Installing artificial grass in your garden is a relatively simple process and will make a great asset for years to come. However, if you fail to install your synthetic turf properly, the end result will be far from desirable.

 What goes under artificial grass is arguably one of the most important steps because it will drastically affect the longevity and finish of your lawn. This extends further than your artificial turf underlay!

Artificial grass sub-base is an essential step in theinstallation process. It is also the one, however, that is little known to the general public. This is particularly true of those laying their own lawn. The whole process can be rendered more difficult by false advice found on the internet. To install your artificial grass yourself or to know more about it, learning about the sub-base from a reliable provider is fundamental.

We’ve put together this handy guide to explain what a sub-base is and why you need it. It aims to equip you with the knowledge to move forward with your artificial grass project confidently. With over 20 years of experience in installing artificial grass, we believe we have developed the best method to set up the perfect artificial lawn every time.

 What is Artificial Grass Sub-Base?

Laying a synthetic lawn is not quite as simple as placing it over the top of your existing turf. It requires a host of preparations. So, what do you put under artificial grass? After you have removed your turf (or whatever is currently covering the space) and then roughly levelled out the surface, you want the grass to sit on top of a sub-base. A sub-base is a layer of aggregates that is installed beneath your artificial grass to create a level, stable, and structured surface for the grass to sit on top of.

 Why Install a Sub-Base?

If you don’t install a sub-base underneath your synthetic grass, your lawn will have much less stability and strength, which could cause it to sink under the weight of people or furniture placed on top of it. The installation of an artificial grass sub-base helps drain your lawn, which is essential to preserve its life and prevent the pooling of rainwater.

 Types of Artificial Grass Sub-Base

There are a few sub-base options, the most common being crushed granite stone. This is sometimes referred to as Grano dust or 4-6mm dust.  You can also use limestone instead of granite and for dog lawns you can use a small diameter aggregate without fines for maximum drainage. At Artificial Lawn Company we have our own special crushed granite mix made for us which is 4-6mm crushed granite with a small amount of dust (fines). Type 1 is also quite commonly used underneath the granite as an extra measure to promote drainage and strength to the subbase itself.

 Do You Need a Sub-Base for Artificial Grass?

Our special blend is different from most as it consists of more stone than dust, giving it excellent drainage, which is important for pet owners as the dust does hinder the drainage slightly. This is one of the reasons you should use a sub-base and choose us for your artificial grass installation. Our artificial lawn sub-base has the best quality and finish, making it last for at least 12-15 years.

Artificial Grass Sub-Base Material – What Underlay Should Be Used?

There are different types of sub-base for artificial lawns. However, choosing the right composition depends on the surface and how much levelling out the surface needs.

At Artificial Lawn Company, we prefer to use crushed granite because it boasts the maximum drainage possible and compacts for a firm and level finish. However, if the surface did not have real grass before, you may need to use MOT Type 1 because it can be compacted into a harder surface to prevent sinkage. This is particularly important when raising the levels of the garden area. Though crushed granite also forms a hard surface, it will not be as strong as type 1 when installed to a depth greater than 50mm.This is because MOT type 1 consists or larger stones as well as the fines for a much stronger compaction.

 Crushed granite sub-base can be used:

• Where natural turf, paving or shingle was present before.
• On areas that do not need too much levelling and have small lumps and bumps only.
• On areas that require a build-up or have a depth of 25mm-50mm.

MOT Type 1 sub-base is used:

• On areas with a depth of more than 50mm to fill or raise.
• In newly built gardens that have not had adequate time for consolidation and compaction of the soil (this can take many years).
• When infilling an old fishpond (it helps reduce the risk of sinkage as it firmly consolidates the pond area).
• When covering a flowerbed or an area where a large tree or bush has been removed (roots can take a while to decay and, as they do so, the soil can shift and soften, leading to sinking. Type 1 will help mitigate these effects).

If MOT Type 1 is used, we will always add a 25mm layer of crushed granite on top for drainage and levelling purposes. In cases where lots of levelling is required, it is common to use type 1 in the dips greater than 50mm and then crushed granite stone for the rest of the area. For all sub-base options, the key to a great and long-lasting finish is thorough compaction using a wacker plate. When increasing the levels by large amounts, it is best to build up in layers of ~50-100mm and compact as you go. A ground separation membrane should also be used for large buildup to keep the subbase separate from the ground underneath.

How to Install Sub-Base for Artificial Grass?

Once you have removed the existing covering (natural grass, paving, shingle, etc), it is best to level off the area you would like to cover loosely. You can then add your crushed granite stone subbase to a depth of 25-50mm and compact it thoroughly. A good quality weed membrane should then be added on top to prevent weeds from coming through and penetrating your artificial lawn. If needed, you can add an underlay shock pad and, finally, your synthetic lawn.

Talk to Us

The process of installing artificial lawns and artificial grass sub-base can be complicated. Feel free to contact us with any questions about synthetic grass, the types that are available and the installation process. We will be happy to help you!

The information detailed above will be useful to complete a DIY project or any landscaping or gardening job. Good luck with your upcoming project!

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