What drives base depth

Your site conditions decide the build, not guesswork. Depth is set by load, drainage, soil, and climate. Get those right and your turf stays flat, drains clean, and resists movement.

  • Foot traffic and load: More feet, wheels, or equipment require a thicker, denser base.
  • Soil type: Clay swells and softens. Sand drains fast but can shift. Each needs a different base profile.
  • Climate: Freeze thaw cycles can heave thin bases. Cold regions benefit from added thickness and tighter compaction.
  • Drainage and slope: Poor percolation demands more depth and sometimes underdrains. Maintain 1 to 2 percent surface fall away from structures.
  • Intended use: Lawns, pets, play areas, and sports each have different performance targets and impact needs.

Recommended depths by scenario

  • Residential lawns, light to moderate use: A mid-depth compacted aggregate base is appropriate for most yards.
  • Pets, play zones, high traffic paths, clay soils, or cold regions: Increase thickness for stability, drainage capacity, and frost resistance. Consider a shock pad in play areas for fall attenuation.
  • Driveway margins and utility cart paths: A thicker, well-compacted profile resists edge rutting and rolling loads.
  • Rooftops and balconies: Skip loose aggregate. Use drainage boards or panels and a pad system designed for over-structure installs.

Base materials that work

  • Crushed stone fines mix: Use 3/4 inch minus or Class II road base that locks up under compaction. In arid regions, decomposed granite can perform well.
  • Avoid round rock: Pea gravel and river rock do not interlock and will migrate.
  • Screenings caution: Pure limestone screenings can get tight and impede drainage if overused. Blend with angular aggregate.
  • Geotextile and geogrid: A nonwoven geotextile under the base separates soil from aggregate. In weak clay, add a light geogrid layer to reduce pumping.

Compaction targets

  • Lift thickness: Place base in thin lifts, about 2 inches loose, and compact each layer before the next.
  • Moisture: Base should be damp, not muddy, before compacting.
  • Density: Compact to a hard, unyielding surface. Aim for roughly 90 to 95 percent of modified Proctor where measurable.
  • Equipment: Use a plate compactor or roller sized to the area. Edge compaction is critical around borders and transitions.

Build sequence

1. Pre-checks

  • Call 811 to locate utilities.
  • Walk the site after rain to spot drainage issues before you dig.

2. Excavation

  • Remove sod, roots, and organic soils down to firm subgrade.
  • Cut deep enough to accommodate base and turf so finished elevation meets adjacent hardscapes.
  • Maintain a consistent 1 to 2 percent slope away from structures.

3. Subgrade prep

  • Compact native soil to refusal. If subgrade pumps or smears, add geotextile and, in problem spots, a light geogrid.
  • For saturated areas, plan a French drain or perforated pipe to daylight or a dry well.

4. Base installation

  • Install angular crushed aggregate in thin lifts. Compact each lift thoroughly.
  • At edges, use a rigid border or bender board to hold grade and prevent creep.
  • Top off with a fine leveling course, then final compact and proof roll.

5. Drainage and pads

  • Use drainage mats or panels over concrete and rooftops.
  • Add a shock pad under play turf to meet fall ratings.

Depth adjustments for climate and soils

  • Freeze thaw zones: Increase base thickness and prioritize free-draining aggregate. Keep water moving and out of the frost zone.
  • Heavy clay: Thicker base, geotextile separation, and sometimes underdrainage prevent pumping and settlement.
  • Well-drained sands: Depth can be conservative if traffic is light, but compaction and edge restraint still matter.

Quick quantity calculator

Volume in cubic yards = Area (sq ft) × Depth (in) ÷ 324. Aggregate typically weighs 1.4 to 1.6 tons per cubic yard.

  • Example: 500 sq ft at 4 inches depth = 500 × 4 ÷ 324 ? 6.2 cubic yards, or about 9 to 10 tons.

Common mistakes to avoid

  • Cutting depth in clay or cold climates to save cost, then fighting heaving and ruts later.
  • Skipping lift compaction and trying to compact the full depth at once.
  • Using round stone that will not lock up.
  • Leaving organic topsoil under the base.
  • Ignoring drainage and installing flat against structures.

When you can go thinner

On stable, free-draining native sand with light foot traffic, a conservative reduction can work if compaction is dialed and edges are restrained. Test the subgrade, verify drainage, and do not compromise on lift compaction.

Want a site-specific plan

Every property is different. Book a quick assessment with a FusionTurf pro for a depth and material spec that hits your performance target the first time.