What the numbers mean

No. 57 and No. 89 are aggregate gradations, not brand names. Both are crushed, angular stone that locks up under compaction. They behave differently because of particle size and void structure.

No. 57 stone

  • Typical size: about 1 inch down to 1/2 inch.
  • Performance: high load capacity with large, connected voids for fast drainage.
  • Best use: structural base layer over soil or geotextile. Not as easy to screed perfectly smooth on its own.

No. 89 stone

  • Typical size: about 3/8 inch down to fines retained above sand.
  • Performance: compacts tighter and screeds cleaner with fewer surface highs and lows.
  • Best use: top course to refine grade above a stronger, more open base.

How to choose No. 57 vs No. 89

  • Loads and traffic: heavy foot traffic, carts, or equipment favor a No. 57 base for strength. Light residential lawns can use No. 89 as a cap for finish.
  • Finish tolerance: putting green or play areas need a smooth, even plane. Cap No. 57 with a thin No. 89 layer to hit tight tolerances.
  • Drainage priority: wet climates, clay soils, or flat sites benefit from No. 57 in the base to keep voids open.
  • Slope and grading: on steeper grades, No. 57 interlocks well. Use No. 89 only as a thin top course to avoid slippage during compaction.
  • Availability and cost: use locally available crushed, angular stone that meets the gradation. Avoid rounded pea gravel, which does not lock up.

Recommended build-ups that work

1) Residential lawn, balanced performance

  • Geotextile over prepared subgrade if soil is soft or clayey.
  • 3 to 4 inches No. 57 base, compacted in 2 inch lifts.
  • 1/2 to 1 inch No. 89 top course for smooth screed.
  • Optional thin angular sand dressing for micro-leveling only if needed, kept permeable.

2) High traffic or cart loads

  • Geotextile separator.
  • 4 to 6 inches No. 57 base, compacted in lifts.
  • 3/4 inch No. 89 top course, tightly screeded to tolerance.

3) Poor drainage or expansive clay

  • Nonwoven geotextile over stable, proof-rolled subgrade.
  • 4 inches No. 57 minimum for open-void drainage.
  • Perimeter drain or underdrain where water has no exit.
  • 1/2 to 3/4 inch No. 89 for final plane.

This hybrid approach delivers the muscle of No. 57 and the finish of No. 89 so artificial turf performs and drains as designed.

Compaction, grading, and tolerances

  • Compaction: target a dense, stable base. Compact in 2 inch to 3 inch lifts with a plate compactor or roller until refusal.
  • Flatness: hold final grade within about 1/4 inch over 10 feet for landscape turf. Tighter for putting greens.
  • Slope: 1 to 2 percent away from structures is a practical target when site design allows.
  • Moisture: lightly moisten stone before compaction to lock particles without pumping fines.

Drainage and geotextile guidance

  • Use angular, washed stone to preserve permeability. Excess fines can choke voids.
  • Install a separator geotextile when soil is soft, silty, or clayey. It stops stone migration and keeps drainage consistent.
  • Provide an exit path for water. Tie the base to daylight or a drain system where needed.
  • Avoid pea gravel. Rounded particles reduce interlock and stability.

Material checklist

  • Crushed, angular No. 57 stone for base strength and drainage.
  • Crushed, angular No. 89 stone for the screed layer.
  • Geotextile separator appropriate for soil conditions.
  • Compaction equipment sized for the area.
  • Screed boards, straightedges, and a laser level for control.

Common mistakes to skip

  • Using only No. 89 on weak subgrades. It compacts smooth but lacks base strength alone.
  • Overfilling with fines or decomposed granite that block water.
  • Skipping geotextile on clay soils, which leads to pumping and settlement.
  • Leaving no drainage outlet, forcing water to sit under the turf.

Bottom line: No. 57 builds the backbone. No. 89 perfects the surface. Use them together with intent and your artificial turf will stay flat, fast draining, and durable.