Artificial Grass Rippling And Lifting

What's happening?

Artificial grass is a surfacing material laid on a built base, and it fails for the same reasons a paved surface fails: the base moved, or the surfacing was not restrained. The base under a correctly installed lawn is a compacted sub-base with a fine laying course over it, edged all the way round, with a membrane below to stop growth coming through. Ripples appear when the turf has room to move, not stretched out before fixing, not pinned at the perimeter, or laid over a base that has settled into hollows. Lifting edges are almost always a perimeter fixing problem. Open joints mean the seam tape or adhesive has let go, often because it was laid on a damp base or in cold weather. Heat expansion is real but only shows up as movement if the turf was never restrained.

What usually causes it?

• The turf not stretched and allowed to relax before being fixed, so it settles into waves
• No perimeter fixing: no timber edge, batten or restraint to pin the turf down all the way round
• An inadequate, uncompacted or non-existent sub-base (sometimes turf laid straight onto soil or an old lawn) settling unevenly and leaving hollows the turf drapes into
• Seams joined with tape or adhesive on a damp base or in cold conditions, so the bond never developed
• Thermal expansion in strong sun on turf that has no restraint to expand against
• Insufficient sand infill, leaving the pile unweighted and free to move
• Water ponding under the turf because the base has no fall and the membrane holds water

Is it dangerous?

No, though a rippled surface is a trip hazard on a route people walk regularly, and a lifted edge catches feet and mower wheels. The one thing worth checking is what is trapped under it: turf laid on a base with no fall over a membrane can hold water and go sour, which is a smell and hygiene problem rather than a safety one, particularly where pets use the lawn.

Can I fix it myself?

Work out whether the base or the fixing has failed, because that decides everything. Walk the lawn and press the ripples: if the turf lifts freely off a firm, even base, it is a fixing and tensioning problem. If the base under the ripple is soft, hollow or moves underfoot, the base has failed and re-pinning the surface will not hold. Brushing extra kiln-dried sand into the pile adds weight and helps very mild rippling. Lifting an edge, stretching it out and re-fixing to sound timber is within reach for a small area. A whole lawn that has moved needs taking up.

When should you call a landscaper?

Call a landscaper if the base is soft or has settled, if the ripples cover most of the lawn, if the joins have opened, or if water is sitting under the turf. Those are installation faults rather than wear, and worth raising with whoever laid it if it is recent. Also call where the turf was laid straight onto soil or over an existing lawn: there is no base to re-fix to, and the only durable answer is to build one.

What will the landscaper actually do?

• Lift the turf back to establish whether the sub-base, the laying course or the fixings failed
• Re-lay and re-compact the sub-base and screed the fine laying course to a consistent level and fall
• Install or repair a continuous perimeter edge to fix the turf to on every side
• Re-stretch the turf and let it relax before fixing, so it is not pinned under tension
• Re-form the seams with fresh tape or adhesive on a dry base, matching the pile direction across the join
• Brush in kiln-dried sand infill at the correct rate to weight the pile down, and check that surface water drains through the turf and base rather than ponding on the membrane

Who fixes this

• Artificial grass installation

Questions people ask

Sources & References

1. RHS: Lawns
2. Interpave: Design, construction and maintenance
3. Building Regulations: Approved Document H (drainage and waste disposal)