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Materials & Specificationsaka: masonry mortaraka: grout

Mortar

In Plain English

The cement-based paste used to bond bricks, blocks, and stones together in masonry construction.

Definition

Mortar is a workable paste made from cement, sand, and water used to bond masonry units such as brick, CMU, and stone, and to fill the joints between them. Different mortar types (M, S, N, O) have different compressive strengths suited to different applications and exposure conditions. Mortar joint quality significantly affects masonry wall performance and appearance.

Why It Matters in Bidding

Mortar is a small line item by dollar value but a large driver of masonry labor productivity, so estimators should tie mortar quantities to wall area, joint size, and unit type rather than guessing. Specifying the wrong type can fail the spec or compromise wall performance, triggering rework. Color-matched or specialty mortars and cold-weather admixtures also add cost that must be captured during takeoff.

Example

Estimating a CMU exterior wall, the estimator selects Type S mortar per the spec for its higher bond and flexural strength, then adds colored mortar and winter heating costs because the schedule runs into December.

Related Terms

Concrete Masonry UnitCementAggregateStucco

Frequently Asked Questions

They denote decreasing compressive strength: Type M is strongest for below-grade and heavy-load masonry, Type S balances strength and bond for exterior structural walls, Type N suits general above-grade work, and Type O is a low-strength mix for interior or restoration. Estimators price the type the specification requires for each assembly.
Mortar is typically derived from masonry unit counts and wall area, since each brick or block consumes a known volume of mortar based on unit size and joint thickness. Estimators add waste allowance, then account for mixing labor, scaffolding, and any colorant or cold-weather measures that affect both material and labor cost.
Yes. Pigmented and color-matched mortars cost more than standard gray and may require mock-ups for approval. Cold-weather masonry needs heated materials, enclosures, and admixtures to protect against freezing, all of which add labor and equipment. Estimators should flag these conditions from the specs and schedule when building the masonry price.

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