Can You Put Artificial Turf Over Existing Grass?

This page is for homeowners who have been told, or have read, that they can skip sod removal and save a day of digging and a few hundred dollars. We read four manufacturer installation guides side by side and set out what each requires, why, and what goes wrong first if you leave the grass in place. For the full job sequence, see how to install artificial turf.

What do manufacturer installation guides say about existing grass?

None of the four guides offers leaving the grass as an option. Each starts the same way: take the grass out, take some soil with it, firm up what is left, then build a crushed rock base.

Three details in that table matter more than the headline depth.

The depth is set by the base, not by the grass. The excavation makes room for 3 to 4 inches of rock so the finished turf sits at the height of the patio or path next to it. The Lowe's-hosted guide puts the compacted base 1 to 1.5 inches below an adjoining slab, so the turf's pile brings the surface level. Skip the dig and the whole lawn rises 3 to 4 inches above every edge it meets.

The target is undisturbed soil, not a number. Polyturf's manual removes loose topsoil "down to undisturbed earth" and adds that "where the topsoil is reasonably compacted it can be left." The point is to put the base on something that will not move. Grass, thatch and root-filled topsoil are the opposite of that.

Compaction is specified, and grass cannot be compacted. The guides ask for 80 to 90% compaction. A layer of living plants and roots springs back under a plate compactor and keeps shrinking for months afterward as it rots.

Why do some sites say you can lay turf on grass?

Because it is physically possible, and because a few product types really do go down without a base. The Lowe's-hosted guide says turf over concrete can be glued down and "no base is required." That is true of a slab, which is flat, hard and inert. Readers carry the idea over to a lawn, which is none of those things. Installer blogs that rank for this question usually say it can be done and then list the reasons not to, which leaves readers with a yes they should not act on. Our answer for a lawn you want to last is no; turf on concrete is the case where skipping excavation is correct.

What does the dead grass layer do under turf?

Cover a lawn with turf backing and the grass loses its light. It dies, and the layer of living and dead stems, leaves and roots under it begins to rot. Lawn care calls that layer thatch (not to be confused with the curly fibers in turf that share the name), and extension services measure it. The University of Minnesota says a thatch layer of "one-half inch or less" is usually not a problem in a lawn; UMass Amherst flags thatch above 1/2 to 3/4 inch compressed. So a normal, healthy lawn carries up to about 1/2 inch of organic mat at the soil surface before you count the grass blades above it.

Compare that with the flatness a turf base is built to. Our base preparation target is no gap over 1/4 inch under a 10 ft straightedge. The thatch alone on an ordinary lawn can be twice that tolerance, and it is not even. It is thick where the grass grew well, thin over worn paths, and absent in bare patches. When it rots, each spot drops by a different amount, and turf backing, which is thin and flexible, follows every dip.

The rot is also slow and hard to predict. Minnesota's extension lists "poor soil aeration and waterlogged soils which limit microorganism activity" among the conditions that slow thatch breakdown. A buried, covered, often damp layer is exactly that condition, so settling does not finish in a few weeks and then stop. It keeps going after you have nailed the edges.

What fails first if you skip grass removal?

In the order homeowners usually notice them:

1. Uneven settling. Dips show first in low-angle light and along seams, as the thickest patches of grass and thatch rot away. Seams are where it is most visible, because two pieces of backing pull apart over the low spot. See visible seams.
2. Weeds and grass coming back. Turf backing blocks light, but creeping grasses push runners toward the drainage holes and edges. Without a base or fabric between them and the turf, they reach the surface. Our weeds through turf page covers removal after the fact.
3. Slow drainage and smell. Turf drains through its backing into whatever is below. A crushed base passes water quickly; a mat of dead grass holds it, and organic material held wet under plastic smells. In pet areas the problem arrives fastest, because urine soaks into the rotting layer instead of rinsing through rock. See turf smells and standing water.
4. Edges that do not hold. Every guide nails the turf into compacted base. Driven into a soft mat of roots and rotting thatch, nails have little to grip, so edges lift and the turf creeps.

Our getting quotes guide lists "turf installed over existing grass" as a red flag in a bid for exactly these reasons.

Can you kill the grass and leave it in place?

Killing the grass first solves only the regrowth problem, and only partly. It does nothing for the rot, because dead grass and thatch still decompose, and it does nothing for the height. Polyturf's manual suggests letting the area "dry out for a few weeks" to encourage the grass to die, but the next step in that manual is removal: killing is a way to make sod easier to strip, not a substitute for stripping it. Herbicide timing and fabric placement for stubborn grasses like Bermuda are in our weed barrier guide.

When is it fine to put artificial turf over grass?

When the turf is temporary. Event covers are built for exactly this: one maker of event flooring says its product "can be laid directly on the grass and then easily removed after the event" (Geoplast). Rolled out loose for a wedding, a party, a sales display or a few days of event seating, turf laid on a lawn is a cover, not an installation. Nothing is nailed, nothing has to drain for years, and it comes up before the grass beneath has time to rot. Keep the time short, since the grass under it is without light for as long as it is covered, and expect to rake and water the lawn afterward.

A small loose mat (a pet potty pad, a play mat) on a lawn falls in the same category if you lift and move it. The line is permanence: if it is meant to stay for seasons, the grass has to come out.

What does skipping sod removal actually save?

Less than most people expect, and the saving is in the wrong place. Sod removal and haul-away runs about $0.75 to $2.00 per sq ft in our artificial turf cost breakdown. The excavation also does not remove the need for base: you still have to buy rock, and the guides disagree on how much.

The Lowe's-hosted rule is the lean one. One ton for 100 sq ft at 3 inches works out to about 1.1 tons per cubic yard of finished base, less than the 1.3 tons Star Nursery gives for a loose yard before compaction. Order by your supplier's figure or the calculator rather than by 1 ton per 100 sq ft.

Frequently asked questions

How long does it take grass to die under artificial turf?

The guides we read do not give a time, and none of them relies on it. Killing is not the issue, though. The problem is what happens after the grass dies: the organic layer rots slowly and unevenly under the turf, and the surface follows it down. Remove the grass and that layer goes with it.

Can I put turf over grass if I add sand or base on top?

Adding rock on top of grass raises the lawn 3 to 4 inches above every patio, path and edge it meets, and the grass and thatch still rot underneath the new layer. You get the cost of a base without the stable footing that makes a base work. The guides put the base on compacted soil after the grass is gone, not on top of it.

Do I need to remove all the roots before laying turf?

No. Remove the sod layer and loose topsoil, then compact what is left; Polyturf's manual stops at undisturbed earth and leaves reasonably compacted soil in place. Fine roots below that depth are a small volume. Large woody roots and runners of creeping grasses like Bermuda are worth pulling, since they rot into voids or regrow. Our base preparation page covers sub-grade compaction.

Is laying turf over grass ever done by professional installers?

For permanent residential lawns, not by any installer following the manufacturer guides we read, all of which remove grass and soil first. Short event hires are the exception, because the turf is a temporary cover that comes up within days. If a quote for a permanent lawn says turf goes over existing grass, or does not state an excavation depth, ask why before you sign.

Will weed barrier stop grass growing through turf laid on a lawn?

Fabric slows regrowth, but it does not fix settling or drainage, and laid on live grass it sits on a soft layer that will rot and sink. The guides put fabric on compacted sub-grade or on finished base. Placement and fabric types are compared in our weed barrier guide.