Concrete Masonry Units (CMU) vs. Standard Modular Brick
Comparing 2 standards across 16 specifications. 16 key differences identified.
Concrete Masonry Units (CMU), commonly called cinder blocks or concrete blocks, are standardized hollow load-bearing structural blocks governed by ASTM C90. A standard nominal 8×8×16-inch block is manufactured to actual dimensions of 7-5/8 × 7-5/8 × 15-5/8 inches (194 × 194 × 397 mm), designed to incorporate standard 3/8-inch (9.5 mm) mortar joints into a precise 8-inch modular grid.
Standard Modular Clay Brick under ASTM C216 is the benchmark face brick standard for architectural veneer construction. Manufactured to actual dimensions of 3-5/8 × 2-1/4 × 7-5/8 inches (92 × 57 × 194 mm), three modular brick courses with standard 3/8-inch mortar joints equal exactly 8.0 inches in vertical height, perfectly matching the 8-inch height of backing CMU blocks.
Specification Comparison Table
16 Parameters| Parameter / Spec | ||
|---|---|---|
|
Governing Standard
|
ASTM C90 / NCMA TEK / CSA A165.1 | — |
|
Standard 8" Block (Nominal)
|
8 × 8 × 16 inches (203 × 203 × 406 mm) | — |
|
Standard 8" Block (Actual)
|
7-5/8 × 7-5/8 × 15-5/8 inches (194 × 194 × 397 mm) | — |
|
Standard Mortar Joint Thickness
|
3/8 inch (9.5 mm) bed and head joints | — |
|
4" Stretcher Block (Actual)
|
3-5/8 × 7-5/8 × 15-5/8 inches (92 × 194 × 397 mm) | — |
|
6" Stretcher Block (Actual)
|
5-5/8 × 7-5/8 × 15-5/8 inches (143 × 194 × 397 mm) | — |
|
12" Stretcher Block (Actual)
|
11-5/8 × 7-5/8 × 15-5/8 inches (295 × 194 × 397 mm) | — |
|
Compressive Strength Minimum
|
ASTM C90 requires a minimum average net-area compressive strength around 1,900 PSI (13.1 MPa); most manufactured units test well above this, commonly in the 2,000–2,800 PSI range | — |
|
Governing Standards
|
— | ASTM C216 (Facing Brick) / ASTM C62 / BIA Technical Notes |
|
Modular Brick (Actual)
|
— | 3-5/8 × 2-1/4 × 7-5/8 inches (92 × 57 × 194 mm) |
|
Modular Brick (Nominal)
|
— | 4 × 2-2/3 × 8 inches (102 × 68 × 203 mm) including 3/8" joint |
|
Three-Course Rule
|
— | 3 courses of modular brick + 3 mortar joints = exactly 8.0 inches (203 mm) |
|
Standard Brick Non-Modular (Actual)
|
— | 3-3/4 × 2-1/4 × 8 inches (95 × 57 × 203 mm) |
|
Queen Size Brick (Actual)
|
— | 3.0 × 2-3/4 × 9-5/8 inches (76 × 70 × 244 mm) |
|
King Size Brick (Actual)
|
— | 3.0 × 2-5/8 × 9-5/8 inches (76 × 67 × 244 mm) |
|
Standard Mortar Joint
|
— | 3/8 inch (9.5 mm) concave or V-joint tooling |