If you have ever seen artificial grass that looks flat, rippled or waterlogged after a bit of rain, the problem usually is not the grass itself. It is what goes under artificial grass that determines how well the surface drains, how firm it feels underfoot, and whether it still looks right a few years down the line.
A good artificial lawn is built from the ground up. The visible surface matters, of course, but the layers underneath do most of the hard work. They provide support, help with drainage and stop the lawn from shifting or sinking. Exactly what sits beneath the grass depends on the area, the soil conditions and how the space will be used, but there are a few core components that appear on most well-installed projects.
What goes under artificial grass in most gardens?
In a typical domestic installation, the build-up under artificial grass includes a prepared ground level, a compacted sub-base, a laying course, and the grass itself, often finished with kiln-dried sand. In some cases, a weed membrane or shock pad may also be included.
That sounds simple enough on paper, but each layer has a job to do. Miss one, use the wrong material, or install it poorly, and the lawn can start to move, hold water or develop low spots.
The first thing to understand is that artificial grass should not usually be laid straight onto bare soil. Soil shifts with weather and foot traffic. It can become soft in winter, hard in summer, and uneven throughout the year. That movement transfers straight to the surface.
The sub-base is the most important layer
When people ask what goes under artificial grass, the most important answer is the sub-base. This is the compacted foundation that supports the whole installation.
For most gardens, installers use a permeable aggregate sub-base, often a crushed stone such as MOT Type 1 or granite dust depending on the ground conditions and intended finish. The right choice depends on the site. A heavier stone base can give excellent stability, while a finer finish layer helps create a smooth, even surface for the grass.
What matters most is not only the material, but how it is installed. The sub-base needs to be laid to the correct depth, spread evenly and compacted properly in layers. If that process is rushed, the ground may settle later, leaving dips and an uneven finish.
Depth varies from project to project. A small ornamental lawn in a sheltered garden may not need the same build-up as a family garden with regular use, pets or poor drainage. Existing soil conditions make a difference too. Clay-heavy ground often needs more careful preparation because water drains through it slowly.
Why drainage needs thinking about early
One of the main reasons artificial grass performs well in British gardens is that it can drain quickly when installed properly. But that only happens if the base underneath allows water to move through.
Artificial grass itself is usually perforated, so rainwater passes through the backing. From there, it needs to move into a free-draining base and away into the ground below or towards suitable drainage points. If the base is too dense, badly compacted or laid flat without thought for water movement, puddling can become a problem.
This is why proper site assessment matters. A shaded back garden in Lancashire with heavy clay soil may need a different approach from a lighter, sandier site elsewhere in the North West. There is no single build-up that suits every property.
The laying course creates the finish
Above the main sub-base, there is often a finer laying course. This helps smooth out the surface before the grass is fitted.
Depending on the specification, this may be a layer of granite dust or a similar fine aggregate. Its job is to provide a neat, level platform so the finished lawn looks natural rather than bumpy. It also helps the installer achieve accurate falls and edges.
This is one of those stages where workmanship really shows. Small imperfections in the base can become far more noticeable once the grass is down, especially in strong sunlight or when looking across the lawn from a patio or kitchen window.
Does a weed membrane go under artificial grass?
Sometimes yes, but it depends on the installation method and the site.
A weed membrane is not there to make up for poor ground preparation. Its role is to help suppress weed growth from below, reducing the chance of unwanted growth coming up through joins or edges. On a properly excavated and prepared area, it can be a useful additional layer, but it is not the structural foundation of the lawn.
It is also worth being realistic here. No membrane can guarantee that weeds will never appear. Airborne seeds can still settle on the surface over time, particularly around borders and edges. That is a maintenance issue rather than a failure of the base.
What goes under artificial grass for play areas?
If the lawn is being used by children or in an area where extra cushioning is needed, a shock pad may be installed beneath the grass.
Shock pads are designed to add softness underfoot and improve impact absorption. They are not necessary for every garden, and some homeowners prefer a firmer feel for general use. For children’s play spaces, though, they can make the area more comfortable and better suited to active use.
As with any extra layer, there is a trade-off. A shock pad changes the feel of the lawn and can slightly affect the finished height. It needs to be factored into the build-up from the outset rather than added as an afterthought.
What goes under artificial grass for pets?
Pet-friendly artificial grass still relies on the same core principles – solid ground preparation, drainage and a stable base.
The difference is that drainage becomes even more important. If the area is used regularly by dogs, the base needs to allow water and wash-downs to pass through effectively. In some cases, the build-up may be adjusted to improve permeability or odour control, but the foundation still needs to be firm and properly compacted.
This is where shortcuts tend to show up quickly. If the base holds moisture, smells can linger and the surface may become less pleasant to use.
Can artificial grass be laid on concrete?
Yes, in some situations, artificial grass can be installed over existing concrete or paving, provided the surface is sound, drains properly and is prepared correctly.
That said, concrete is not the same as a purpose-built sub-base. If there are cracks, poor falls or drainage issues, those need dealing with first. The finished lawn may also feel firmer than one installed over a fully prepared aggregate base. Sometimes that is acceptable. Sometimes it is not ideal, particularly in family gardens where comfort matters.
The key point is that the answer to what goes under artificial grass is not always the same material on every site. Existing surfaces, intended use and drainage all shape the right approach.
Why edging and perimeter support matter too
The layers beneath the middle of the lawn get most of the attention, but the edges are just as important.
Artificial grass needs secure perimeter support so it can be fixed neatly and held in shape over time. Without that, edges can lift or look untidy, especially around curves, patios and borders. Timber, composite or other suitable edging systems may be used depending on the design.
This tends to be one of the details homeowners notice only when it goes wrong. A lawn can have a decent central area but still look poorly finished if the edges are weak or irregular.
The wrong base causes most long-term problems
When an artificial lawn fails early, the cause is often underneath. It may not be enough excavation, poor compaction, the wrong aggregate, weak edging or inadequate drainage planning.
You might not see those issues on the day the grass goes down. The surface can look tidy at first. Problems usually appear later, after rainfall, regular foot traffic and a change of seasons. Low spots, ripples and movement rarely come from nowhere.
That is why experienced installers spend so much time on the unseen part of the job. Ground preparation is rarely the most exciting stage, but it is the stage that gives the lawn its lifespan.
A well-built base should suit the garden, not a template
The best answer to what goes under artificial grass is this: a properly designed foundation for that specific garden.
Some spaces need more excavation. Some need better drainage planning. Some benefit from a shock pad, while others are better with a firmer finish. A front garden used mainly for appearance does not need exactly the same construction as a back garden used daily by children and dogs.
That is why a professional survey is so useful. It allows the installer to assess soil type, levels, drainage, access and intended use before deciding on the right build-up. At Elite Artificial Lawns, that site-specific approach is what helps create lawns that not only look right on completion but continue to perform properly over time.
If you are considering artificial grass, pay as much attention to the base as the surface. The grass is what you see, but the layers underneath are what make it feel right, drain properly and stay looking smart year after year.