Various terms are used for the artificial turf base, such as underlay, foundation, groundwork, and the English term “sub-base” is also commonly used. In principle, they all refer to the same thing. For the best results, artificial turf should be laid on a base that is stable, load-bearing, level, and sufficiently water-permeable. The construction can be strongly compared to the base of decorative paving. There are, of course, different possibilities, and there isn’t a one-size-fits-all “best” option; it also depends on the future use and the current condition of the soil. Below, we have provided detailed descriptions of the most common bases. (If there is an existing lawn, the current artificial turf must, of course, be excavated and removed first.)
Laying artificial grass on sand
In many cases, for a garden, a sandbed of yellow sharp sand (paving sand or paver sand) ranging from 10 to 15 centimeters is sufficient. The thickness depends on the local soil conditions. For instance, on poorly water-permeable clay soil, a slightly thicker layer may be required than on well-draining sandy soil.
The outcome is determined by properly allowing the sand to settle, expelling all air from the sandbed, for example, by watering, and then compacting and leveling it well. Subsequently, you can install the artificial turf on this sandbed. However, a sand layer will naturally subside earlier than a more robust foundation, such as crushed rock or sand-cement (see the following paragraphs).
A slightly more expensive alternative is grit sand. It is not technically sand but gravel that has been finely crushed (broken) into sand. Due to its angular shapes, it provides a sturdier base than paving sand. It is advisable to avoid using fill sand, as it is often not permeable enough to water.
Paved surface artificial grass
A hardened subbase is a foundation capable of withstanding heavier loads, achieved through the use of crushed rubble, also known as aggregate or recycled concrete aggregate (repac). This type of foundation is also employed beneath driveways and roads. In this case, the subbase consists of two layers: the bottom layer of crushed rubble and a thin finishing layer of sand for leveling. The thickness of the rubble foundation varies between 8 and 15 cm, while the finishing layer ranges from 2 to 4 centimeters. This subbase for artificial turf is applicable when it will be subjected to heavy loads.
A similar construction can be created using lava (lava granules). Lava has the advantage of being lightweight, which can be beneficial for installing artificial turf on a rooftop or in a rooftop garden, for example. Another advantage of lava is that it can often be ordered in a finer grade than crushed rubble (such as 0-8). This allows the foundation to be built and finished in a single layer. If you lack experience in creating this type of foundation, we recommend hiring a specialist.
Additionally, foundation materials such as boiler sand (derived from power plants) and steagran (from blast furnaces) are available. These are materials commonly used by contractors and specialists. The functional value is generally similar. For more information, it is advisable to consult the supplier.
Artificial grass on sand cement / stabilized
A commonly used foundation for laying artificial turf, particularly in Belgium, is sand-cement or stabilisé. In this artificial turf subbase, sand is mixed with cement. The ratio of sand to cement is crucial. If too much cement is used, the stabilisé becomes less permeable to water. The application and leveling of stabilisé are also challenging tasks. Creating a sand-cement foundation is, therefore, specialized work. When done properly, it is an excellent foundation as it does not subside and can withstand heavy loads.