.3.2.5 (i). Replace first sentence of TMS 402, Section 7.3.2.5 (i) by the following: (i) When the ratio of V/F vm A mv for masonry designed in accordance with Chapter 8 or when the ratio V u /ΦV nm for masonry design in accordance with Chapter 9 exceeds 0.15, or the h w /l w exceeds 0.5, the termination of horizontal reinforcement embedded in grout shall meet one of the following:

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.
CBC § 1.0 Medium relevance — show source text
Table is based on ASCE 7 components and cladding wind pressures for an enclosed building using a mean roof height of 35 feet, interior wall area 4, an effective wind area of
10 square feet, topographic factor,Kzt, equal to 1.0, and Risk Category II.
b. Table is based on concrete with a minimum specified compressive strength of 2,500 psi.
c. See Section R608.6.5 for location of reinforcement in wall.
d. Deflection criterion is_L_/240, where_L_ is the unsupported height of the wall in inches.
e. Interpolation is not permitted.
f. Where No. 4 reinforcing bars at a spacing of 48 inches are specified in the table as indicated by shaded cells, use of bars with a minimum yield strength of 40,000 psi or 60,000
psi is permitted.
g. Other than for No. 4 bars spaced at 48 inches on center, table values are based on reinforcing bars with a minimum yield strength of 60,000 psi. 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 such as, 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
or bars of a different size than specified in the table are permitted in accordance with Section R608.5.4.7 and Table R608.5.4(2).
h. See Table R608.3 for minimum core dimensions and maximum spacing of horizontal and vertical cores.
i. “Top” means gravity load from roof or floor construction bears on top of wall. “Side” means gravity load from floor construction is transferred to wall from a wood ledger or
cold-formed steel track bolted to side of wall. For nonload-bearing walls and where floor framing members span parallel to the wall, the “Top” bearing condition is permitted
to be used.|For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 mile per hour = 0.447 m/s, 1 pound per square inch = 6.895 kPa, 1 square foot = 0.0929 m2.
a. Table is based on ASCE 7 components and cladding wind pressures for an enclosed building using a mean roof height of 35 feet, interior wall area 4, an effective wind area of
10 square feet, topographic factor,Kzt, equal to 1.0, and Risk Category II.
b. Table is based on concrete with a minimum specified compressive strength of 2,500 psi.
c. See Section R608.6.5 for location of reinforcement in wall.
d. Deflection criterion is_L_/240, where_L_ is the unsupported height of the wall in inches.
e. Interpolation is not permitted.
f. Where No. 4 reinforcing bars at a spacing of 48 inches are specified in the table as indicated by shaded cells, use of bars with a minimum yield strength of 40,000 psi or 60,000
psi is permitted.
g. Other than for No. 4 bars spaced at 48 inches on center, table values are based on reinforcing bars with a minimum yield strength of 60,000 psi. Maximum spacings shown are
the values calculated for the specified bar size.

CBC § 1610.1 Medium relevance — show source text

Where unbalanced backfill height exceeds 8 feet and design lateral soil loads from Table 1610.1 are used, the requirements for 30 and 45 psf per foot of depth are not applica-
ble. See Section 1610.|

