Can You Lay Artificial Grass Over Grass?

How to lay artificial grass on grass (and why it fails)

Natural turf is a living layer of leaves, thatch and roots sitting in loose topsoil. Cover it with a synthetic carpet and several things happen at once.

• Decomposition and settling. Cut off from light, the grass dies and rots. As the organic layer breaks down, the surface drops unevenly and you see dips, waves and soft spots telegraphing through the turf.
• Odor. Rotting plant matter plus trapped moisture creates a sour, swampy smell, especially in heat. Add pets and the problem multiplies, because urine soaks into organic material that never fully dries.
• Poor drainage. Topsoil and thatch hold water. Turf backing is perforated or fully permeable so water can pass through, but if there is nothing porous below it, water sits under the carpet, which leads to puddles, mildew and loose seams.
• Weeds and regrowth. Aggressive grasses such as bermuda can push runners up through drainage holes and along seams and edges.
• No anchoring. Nails and staples hold poorly in soft, organic soil, so edges lift and seams separate.

Every one of these problems traces back to what is under the turf, not the turf itself. That is why experienced installers spend most of the job on preparation.

The correct prep sequence

Installers vary their methods by soil and climate, but the order of work is broadly the same on residential jobs.

1. Locate utilities and irrigationMark buried lines and cap or reroute sprinkler heads in the turf area before any digging.
2. Remove the existing lawnA sod cutter takes out grass and roots. Most residential jobs excavate a few inches below finished grade to make room for the base.
3. Grade and compact the subgradeThe native soil is shaped so water runs away from the house and toward a drainage point, then compacted so it will not settle later.
4. Add weed fabric where appropriateA geotextile layer can separate soil from stone and slow weed growth, depending on site conditions.
5. Install and compact the aggregate baseCrushed rock, road base or decomposed granite is spread in lifts, watered and compacted with a plate compactor or roller until it is firm and smooth.
6. Roll out, seam and secure the turfPieces are laid with the grain running the same way, seamed with seam tape and adhesive, and fastened at the perimeter with nails or staples.
7. Infill and brushInfill is spread and brushed in to weigh down the carpet, support the fibers and protect the backing.

Pro tip: Ask any installer how deep they excavate, what base material they use and how they compact it. A clear, specific answer is a good sign. “We just put it over what you have” is not.

What goes under the turf

The base layer does the structural and drainage work. Here is how the layers compare.

Seams deserve special attention. On larger yards, pieces are joined with seam tape and a turf adhesive, and the quality of that bond is one of the first things to fail on a rushed job. Our guide to artificial turf glue and seam adhesives explains what professionals use and why. Infill choice matters too, especially for pets and hot climates; see types of artificial turf infill for the options.

Are there any exceptions?

A few situations come close to “over the top” installs, but none of them involve a living lawn left in place:

• Over concrete or pavers. Turf can go over a sound hard surface with a drainage pad or foam underlay, since the slab will not settle or rot. Drainage still has to be planned.
• Temporary event turf. Short-term rolls laid for a party or display are not meant to last and are removed afterward.
• Very small decorative pieces. A mat on a balcony or in a planter is a product, not an installation.

For a yard you plan to live with, the lawn comes out and a base goes in.

Getting it done right

Excavation, compaction and seaming take equipment and experience. Sod cutters, plate compactors, power brooms and turf cutters are standard on professional jobs, and crews who install turf every week know how to read drainage on a site and how to hide seams. If you want a surface that stays flat, drains and holds up to kids and dogs, connect with a vetted crew for artificial turf installation and ask them to walk you through their prep plan before work begins.