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Edger

A hand tool used to round off and finish the edges of concrete slabs to prevent chipping

An edger is a hand tool with a curved blade used to round off and finish the edges of concrete slabs. The rounded edge (typically 1/4 to 1/2 inch radius) prevents corners from chipping and provides a finished appearance. Edging is done after floating but before final troweling.

Why It Matters

Sharp 90-degree edges on concrete slabs chip easily under impact or freeze-thaw cycles. A rounded edge is much more durable—the curved profile distributes impact forces and provides no sharp corner to break off. Beyond durability, edging gives concrete a professional finished look. Unedged slabs look incomplete and amateur.

Edging requires timing. Too early, and the edge slumps and loses shape. Too late, and the tool tears rather than smooths concrete. The concrete should be firm enough to hold the curved profile but soft enough to work easily—usually the same time you'd begin power troweling or hand troweling the main surface.

Technical Details

Edger types:

  • Walking edger: 4-6 foot long, worked while standing
  • Hand edger: 6-10 inches long, worked from knee or board
  • Radius: 1/4 inch (small radius, sharper edge) to 1/2 inch (large radius, more durable)
  • Material: Steel for professional work, plastic for DIY acceptable

Edging technique:

  1. Wait until concrete will hold the shape—test in inconspicuous spot
  2. Run edger along form, keeping blade flat and applying moderate pressure
  3. First pass establishes the curve
  4. Subsequent passes smooth and compact
  5. Work from both sides of forms if accessible
  6. Use edger to cut away any mortar stuck to form faces

For exposed aggregate finishes, edge before washing off the surface paste—edging afterward leaves an unfinished-looking edge with exposed aggregate.

Interior slabs that will receive floor coverings may not need edging—the finished floor hides the edge. Exterior slabs, garage floors, and any exposed edges should be edged for durability and appearance.

After form removal, some contractors touch up edges with a rub brick to remove any minor imperfections or formwork marks.

  • Finishing - Overall process edging is part of
  • Trowel - Tool used after edging
  • Groover - Similar tool for cutting control joints

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