TABLE 1807.1.6.3(3)—10-INCH MASONRY FOUNDATION WALLS WITH REINFORCEMENT WHERE d ≥ 6.75 INCHESa, b, c	Col2	Col3	Col4	Col5
MAXIMUM WALL HEIGHT (feet-inches)	MAXIMUM UNBALANCED BACKFILL HEIGHTd (feet-inches)	MINIMUM VERTICAL REINFORCEMENT-BAR SIZE AND SPACING (inches)	MINIMUM VERTICAL REINFORCEMENT-BAR SIZE AND SPACING (inches)	MINIMUM VERTICAL REINFORCEMENT-BAR SIZE AND SPACING (inches)
MAXIMUM WALL HEIGHT (feet-inches)	MAXIMUM UNBALANCED BACKFILL HEIGHTd (feet-inches)	Design lateral soil loada (psf per foot of depth)	Design lateral soil loada (psf per foot of depth)	Design lateral soil loada (psf per foot of depth)
MAXIMUM WALL HEIGHT (feet-inches)	MAXIMUM UNBALANCED BACKFILL HEIGHTd (feet-inches)	30e	45e	60
7-4	4-0 (or less) 5-0 6-0 7-4	#4 at 56 #4 at 56 #4 at 56 #4 at 56	#4 at 56 #4 at 56 #4 at 56 #5 at 56	#4 at 56 #4 at 56 #5 at 56 #6 at 56
8-0	4-0 (or less) 5-0 6-0 7-0 8-0	#4 at 56 #4 at 56 #4 at 56 #4 at 56 #5 at 56	#4 at 56 #4 at 56 #4 at 56 #5 at 56 #6 at 56	#4 at 56 #4 at 56 #5 at 56 #6 at 56 #7 at 56
8-8	4-0 (or less) 5-0 6-0 7-0 8-8e	#4 at 56 #4 at 56 #4 at 56 #4 at 56 #5 at 56	#4 at 56 #4 at 56 #4 at 56 #5 at 56 #7 at 56	#4 at 56 #4 at 56 #5 at 56 #6 at 56 #8 at 56
9-4	4-0 (or less) 5-0 6-0 7-0 8-0 9-4e	#4 at 56 #4 at 56 #4 at 56 #4 at 56 #5 at 56 #6 at 56	#4 at 56 #4 at

CBC § 25.4 Medium 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 @ 48|5 @ 43| |8|5|4 @ 48|5 @ 48|5 @ 37| |8|6|5 @ 48|6 @ 45|6 @ 32| |8|7|6 @ 48|DR|DR| |8|8|6 @ 36|DR|DR| |9|4|4 @ 48|4 @ 48|4 @ 41| |9|5|4 @ 48|5 @ 48|6 @ 48| |9|6|5 @ 45|6 @ 41|DR| |9|7|6 @ 43|DR|DR| |9|> 8|DR|DR|DR| |10|4|4 @ 48|4 @ 48|4 @ 39| |10|5|4 @ 44|5 @ 44|6 @ 46| |10|6|5 @ 42|6 @ 38|DR| |10|7|6 @ 40|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
reinforcement 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 Sections 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 screen-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.

CBC § 12.3 Medium relevance — show source text

R606.12.3 Seismic Design Category D 0 or D 1 . Structures in Seismic Design Category D 0 or D 1 shall comply with the requirements of Seismic Design Category C and the additional requirements of this section. AAC masonry shall not be used for the design of masonry elements that are part of the lateral force-resisting system.

R606.12.3.1 Design requirements. Masonry elements other than those covered by Section R606.12.2.2.2 shall be designed in accordance with the requirements of Chapters 1 through 7 and Sections 8.1 and 8.3 of TMS 402 and shall meet the minimum reinforcement requirements contained in Sections R606.12.3.2 and R606.12.3.2.1. Otherwise, masonry shall be designed in accordance with TMS 403.

Exception: Masonry walls limited to one story in height and 9 feet (2743 mm) between lateral supports need not be designed provided they comply with the minimum reinforcement requirements of Sections R606.12.3.2 and R606.12.3.2.1.

R606.12.3.2 Minimum reinforcement requirements for masonry walls. Masonry walls other than those covered by Section R606.12.2.2.3 shall be reinforced in both the vertical and horizontal direction. The sum of the cross-sectional area of horizontal and vertical reinforcement shall be not less than 0.002 times the gross cross-sectional area of the wall, and the minimum crosssectional area in each direction shall be not less than 0.0007 times the gross cross-sectional area of the wall. Reinforcement shall be uniformly distributed. Table R606.12.3.2 shows the minimum reinforcing bar sizes required for varying thicknesses of masonry walls. The maximum spacing of reinforcement shall be 48 inches (1219 mm) provided that the walls are solid grouted and constructed of hollow open-end units, hollow units laid with full head joints or two wythes of solid units. The maximum spacing of reinforcement shall be 24 inches (610 mm) for all other masonry.

