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Sitework & Earthworkaka: concrete retaining wallaka: MSE wallaka: block wall

Retaining Wall

In Plain English

A wall built to hold soil in place where the ground changes elevation — keeping hillsides from sliding down.

Definition

A structure designed to hold back soil and support a grade change, allowing different elevations on either side of the wall. Retaining wall types include gravity walls (rely on weight), cantilever walls (reinforced concrete), MSE walls (mechanically stabilized earth), and soldier pile walls. Proper drainage behind the wall (weep holes or drainage aggregate) is essential to prevent hydrostatic pressure buildup.

Why It Matters in Bidding

Retaining walls are high-risk, high-cost sitework items where the bid must capture not just the wall but excavation, backfill, drainage, and engineering that owners often underestimate. Estimators must identify the wall type and design responsibility early, because a delegated-design MSE or cantilever wall carries very different material, reinforcement, and submittal costs than a simple segmental block wall.

Example

Pricing a sloped commercial site, the estimator takes off 220 linear feet of cantilever retaining wall, then adds drainage aggregate, weep holes, geogrid, and structural backfill that the wall section requires but the plan view does not show.

Related Terms

ShoringGeotextileFrench DrainGrading

Related Tools & Templates

Retaining Wall Design Specs

Frequently Asked Questions

Cost depends on wall type, height, soil conditions, and drainage. Beyond the wall material itself, estimators must carry excavation, structural backfill, drainage aggregate, weep holes or pipe, reinforcement, and any geogrid. Height matters because taller walls often trigger engineered designs and added structural requirements that scale cost steeply.
It varies. Some walls are fully detailed by the engineer of record, while proprietary segmental and MSE systems are often delegated-design, requiring the contractor or supplier to provide stamped calculations and shop drawings. Estimators should confirm design responsibility during bidding, since delegated design adds engineering and submittal cost.
Without drainage, water builds hydrostatic pressure that can fail the wall, so plans require weep holes, drainage aggregate, and often perforated pipe. These items add real material and labor cost yet are easy to miss because they appear in wall sections rather than the plan view, creating scope gaps if overlooked.

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