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Strike-Off

The initial leveling of concrete using a straight board immediately after placement

Strike-off is the initial leveling of concrete using a straight board (screed board) immediately after placement. Moving the board across the concrete surface in a sawing motion removes excess concrete and brings the surface to proper grade. Strike-off is the first critical step in the finishing sequence—everything else builds on a properly struck surface.

Why It Matters

Strike-off establishes grade and removes major high spots. If this step fails, subsequent finishing operations can't correct it. A slab that's 2 inches thick in one area and 6 inches thick nearby can't be fixed with troweling—the damage is done. Professional concrete crews focus intensely on strike-off because they know it determines final quality.

For DIY work, having enough helpers for strike-off is critical. The board must move steadily across wet concrete, requiring coordination and physical effort. Stopping midway allows concrete to stiffen unevenly. Plan to have 2-3 people dedicated to strike-off, with others spreading and raking concrete just ahead.

Technical Details

Strike-off equipment:

  • Screed board: Straight 2x4 or 2x6, aluminum channel, or magnesium extrusion
  • Length: Spans from form to form with 12-18 inch overhang each side
  • Straightness: Critical—bowed boards create uneven surfaces
  • Handles: Optional, help with control and reduce fatigue

Strike-off technique:

  1. Overfill forms slightly (1/2 to 1 inch high)
  2. Place screed on forms at far end of pour
  3. Pull toward yourself with rapid sawing motion
  4. Tilt leading edge slightly up to shear off high spots
  5. Fill low spots immediately and re-strike
  6. Work steadily without stopping

For large slabs without intermediate screeds, laser screeds or vibrating screeds improve efficiency and accuracy. Small residential work typically uses manual methods.

Strike-off timing matters. Concrete must be fluid enough to fill voids as the screed passes, but stiff enough to hold shape afterward. Too wet, and concrete slumps after screeding. Too stiff, and voids remain unfilled.

  • Screeding - Related term, often used interchangeably with strike-off
  • Leveling - Purpose of strike-off operation
  • Screed Board - Tool used for strike-off

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