TABLE R606.12.3.2—MINIMUM DISTRIBUTED WALL REINFORCEMENT FOR BUILDINGS ASSIGNED TO SEISMIC DESIGN CATEGORY D or D 0 1	Col2	Col3	Col4
NOMINAL WALL THICKNESS (inches)	MINIMUM SUM OF THE VERTICAL AND HORIZONTAL REINFORCEMENT AREASa (square inches per foot)	MINIMUM REINFORCEMENT AS DISTRIBUTED IN BOTH HORIZONTAL AND VERTICAL DIRECTIONSb (square inches per foot)	MINUMUM BAR SIZE FOR REINFORCEMENT SPACED AT 48 INCHES
6	0.135	0.047	#4
8	0.183	0.064	#5
10	0.231	0.081	#6
12	0.279	0.098	#6
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 square inch per foot = 2064 mm2/m. a.

CBC § 1807.1.6.2 Medium relevance — show source text

1807.1.6.2 Concrete foundation walls. Concrete foundation walls shall comply with the following:

The thickness shall comply with the requirements of Table 1807.1.6.2.
The size and spacing of vertical reinforcement shown in Table 1807.1.6.2 are based on the use of reinforcement with a minimum yield strength of 60,000 pounds per square inch (psi) (414 MPa). Vertical reinforcement with a minimum yield strength of 40,000 psi (276 MPa) or 50,000 psi (345 MPa) shall be permitted, provided that the same size bar is used and the spacing shown in the table is reduced by multiplying the spacing by 0.67 or 0.83, respectively.
Vertical reinforcement, where required, shall be placed nearest the inside face of the wall a distance, d, from the outside face (soil face) of the wall. The distance, d, is equal to the wall thickness, t, minus 1.25 inches (32 mm) plus one-half the bar diameter, d b , [ d = t – (1.25 + d b /2)]. The reinforcement shall be placed within a tolerance of ± [3] / 8 inch (9.5 mm) where d is less than or equal to 8 inches (203 mm) or ± [1] / 2 inch (12.7 mm) where d is greater than 8 inches (203 mm).
In lieu of the reinforcement shown in Table 1807.1.6.2, smaller reinforcing bar sizes with closer spacings that provide an equivalent cross-sectional area of reinforcement per unit length shall be permitted.
Concrete cover for reinforcement measured from the inside face of the wall shall be not less than [3] / 4 inch (19.1 mm). Concrete cover for reinforcement measured from the outside face of the wall shall be not less than 1 [1] / 2 inches (38 mm) for No. 5 bars and smaller, and not less than 2 inches (51 mm) for larger bars.
Concrete shall have a specified compressive strength, f′ c , of not less than 2,500 psi (17.2 MPa).
The unfactored axial load per linear foot of wall shall not exceed 1.2 tf ′ c where t is the specified wall thickness in inches.

TABLE 1807.1.6.2—CONCRETE FOUNDATION WALLSb, c	Col2	Col3	Col4	Col5	Col6	Col7	Col8	Col9	Col10	Col11
MAXIMUM WALL HEIGHT (feet)	MAXIMUM UNBALANCED BACKFILL HEIGHTe (feet)	MINIMUM VERTICAL REINFORCEMENT-BAR SIZE AND SPACING (inches)	MINIMUM VERTICAL REINFORCEMENT-BAR SIZE AND SPACING (inches)	MINIMUM VERTICAL REINFORCEMENT-BAR SIZE AND SPACING (inches)	MINIMUM VERTICAL REINFORCEMENT-BAR SIZE AND SPACING (inches)	MINIMUM VERTICAL REINFORCEMENT-BAR SIZE AND SPACING (inches)	**MINIMUM VERTICAL REINFORCEMENT-BAR SIZE AND

