Three reasons why your dream lawn could turn into a perfect nightmare…
It’s an unfortunately common scenario – a once perfect looking artificial lawn is now lumpy and bumpy – better resembling a crazy-golf course than the lawn you always dreamed of.
Whether it’s six, eight, twelve months or more since your initial installation there are a few common reasons why lumpy, bumpy artificial grass happens and they all come down to bad groundwork. Always employ a professional and you will avoid these pitfalls. These two points are the most common reasons for lumpy bumpy artificial grass:
1: Inadequate turf and top-soil removal from the underlying lawn area. One of the main objectives when removing the existing lawn area is to find a ground level that is sufficiently firm and well-draining upon which to build a base for your artificial turf. Grass and topsoil form a spongy ground layer and this is not adequate for the uniform support of synthetic turf. There are no ‘one-size-fits-all’ methods to this and often it may mean digging deeper in some areas than others. It may even mean digging deep holes in some areas until you find that level. It is not sufficient in most circumstances just to skim the very top layer of grass and topsoil. 100mm depth should be achieved as a very minimum .
Also related to this same point – if artificial grass is laid over real grass, twigs, plants or other similar organic material the grass will become uneven as the organic material decomposes at different rates. It is essential to remove all of this type of organic material during the installation process.
2: Inadequate base construction. Base construction can vary from contractor to contractor but there are a few key characteristics you need from a good artificial grass base:
- to provide a firm but forgiving base
- to drain freely
- to be free from organic material that can decompose and encourage habitation by living organisms
This is why we recommend the following as standard:
- a ground-stabilising geotextile to separate the existing stripped back lawn area (soil) and your new base. Without this geotextile a base will slowly compact into the soil which over time will result in the lawn becoming lumpy and bumpy. This geotextile will also act as a weed barrier at the bottom of your base rather than at the top which is where weed barriers are more commonly (and less effectively) used.
- a sub-base constructed from compacted quarried stone aggregate (don’t buy recycled it can contain contaminates which may decompose and other more hazardous impurities like nails, glass or wire.) Ideally we recommend this to be 100mm deep or more made up of 75mm compact DTp1 and 25mm of quarried 4mm to dust as a surface layer or similar.
- a final base constructed from compacted crushed quarried stone aggregate such as 4mm to dust. We recommend carboniferous limestone for this. This sub-base and base should be built up in layers compacting with a wacker plate or vibrating roller every 75mm.
This base construction will provide everything you need for a lawn that drains well, never loses shape and is forgiving enough to absorb the impact of a fall.
A note about sand. Many installers recommend sand as a final base layer for artificial grass. We recommend a 4mm(+) to dust (sometimes known as stone dust) over sand for a number of reasons:
- stone dust compacts better. No matter how many times you run a wacker plate over sand it won’t lock together to provide a sufficiently firm surface. Stone dust will.
- sand holds more moisture. This means it will also hold more bacteria (especially relevant if you have pets) and it will also affect the lawns ability to drain.
- sand provides a better rootzone for seeds germinating in the grass thatch with roots finding their way through drainage holes.
3: Plant bulbs. This goes back to the first point but it’s such a potentially big issue (and a common one) that we thought it was worth mentioning on its own. Bulbs are stores of energy waiting to burst out of the ground at the first opportune moment. Bulbs don’t need direct sunlight to grow, just the right combination of heat and moisture.
Bulbs can create monstrously alien looking formations underneath artificial grass. Artificial grass can actually even aid and speed up the growth of bulbs by providing ground insulation!
The key thing to remember here is to make sure the ground where you are going to install your artificial lawn is free from plant bulbs. This is especially relevant if the new artificial lawn area is going to go over previous planting areas such as flower beds.