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Floating

Finishing operation of smoothing freshly screeded concrete with a flat tool to embed aggregate and fill voids

Floating is the finishing operation of smoothing freshly screeded concrete with a flat tool (float) to embed aggregate, remove high and low spots, and prepare the surface for final finishing. Floating follows screeding and precedes troweling or brooming in the standard finishing sequence.

Why It Matters

Floating bridges the gap between rough screeding and final finishing. Without floating, the surface retains the ridges and voids left by screeding—too rough for troweling and uneven for brooming. Floating pushes coarse aggregate below the surface, fills voids with paste, and creates a uniform surface ready for the final texture.

Timing is critical. Float too early and you push aggregate down but bring excess water up, weakening the surface. Float too late and the concrete is too stiff to work, leaving an unfinished appearance. The window is typically 15-45 minutes after screeding, depending on temperature and mix design.

Technical Details

Float types:

  • Wood float: Traditional tool, creates slightly rough texture. Used when a non-slip surface is desired without brooming. Opens surface pores for better curing compound penetration.
  • Magnesium float: Lightweight metal float, produces smoother surface than wood. Most common for residential flatwork. Doesn't drag or pull concrete like wood can.
  • Bull float: Large flat blade (3-4 feet wide) on a long handle. Used immediately after screeding to smooth large areas without walking on concrete. First floating operation on any slab.
  • Power float: Mechanical rotating float for large commercial slabs. Faster and more consistent than hand floating.

Bull floating technique:

  1. Push float away with leading edge slightly raised
  2. Pull back with trailing edge slightly raised
  3. Overlap passes by half the float width
  4. Work perpendicular to screed direction
  5. Complete within 15-20 minutes of screeding

Hand floating technique:

  1. Wait until bleed water disappears and concrete supports kneeling
  2. Work in sweeping arcs with flat blade
  3. Apply even, moderate pressure
  4. Fill any remaining voids or depressions
  5. Surface should be uniformly smooth and free of aggregate at surface

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