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Materials & Specificationsaka: CMUaka: cinder blockaka: concrete blockaka: block

Concrete Masonry Unit

In Plain English

A concrete block used to build walls and structural elements.

Definition

A concrete masonry unit (CMU) is a precast block made from Portland cement, aggregate, and water, used to construct walls, foundations, and structural elements. CMUs come in various sizes, configurations, and strengths for different structural and architectural applications. They can be left exposed, plastered, or faced with other materials.

Why It Matters in Bidding

CMU scope is typically counted by the unit or by wall area, and the bid hinges on getting the block count, mortar, grout, and reinforcement quantities right together. Masonry is labor-intensive, so estimators must price installed cost per square foot and account for productivity factors like wall height, openings, and bond pattern that swing the labor line far more than the block material itself.

Example

An estimator quantifies 6,200 square feet of 8-inch CMU partition wall, converts it to block count, then prices block, mortar, grout for the reinforced cells, and mason labor at an installed rate per square foot for the masonry subcontract.

Related Terms

ConcreteMortarRebarStucco

Frequently Asked Questions

Walls are usually taken off in net square feet of face area after deducting large openings, then converted to block counts using a units-per-square-foot factor for the block size. Estimators add mortar, grout for reinforced or load-bearing cells, rebar, joint reinforcement, and accessories as related quantities.
Block size and weight, wall height requiring scaffolding, number of openings and corners, reinforcement and grouting requirements, and the bond or finish pattern all affect how many units a mason lays per day. Estimators adjust labor rates for these conditions rather than applying a single flat productivity number across all walls.
Yes. Fully grouted or partially grouted reinforced walls require additional grout material, rebar placement, and labor that empty-cell partition walls do not. The structural drawings specify which cells are grouted, so estimators must read the reinforcement schedule before pricing to avoid leaving grout and steel out of the masonry scope.

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