HomeKnowledgeConcrete Masonry Unit (CMU) — 8×8×16 Standard
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Concrete Masonry Unit (CMU) — 8×8×16 Standard

Updated Mar 25, 2026
Standard hollow concrete block, 8-inch nominal width. Most common masonry unit for commercial and residential walls.

Standard CMU: 7-5/8 x 7-5/8 x 15-5/8 in actual. Weight: 38-43 lbs. Compressive strength: 1,900 psi min per ASTM C90. Three types by moisture control: Type I (moisture-controlled), Type II (non-moisture-controlled). Normal weight (125+ pcf) or lightweight (<105 pcf). Hollow cores accept vertical rebar (typically #4 or #5) with grout fill. Face shell thickness: 1.25 in min. Web thickness: 1 in min. Fire resistance: 4-hr rating for 8 in solid grouted with normal weight aggregate per Table 722.3.2. Cost: $1.50-$3.50/unit. Typical wall cost: $10-$18/sf installed. Mortar: Type S for structural, Type N for non-structural. CSI 04 22 00.

TAGS
CMUconcrete-blockmasonrywallstructural
DETAILS
standard
ASTM C90
fire rating
4-hr (solid grouted)
csi division
04 22 00
unit cost range
$1.50-$3.50/unit
compressive strength
1900 psi min
installed cost range
$10-$18/sf
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