CBC § 1810.3.9.4.2.1 Medium relevance — show source text
Transverse reinforcement shall consist of closed ties or spirals not smaller than No. 3 bars for elements with a least dimension up to 20 inches (508 mm), and No. 4 bars for larger elements. Throughout the remainder of the reinforced length outside the regions with transverse confinement reinforcement, as specified in Section 1810.3.9.4.2.1 or 1810.3.9.4.2.2, the spacing of transverse reinforcement shall not exceed the least of the following:
1. 12 longitudinal bar diameters.
2. One-half the least dimension of the element.
3. 12 inches (305 mm).
Exceptions:
1. The requirements of this section shall not apply to concrete cast in structural steel pipes or tubes.
2. A spiral-welded metal casing of a thickness not less than manufacturer’s standard No. 14 gage (0.068 inch) is permitted to provide concrete confinement in lieu of the closed ties or spirals. Where used as such, the metal casing shall be protected against possible deleterious action due to soil constituents, changing water levels or other factors indicated by boring records of site conditions.
1810.3.9.4.2.1 Site Classes A through DE. For Site Class A, B, BC, C, CD, D or DE sites, transverse confinement reinforcement shall be provided in the element in accordance with Sections 18.7.5.2, 18.7.5.3 and 18.7.5.4 of ACI 318 within three times the least element dimension of the bottom of the pile cap. A transverse spiral reinforcement ratio of not less than one-half of that required in Table 18.10.6.4(g) of ACI 318 shall be permitted.

1810.3.9.4.2.2 Site Classes E and F. For Site Class E or F sites, transverse confinement reinforcement shall be provided in the element in accordance with Sections 18.7.5.2, 18.7.5.3 and 18.7.5.4 of ACI 318 within seven times the least element dimension of the pile cap and within seven times the least element dimension of the interfaces of strata that are hard or stiff and strata that are liquefiable or are composed of soft- to medium-stiff clay.

1810.3.9.5 Belled drilled shafts. Where drilled shafts are belled at the bottom, the edge thickness of the bell shall be not less than that required for the edge of footings. Where the sides of the bell slope at an angle less than 60 degrees (1 rad) from the horizontal, the effects of vertical shear shall be considered.

1810.3.9.6 Socketed drilled shafts. Socketed drilled shafts shall have a permanent pipe or tube casing that extends down to bedrock and an uncased socket drilled into the bedrock, both filled with concrete. Socketed drilled shafts shall have reinforcement or a structural steel core for the length as indicated by an approved method of analysis.

The depth of the rock socket shall be sufficient to develop the full load-bearing capacity of the element with a minimum safety factor of two, but the depth shall be not less than the outside diameter of the pipe or tube casing. The design of the rock socket is permitted to be predicated on the sum of the allowable load-bearing pressure on the bottom of the socket plus bond along the sides of the socket.

Where a structural steel core is used, the gross cross-sectional area of the core shall not exceed 25 percent of the gross area of the drilled shaft.
California Building Code Medium relevance — show source text
|100 psf|1 hr
23 min|||7|1, 2|11/3| |F/C-4-RC-9|4″|4″ deep (4370 psi);1/4″ reinforcement bars
at 6″ pitch with3/4″ cover;1/4″ main rein-
forcement bars at 4″ pitch perpendicular
with1/2″ cover; 13′1″ span restrained.|150 psf|2 hrs|||7|1, 3|2| |F/C-4-RC-10|4″|4″ thick (5140 psi) deck;1/4″ reinforce-
ment bars at 71/2″ pitch with7/8″ cover;3/8″
main reinforcement bars at 33/4″ pitch
perpendicular with1/2″ cover; 13′1″ span
restrained.|140 psf|1 hr
16 min|||7|1, 5|11/4| |F/C-4-RC-11|4″|4″ thick (4000 psi) concrete deck;
3″ × 11/2″ × 4 lbs R.S.J.; 2′6″ C.R.S.; flush
with top surface; 4″ × 6″ x 13 SWG mesh
reinforcement 1″ from bottom of slab; 6′6″
span restrained.|150 psf|2 hrs|||7|1, 3|2| |F/C-4-RC-12|4″|4″ deep (2380 psi) concrete deck;
3″ × 11/2″ × 4 lbs R.S.J.; 2′6″ C.R.S.; flush
with top surface; 4″ × 6″ x 13 SWG mesh
reinforcement 1″ from bottom surface;
6′6″ span restrained.|150 psf|1 hr
3 min|||7|1, 2|1| |F/C-4-RC-13|41/2″|41/2″ thick (5200 psi) deck;1/4″ reinforce-
ment bars at 71/4″ pitch with7/8″ cover;3/8″
main reinforcement bars at 33/4″ pitch
perpendicular with1/2″ cover; 13′1″ span
restrained.|140 psf|2 hrs|||7|1, 3|2| |F/C-4-RC-14|41/2″|41/2″ deep (2525 psi) concrete deck;1/4″
reinforcement bars at 71/2″ pitch with7/8″
cover;3/8″ main reinforcement bars at
33/8″ pitch perpendicular with1/2″ cover;
13′1″ span restrained.|150 psf|42 min|||7|1, 5|2/3| |F/C-4-RC-15|41/2″|41/2″ deep (4830 psi) concrete deck;
11/2″ × No.

