8.2 Brick and CMU Bonds, Reinforcement, and Coursing
Key Takeaways
- Brick positions (stretcher, header, soldier, rowlock, sailor) control both appearance and structural tying; headers tie multi-wythe walls.
- Running bond is standard; stack bond is weakest and requires added horizontal joint reinforcement (min 0.0007 of gross area, max 16 in spacing).
- Nominal CMU height is 8 inches: 3 courses = 24 inches; divide wall height by 8 to count courses.
- Three brick courses equal 8 inches, letting brick veneer align with CMU backup every 8 inches.
- Bond beams carry horizontal rebar; vertical bar lap splices are typically 48 bar diameters with full grout surround.
Bonds, Reinforcement, and Coursing
A masonry bond is the pattern in which units are laid; it determines both appearance and how loads transfer between units. Exam questions test the difference between structural bonding (units actually interlock to tie wythes) and pattern bonding (purely visual face arrangement).
Know the names of the brick positions and orientations because plans and the reference text use them constantly.
Brick Positions
| Position | Description |
|---|---|
| Stretcher | Laid flat, long face exposed (most common) |
| Header | Laid flat, short end exposed; ties wythes together |
| Soldier | Standing vertical, narrow face out (lintels, accents) |
| Rowlock | On edge, end exposed (sills, caps) |
| Sailor | Standing vertical, broad face out |
| Shiner / Rowlock stretcher | On edge, broad face out |
Header courses are the key to structural bonding in solid multi-wythe walls — they physically tie front and back wythes. The soldier course is the classic detail above windows and doors.
Common Bond Patterns
- Running bond: each unit offset 1/2 unit from the course below; no headers. Standard for veneer and CMU.
- Common (American) bond: running bond with a full header course every 5th, 6th, or 7th course to tie wythes.
- Flemish bond: alternating stretchers and headers in every course.
- English bond: alternating full courses of stretchers and headers.
- Stack bond: units aligned vertically (no offset). Weak — requires horizontal joint reinforcement because there is no natural overlap.
Exam trap: stack bond has the lowest lateral strength and the IBC requires added joint reinforcement (minimum area of horizontal reinforcement of 0.0007 times the gross cross-sectional area of the wall, spaced not over 16 inches).
Reinforcement and Coursing Math
Horizontal joint reinforcement (ladder or truss type, ASTM A951) is laid in bed joints, typically every 16 inches (every other CMU course). Vertical reinforcement is rebar grouted into cells.
Coursing uses the nominal 8-inch CMU height: 3 courses = 24 inches (2 feet), so a wall is built to multiples of 8 inches. To find courses in a wall, divide wall height (inches) by 8.
- Worked example: an 8 ft (96 in) CMU wall = 96 / 8 = 12 courses.
- Brick modular coursing: 3 brick courses = 8 inches (each course = 2-2/3 inches with a 3/8-inch joint), so brick and CMU align every 8 inches — important when brick veneers a CMU backup.
Grouting and Cell Reinforcement Rules
Per IBC Chapter 21 / TMS 402 (The Masonry Society code):
- Minimum grout space for fine grout is roughly 3/4 inch; coarse grout needs more clearance around bars.
- Vertical bars must have grout fully surrounding them; lap splices are commonly 48 bar diameters unless engineered otherwise.
- Bond beams (CMU with a notched/knockout web) carry horizontal rebar and act as continuous tie courses, often at the top of wall and at floor lines.
- Reinforcement clear cover in masonry is typically 1-1/2 inches for bars exposed to weather, 3/4 inch otherwise.
A solid two-wythe brick wall must transfer load between the front and back wythes. Which brick position accomplishes the structural tie?
How many courses are in a nominal 8-foot-tall concrete masonry unit wall using standard 8-inch coursing?
Bond Patterns and Structural Bond
Distinguish pattern bond (appearance) from structural bond (how units interlock). Running bond (each unit offset half a unit) is the standard structural bond — staggered head joints distribute load. Stack bond (joints align vertically) is weak structurally and needs added horizontal joint reinforcement. Historic English and Flemish bonds use header courses (units turned end-out) to tie a multi-wythe wall together; modern cavity walls use metal ties instead of headers.
Reinforcement and Coursing Math
Horizontal joint reinforcement (ladder/truss wire) is laid in bed joints, typically every 16 in vertically (every other CMU course). Vertical rebar sits in grouted cells. Coursing example: a CMU course is 8 in high (7-5/8 block + 3/8 joint). A wall 8 ft (96 in) tall = 96 / 8 = 12 courses. Brick modular coursing: 3 courses = 8 in (each ~2-2/3 in).
Grouted Cells and Bond Beams
Reinforced masonry concentrates steel in grouted cells; a bond beam is a horizontal course of channel/knock-out block filled with grout and rebar, acting like a concrete beam over openings and at wall tops/floor lines for lateral (seismic/wind) resistance. Cells with rebar must be fully grouted; cleanouts at the base let inspectors verify before grouting tall lifts (TMS 402/602).
Common Exam Traps
- Trap: Stack bond is as strong as running bond. It is weaker; needs extra reinforcement.
- Trap: A CMU course is 8-5/8 in tall. It is 8 in nominal (block + joint).
- Trap: Headers are only decorative. In multi-wythe walls they structurally tie wythes.
- Trap: Forgetting joint reinforcement spacing (~16 in o.c.).
A CMU wall must be built 10 ft 8 in tall using standard 8-in nominal coursing. How many courses are required?
Wall Ties, Cavity Walls, and Anchorage
In a veneer or cavity wall, the outer wythe is non-structural and must be tied to the backup with corrugated metal ties or adjustable anchors, commonly one tie per ~2.67 SF of wall (and within a set distance of openings). Ties transfer wind and seismic loads to the structure while allowing the cavity to drain. Reinforced grouted walls also anchor to floors and roofs with dowels and bond beams so the whole assembly resists lateral load as a unit. Missing or rusted ties are a frequent cause of veneer bulging and detachment.
Worked Reinforcement-Spacing Check
Example: A spec calls for #5 vertical bars at 48 in o.c. in a CMU wall built of 16-in-long block. 48 in / 16 in = every third cell gets a grouted bar. Horizontal joint reinforcement at 16 in o.c. means every other 8-in course. Laying out the first cell correctly so the 48-in module lands on a cell (not a web) is the practical step crews miss; the inspector verifies bar size, spacing, and full grouting of those cells before the next lift.