A synthetic lawn only performs as well as the surface beneath it. If you are asking, “what base for artificial grass?”, the short answer is a stable, well-compacted, free-draining foundation suited to your site. Get this stage right and your turf will sit smooth, drain properly and keep its clean appearance through years of use.
The right base is not simply a layer of sand tipped onto the ground. Soil type, existing levels, drainage, traffic and the purpose of the area all affect the specification. A front lawn, a pet run, a school play space and a putting green may all use artificial turf, but they do not necessarily need the same foundation.
Why the base matters under artificial grass
Artificial grass does not need soil to grow, but it does need support. A properly prepared base prevents soft patches, ripples, visible joins and water pooling. It also helps the lawn cope with foot traffic, outdoor furniture, pets and the changing conditions common across Melbourne properties.
Without adequate excavation and compaction, the ground can settle after installation. That can leave low spots where water gathers or create an uneven surface that is noticeable underfoot. Rectifying a failed base often means lifting the turf and starting again, which is why professional preparation is a worthwhile part of the project.
A good base has three jobs: it creates a firm platform, allows water to move away from the surface and provides a fine, even bed for the turf. Each layer needs to be installed with the finished level in mind, particularly around paving, garden edging, drains and door thresholds.
What base for artificial grass is right for your site?
For most residential landscape installations, the preferred system is a compacted crushed-rock sub-base topped with a finer levelling layer. This gives artificial grass a solid footing while allowing water to pass through the turf backing and into the ground below.
The exact depth depends on site conditions. A firm, naturally well-draining yard may need less excavation than a clay-heavy area, a section with poor drainage or a space that will receive regular traffic. As a general guide, a residential lawn often requires excavation of around 70 to 100 mm, allowing for the turf, crushed rock and fine bedding layer. Heavily used areas may need a deeper and more engineered base.
The goal is not to apply one depth to every project. It is to build sufficient support for the ground conditions and intended use while maintaining correct finished heights. Turf should meet adjacent surfaces neatly, not sit too high against pavers or create a lip at a footpath.
The compacted crushed-rock sub-base
A crushed-rock layer forms the structural part of the installation. It is spread in controlled layers, lightly moistened where appropriate and compacted using suitable equipment. This process locks the material together and reduces the risk of future movement.
For many domestic applications, crushed rock around 20 mm in size is used as the main sub-base. It provides strength without creating large voids that can make levelling difficult. The material should be installed evenly, rather than being piled in one thick layer and compacted only on the surface.
Compaction is where many DIY installations fall short. Rock that looks flat can still be loose beneath the top crust. Proper compaction creates a dense, stable foundation and is particularly important near edges, corners and areas that will carry furniture, bins or regular foot traffic.
The fine levelling layer
Over the compacted rock sits a fine layer used to achieve a smooth final grade. Depending on the system and site, this may be crusher dust, decomposed granite or another fine aggregate specified for artificial turf installation. It is screeded carefully to remove high and low points before the grass is laid.
This is not a substitute for a structural base. Fine material alone can shift or wash away, especially on sloping ground or in wet conditions. Its role is precision: creating a clean, even surface that supports the turf backing and gives the lawn a natural finish.
Drainage should be planned before the turf is laid
Most quality artificial grass has a perforated backing that lets water drain through. However, drainage still depends on what happens below the turf. If water has nowhere to go, even the best turf will not solve the problem.
The prepared base should generally fall gently away from buildings and towards an appropriate drainage point. A subtle gradient is enough. The aim is to move surface water without making the lawn feel sloped or look uneven.
Clay soils deserve particular attention. They are common in many parts of Melbourne and can hold water beneath the base. In these areas, additional drainage measures may be required, such as agricultural drains, drainage gravel or a revised base design. The right solution depends on how the site behaves after rain, where existing stormwater runs and whether there are low points in the yard.
Geotextile fabric can also be useful between soil and the base material. It helps separate the sub-base from the underlying ground, reducing the chance of fine soil migrating into the rock over time. It is not required on every job, but it can be a sensible addition on soft, unstable or clay-based sites.
Preparing different existing surfaces
The starting surface changes the installation method. On a natural soil yard, the process usually begins with removing existing lawn, roots, loose soil and organic material. Any remaining vegetation can decay and create uneven areas, so preparation needs to be thorough.
On an established soil base, edging is installed before the final layers are completed. Strong edging holds the artificial grass securely and keeps the base contained, particularly along garden beds and curved lawn shapes. It also makes it possible to achieve tidy, durable borders without relying on visible fixings alone.
Concrete, paving and other hard surfaces can sometimes be used as a base for artificial grass, provided they are sound and drain correctly. Turf can be installed over concrete for balconies, courtyards, display areas or recreation spaces, but the surface must have a suitable fall and functioning drainage. Water trapped between turf and concrete can lead to odour, staining or mould growth.
Hard surfaces may also need a shock pad or drainage layer, depending on the application. This is especially relevant for children’s play zones and some sports installations, where comfort and impact performance matter as much as appearance.
Base requirements for pets, play and sport
A standard residential base works well for many lawns, but specialised uses need closer planning. Pet areas should drain efficiently and be designed for easy cleaning. In some cases, odour-control infill and enhanced drainage are more valuable than simply increasing the amount of base material.
For children’s play spaces, a shock-absorbing underlay may be required to help reduce impact risk. The need for this depends on equipment height, use patterns and the relevant safety requirements. It should be considered as part of the whole system, not added as an afterthought.
Sports surfaces require the most specific base design. A tennis court, cricket wicket, putting green or multi-use recreation area needs accurate levels, reliable drainage and performance characteristics matched to the sport. A putting green may include shaped contours and a compacted base designed for true ball roll, while court surfaces may require engineered layers to manage load, rebound and water movement.
Common base mistakes to avoid
The most expensive mistakes are usually hidden beneath the turf. Installing over unprepared soil, skipping compaction or using loose sand as the only base can lead to settling and an uneven finish. Covering an existing drainage issue instead of addressing it first will usually result in puddles returning after the first substantial rain.
It is also a mistake to make the finished lawn perfectly level when the surrounding site needs water directed away from a building. Level-looking and level are not the same thing. A properly graded lawn can appear flat while still supporting drainage.
Finally, avoid treating edging as a cosmetic detail. Secure edges help maintain the shape of the lawn, support the base and keep the perimeter looking neat over time. They are part of a professional installation, not an optional extra.
A base built for a lasting finish
Choosing the right base for artificial grass is about more than selecting crushed rock or a fine aggregate. It is about assessing the site, controlling water, creating stable levels and matching the system to how the space will be used. When those details are handled properly, the finished surface looks clean from day one and remains comfortable, durable and low-maintenance long after installation.
If your yard has poor drainage, difficult access, uneven levels or a specialised use in mind, have the base assessed before selecting turf. A well-prepared foundation gives premium artificial grass the performance and finish it was designed to deliver.