CBC § 1.3.2 Medium relevance — show source text

See Section R404.1.3.2 for minimum reinforcement required for foundation walls supporting above-grade concrete walls.|

TABLE R404.1.3.2(2)—MINIMUM VERTICAL REINFORCEMENT FOR 6-INCH NOMINAL FLAT CONCRETE BASEMENT WALLSb, c, d, e, g, h, i, j, k	Col2	Col3	Col4	Col5
MAXIMUM UNSUPPORTED WALL HEIGHT (feet)	MAXIMUM UNBALANCED BACKFILL HEIGHTf (feet)	MINIMUM VERTICAL REINFORCEMENT-BAR SIZE AND SPACING (inches)	MINIMUM VERTICAL REINFORCEMENT-BAR SIZE AND SPACING (inches)	MINIMUM VERTICAL REINFORCEMENT-BAR SIZE AND SPACING (inches)
MAXIMUM UNSUPPORTED WALL HEIGHT (feet)	MAXIMUM UNBALANCED BACKFILL HEIGHTf (feet)	Soil classesa and design lateral soil (psf per foot of depth)	Soil classesa and design lateral soil (psf per foot of depth)	Soil classesa and design lateral soil (psf per foot of depth)
MAXIMUM UNSUPPORTED WALL HEIGHT (feet)	MAXIMUM UNBALANCED BACKFILL HEIGHTf (feet)	GW, GP, SW, SP 30	GM, GC, SM, SM-SC and ML 45	SC, 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.

Frequently asked questions

What exactly is the "sectional area" the code uses to compute 0.003 × area?

The sectional area is the gross cross‑section of the wall (thickness × unit length). The code gives the factor 0.003 multiplied by that sectional area as the minimum total reinforcement requirement in § 7.4.4.1.

Can I use joint (ladder) reinforcement to satisfy the minimums?

No. The code expressly prohibits joint reinforcement from being used as the principal distributed reinforcement; use continuous deformed bars or approved splices counted as continuous. See § 7.4.4.1.5 and § 7.4.4.1.1.

How far must trim bars extend past an opening?

Trim bars required around openings larger than 16 inches must extend not less than 48 bar diameters, but in no case less than 24 inches beyond the corners of the opening. See § 7.4.4.1.3.

Is the 24‑inch spacing limit absolute?

The 24‑inch spacing limit is the general maximum for both horizontal and vertical reinforcement per § 7.4.4.1, but the code imposes a 16‑inch vertical spacing limit for reinforced hollow‑unit masonry when bond other than running bond is used (open‑end units). Also, special exceptions (e.g., freestanding nonbearing walls) allow up to 4‑ft horizontal spacing under the stated conditions. See § 7.4.4.1.

Where does the CBC state these TMS 402 changes are adopted?

The CBC adopts/replaces the TMS language via the amendment in § 2106A.1.4; that CBC section contains the replacement wording for TMS 402 § 7.4.4.1 used in California. See § 2106A.1.4.

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California Building Code