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what to put under artificial grass

You generally want a firm, free‑draining, weed‑resistant base under artificial grass—never just bare soil.

The Ideal Layer Stack (Quick Scoop)

For a typical garden or yard, a common build‑up is:

  1. Excavated, compacted soil
    • Remove existing turf/roots to around 7–10 cm depth so the new layers sit flush with surrounding areas.
 * Lightly compact the soil so it doesn’t settle later and cause dips.
  1. Sub‑base: crushed stone / road base
    • Use MOT Type 1, class II road base, crushed granite, or similar angular gravel (not round pea gravel).
 * Typical depth: about 5–8 cm for normal foot traffic; go thicker if you expect cars or very heavy use.

 * Compact it in thin layers with a plate compactor so it locks together and still drains.
  1. Levelling layer: sharp sand or stone dust
    • Add 1–2 cm of sharp sand , granite dust, or stone fines to smooth and fine‑tune the level.
 * Avoid soft builders’ sand that holds water and shifts easily.
  1. Weed membrane (permeable fabric)
    • Lay a geotextile weed barrier that lets water through but blocks weed growth.
 * Do not use plastic sheet or tarp; it traps water and can cause smells and mold.
  1. Optional: foam underlay or shock pad
    • On concrete or decking, use a drainage foam underlay (about 5–10 mm) to soften the feel and even out small imperfections.
 * For kid play areas or where falls are likely, add a thicker safety shock pad for extra cushioning.
  1. Infill after the turf is laid
    • Once the grass is down, brush in silica sand or a specialist turf infill to help blades stand up, add weight, and improve stability.

What Changes by Situation?

  • Over bare soil (most backyards)
    Crushed stone/gravel sub‑base + thin sharp sand/stone dust + weed membrane is usually the best combo for stability and drainage.
  • Over concrete or paving
    Skip the gravel; use a free‑draining foam underlay or shock pad directly on the hard surface, then lay the turf and infill.
  • Dog runs / heavy use
    Go for a firmer, very well‑draining base (crushed stone + granite/stone dust instead of too much sand) so urine drains quickly and the surface doesn’t rut.
  • Putting greens
    Same basic idea, but the top levelling layer is often very carefully graded fine stone so ball roll is smooth and predictable.

Things Not to Put Under Artificial Grass

  • Plain topsoil alone (moves, gets muddy, and creates dips).
  • Plastic sheeting/tarps for “weed control” (blocks drainage, holds smells).
  • Thick layers of soft builders’ sand as the main base (shifts and holds water).

Simple Example Build

For a small DIY lawn:

  • Excavate old grass about 8 cm deep and compact the soil.
  • Lay 5–6 cm of compacted MOT Type 1 or similar crushed stone.
  • Add 1–1.5 cm of sharp sand or granite dust, screed it smooth, and compact lightly.
  • Lay a permeable weed membrane.
  • Install the turf, secure edges, and brush in silica sand infill.

TL;DR: Put a compacted crushed‑stone sub‑base, a thin sharp‑sand or stone‑dust levelling layer, and a permeable weed membrane under artificial grass; on concrete, swap the stone for a drainage foam underlay.

Information gathered from public forums or data available on the internet and portrayed here.