How much does the base for artificial grass cost? (UK guide)

The short answer

The base for artificial grass — the excavation, weed membrane and compacted stone sub-base — typically costs somewhere around £20 to £40 per square metre in materials and labour combined, though it varies with depth, soil and access. The build-up usually consists of a layer of crushed stone such as MOT Type 1 topped with a finer grano dust or sharp-sand laying course, over a weed membrane, all compacted to a true, free-draining surface. The base is often a similar cost to the grass itself, and getting it right is what stops the lawn from dipping, holding water or letting weeds through. Cutting back on the base is the most common false economy in an artificial lawn.

The base is the part you never see but pays for the lawn's flatness, drainage and longevity. It is also where quotes most often differ, so it is worth understanding what it should contain.

Artificial grass base

Indicative base cost~£20–£40 per m2
Main stone layerMOT Type 1 crushed stone
Laying courseGrano dust or sharp sand
MembraneGeotextile weed barrier
Typical depthOften around 75–100 mm of stone

What the base is made of

A proper artificial-grass base is a layered structure designed to be flat, stable and free-draining. From the ground up it usually comprises:

Excavated bed: existing turf and soil dug out to make room for the sub-base, with the spoil removed.
Weed membrane: a geotextile sheet laid to suppress weed growth from below.
Sub-base stone: a layer of crushed angular stone such as MOT Type 1, spread and compacted in passes to a firm, level base — often in the region of 75 to 100 mm thick, deeper where drainage is poor.
Laying course: a finer layer of grano dust (granite fines) or sharp sand, screeded smooth, to give the grass a true surface to sit on.
A second membrane: sometimes laid on top of the stone, beneath the grass, for extra weed protection.

Each layer has a job — the stone gives strength and drainage, the laying course gives smoothness, and the membranes keep weeds out. Skimp on any of them and the lawn suffers.

Base element	Material	Purpose
Sub-base	MOT Type 1 crushed stone	Strength, stability, drainage
Laying course	Grano dust or sharp sand	Smooth, level surface for the grass
Weed membrane	Geotextile sheet	Suppress weeds from below
Excavation	Dig out + spoil removal	Make room for the base build-up
Compaction	Vibrating plate (wacker)	Firm, settled, true surface

Indicative base build-up for guidance only. Layer depths and exact materials vary with soil type, drainage and intended use.

What the base costs and why it varies

As a rough guide, the base accounts for somewhere around £20 to £40 per square metre once you include excavation, materials and the labour to build and compact it. Several things move that figure:

Excavation depth: a deeper dig for poor-draining clay needs more stone and more spoil removal.
Soil type: heavy clay is harder to dig and may need a deeper or more carefully drained base than free-draining sandy soil.
Access: if stone and spoil must be barrowed through the house, labour rises sharply.
Disposal: skip or grab hire for the excavated spoil is a real cost, with a minimum charge on small jobs.
Drainage works: a soakaway or extra drainage for an enclosed or boggy garden adds a separate cost.

The base is not the place to save: a thin or poorly compacted base is the most common cause of dips, puddling and weed problems in artificial lawns. Spending properly here protects everything laid on top, and is usually a similar cost to the grass itself.

Drainage and the UK context

In the UK, where rain is frequent, drainage is central to a good base. Artificial grass itself is permeable, but water still has to pass through the pile, through the laying course and stone, and away into the ground or a soakaway. A well-built base is what makes that happen:

Free-draining materials: angular crushed stone and a sharp laying course let water move through rather than pool.
Falls and levels: the surface is built with a slight, even fall so water runs off rather than sitting in dips.
Clay soils: ground that holds water may need a deeper stone layer or a soakaway so the base does not become saturated.
SuDS thinking: replacing a soft, permeable lawn with a built-up surface changes how a garden drains, so a base designed to keep water permeable to the ground beneath is preferable to one that sheds water onto paths or neighbours.

The base is the foundation that decides whether an artificial lawn stays flat, dry underfoot and weed-free for years, or whether it dips, puddles and disappoints. Treated as an investment rather than a place to trim the quote, it is money well spent.

Where base costs vary, and where you can and cannot save

Knowing which parts of the base cost are fixed and which can flex helps you budget sensibly without compromising the foundation. Some elements are genuinely variable, while others should not be skimped on:

Excavation and disposal (variable): if you can do the digging and spoil removal yourself on a small, simple plot, you remove a chunk of labour and possibly some skip cost. On a large or awkward garden, this is hard physical work and usually better left to fitters.
Laying over a sound hard surface (potential saving): where there is already flat, free-draining concrete or paving, the grass can sometimes go over it with minimal preparation, avoiding the excavation and stone sub-base entirely. This is the single biggest legitimate way to cut base cost.
Stone depth (do not skimp): reducing the depth or quality of the sub-base to save money is a false economy — too thin a base settles unevenly and drains poorly. Match the depth to the soil and use rather than the budget.
Membrane and compaction (do not skip): leaving out the weed membrane invites weeds, and under-compacting the stone leaves the lawn prone to dips. Both are cheap relative to the cost of putting the problem right.
Drainage provision (soil-dependent): on free-draining soil little extra is needed; on clay, the extra depth or a soakaway is a necessary cost rather than an optional one.

The pattern is consistent: the savings worth making are in labour you can do yourself, or in avoiding excavation by laying over a sound existing surface. The savings not worth making are in the stone depth, the membrane, the compaction or the drainage — the very things that make the base do its job. A base built properly to suit your soil and how the lawn will be used is the part of the project most likely to determine how long the finished lawn looks good and performs well.

Save on labour, not on the base build: the legitimate ways to cut base cost are doing the digging yourself or laying over a sound hard surface. Cutting stone depth, the membrane, compaction or drainage saves little now and tends to cost more later in dips, weeds and puddles.

Frequently asked questions

Do I really need a stone sub-base?

For grass laid over soil, yes. A compacted crushed-stone sub-base gives the lawn strength, a true surface and drainage, and stops it settling unevenly. Without it the ground moves and the lawn dips, holds water or grows weeds. Grass laid over a sound, flat, free-draining hard surface such as concrete may not need a fresh stone base.

How deep should the base be?

It depends on the soil and use, but a sub-base of crushed stone often in the region of 75 to 100 mm, topped with a finer laying course, is typical for a domestic lawn. Poor-draining clay or heavily used areas may need a deeper build-up. The key is that it is well compacted and free-draining.

Why is the base such a big part of the cost?

Because it is the labour-heavy groundwork — excavating, removing spoil, and spreading and compacting stone — plus the materials themselves. It is often a similar cost to the grass on top, and it is what determines whether the lawn stays flat, drains well and lasts, so it is not worth cutting back on.

Sources & further reading

Figures on this page are typical UK ranges drawn from published cost guides and are intended as guidance, not a quotation.