Why you usually skip a sub-base on hardscape

Concrete and pavers already act as a stable, compacted platform. Building a new aggregate sub-base on top adds height, can trap water, and rarely improves performance. For artificial grass over concrete base or pavers, focus on drainage, comfort, and clean attachment instead of a thick stone base.

Exceptions are rare and tied to structural problems like severe heaving, major cracking, or ponding that cannot be corrected with minor repairs, leveling, or underlayment. Fix those issues first.

What to put between concrete or pavers and the turf

Drainage and slope check

  • Confirm slope of roughly 1 to 2 percent toward a drain or edge. Water should have a clear path off the surface.
  • On concrete with no drain path, add weep holes where appropriate and allowed, or route water to an edge with a low profile channel. Do not block existing drains.
  • Do not glue across expansion joints. Leave joints free to move and allow water relief.
  • For pavers, clean and re-sand joints so water can pass through. Address sunken or high pavers before turf.

Underlayment options

  • Drainage mat or mesh: Low profile, ventilated underlayment that lifts turf off the slab, improves airflow, and speeds water evacuation. Ideal for patios, balconies, rooftops, and pavers. Choose UV stable, exterior rated material.
  • Shock or foam pad: 8 to 20 mm thickness improves comfort and can help meet play area needs. Use a perforated or highly permeable pad and pair it with perforated turf to keep flow rates high.

Edge restraint and attachment

  • Perimeter options include treated wood or composite strips mechanically fastened to concrete, metal edging systems, or compatible construction adhesives at the perimeter. Choose a method that holds the edge without blocking drainage paths.
  • Use moisture curing polyurethane turf adhesive on seaming tape for seams. Avoid full surface glue downs so water is not trapped.

Step by step install over concrete or pavers

  1. Inspect and plan: Map slope, drains, and expansion joints. Set the pile direction for how you want the grass to look from main viewpoints.
  2. Clean and prep: Remove debris, oils, and loose material. Degrease slick spots. For minor low areas, use an exterior rated patch or leveling compound and feather smooth.
  3. Repair issues: Replace broken pavers, grind high spots, and fill small cracks on concrete. Solve ponding before moving on.
  4. Edge setup: Install perimeter restraint strips where needed and ensure water can exit under or around the edge.
  5. Underlayment: Roll out drainage mat or foam pad. Stagger joints, lay tight, and tape seams per manufacturer guidance. Keep underlayment clear of drains and joints.
  6. Dry fit turf: Roll out turf, let it relax, align grain, and trim to fit. Leave slight relief over expansion joints.
  7. Seam the panels: Use seaming tape with polyurethane adhesive. Keep adhesive off drain paths and off the face yarn.
  8. Perimeter attachment: Adhere turf at the perimeter in controlled beads or fasten to your edging system. Do not bridge expansion joints with continuous glue.
  9. Infill: Broadcast kiln dried silica or specialty infill at the specified rate, commonly 1 to 2.5 pounds per square foot depending on pile height and product. For pets, consider antimicrobial or zeolite blends. Work infill in with a stiff broom or power brush.
  10. Groom and check: Brush pile upright, top off infill if needed, confirm drains are clear, and verify edges are tight.

Special cases and pro tips

Pets and kennels

  • Prioritize a high flow drainage mat, perforated turf backing, and deodorizing infill. Rinse access matters, so keep water routes open.
  • Avoid over gluing. Leave strategic gaps in adhesive beads so rinse water reaches drains.

Play areas

  • Use a tested shock pad system sized to your target fall height. Confirm pad permeability and do not block drain paths with adhesives.
  • Verify local code requirements before install.

Rooftops and balconies

  • Check structural load limits, wind uplift details, and fire requirements. Many projects use a loose lay system with perimeter restraint and ballast from infill.
  • Do not puncture waterproof membranes. Use compatible adhesives only where approved by the membrane manufacturer.

Over pavers

  • Level telegraphed joints with a thin screed or choose a pad that spans minor undulations. Keep joint pathways open for vertical drainage.
  • Edge restrictions are key on modular paver fields. Consider metal edging anchored to the outer concrete border.

Common mistakes to avoid

  • Laying turf directly on slick concrete without a drainage or comfort layer, which can trap moisture and flatten the feel.
  • Gluing across expansion joints or covering drains, which restricts movement and water flow.
  • Skipping edge restraint, which leads to curling and creep.
  • Under infilling, which reduces fiber support and speeds matting.
  • Using non permeable foam that blocks water.

Materials checklist

  • Permeable drainage mat or perforated shock pad, exterior rated and UV stable.
  • Artificial turf with perforated backing suited for the intended use, landscape, pets, or play.
  • Seaming tape and moisture curing polyurethane turf adhesive.
  • Perimeter edging, treated wood or composite strips, metal edging, or compatible adhesives.
  • Infill, kiln dried silica, coated sand, TPE, or zeolite for pets.
  • Tools, stiff broom or power brush, utility knife with sharp blades, roller, caulk gun, drill and bits, solvent wipes for cleanup.

When a true sub-base makes sense

  • Replacing failed hardscape with new turf areas where concrete or pavers are removed. You will need a compacted aggregate base on native soil.
  • Severely damaged slabs where repair is not practical. Demolish, rebuild base, and pour new hardscape or install turf over a proper aggregate base.
  • Height match requirements that need more than a thin leveling course. In these cases, consider rebuilding the surface rather than stacking materials.

Cost and timeline

Expect added materials for artificial grass over concrete base or pavers to range roughly from 1.25 to 5.50 dollars per square foot for underlayment, adhesive, tape, and infill, plus labor that varies by market and access. Small patios and walkways often install in one day after prep. Larger or complex rooftop and play projects may take several days for staging, edge work, and safety testing.