Keyway

Keyway is a recess or groove formed in concrete or masonry to provide a mechanical connection between two sections, enhancing shear resistance and preventing lateral movement.

Keyways are critical in the construction of foundations, walls, and joints. You’ll most commonly see them where a footing meets a foundation wall. The groove in the footing creates a tongue-and-groove connection with the wall pour, which resists the lateral pressure of backfill soil pushing against the foundation.

Where Keyways Show Up on a Job Site

• Foundation walls: A keyway cast into the top of a footing locks the wall pour in place and prevents sliding at the cold joint.
• Retaining walls: The shear connection helps the wall resist soil pressure without relying solely on rebar dowels.
• Concrete slabs: Keyways at construction joints between slab sections reduce differential settlement and movement.
• Dam and water-control structures: Keyways prevent water from migrating along the joint between two pours.

Practical Example

On a residential foundation job, the crew places a beveled 2x4 (or a manufactured keyway strip) into the wet footing concrete before it sets. Once the footing cures and the strip is removed, the groove remains. When the wall is poured on top, concrete fills the keyway and creates a mechanical interlock. This is faster and cheaper than drilling and epoxying additional dowels after the fact.

Accurate concrete estimates keep your margins intact on foundation work. Projul’s live construction cost database gives you real-time material pricing so your bids reflect what you’ll actually pay.

For more on concrete best practices, see our concrete best practices guide.