If you have artificial grass in your garden, then you will need to make sure that the drainage system is up to snuff. The right type of drainage system can affect how well your lawn holds up over time.
This article will discuss what types of systems exist and which one would be best for a given situation.
Does artificial grass need drainage?
First, you need to decide whether or not artificial grass needs drainage at the installation stage.
Answer: Yes, most artificial grass is sewn onto a backing or has drainage holes so water can pass through it.
Artificial grass is often more effective at draining than conventional grass.
There is a misunderstanding when it comes to understanding drainage in synthetic turf products. Just because your turf product says it can drain extremely fast doesn’t mean your sub-base will.
Installers need to understand the type of base materials when installing turf. They often think that they can cover up bad soils with good drainage, but that is not always true.
Eventually, the ground becomes so wet that it can’t absorb any more water. That’s when flooding happens.
If you think your sub-base is not good, we recommend that you dig it up and replace it with a better material.
If the area often floods, then we recommend putting down clean crushed rocks to prevent erosion of the sub-grade materials.
Causes of poor drainage in artificial grass
Sometimes problems are created by mistakes during installation and sometimes they are just a result of natural issues in the earth.
Geologically, problems can be created by soil that retains water easily like clay-based soil and from uneven ground leading to natural puddling as rainwater is directed a specific area such as high groundwater tables underneath the garden.
Artificial grass drainage is a common problem with improperly installed turf, and can be fatal to your lawn or garden.
There are many causes for improper artificial grass installation; one of the most frequent problems being when people install this over an inappropriate surface like concrete without considering proper water run off features.
If your current garden has poor drainage you will need to let the installer know this so they can plan accordingly. Don’t assume that your artificial grass will sort out your drainage issues because if it doesn’t the solution could be expensive!
Issues cause by poor drainage
Poor drainage can cause a host of issues with your artificial grass including a lumpy and uneven base, damp patches of grass throughout, and the need for repairs or even replacement.
Wet ground also give moss, algae and other wildlife a chance to flourish which is a nightmare for anyone who has seen the damage that these can cause.
But of course the worst issue is puddling and wet grass in general. This will make the surface unusable until it is dry
Some problems with your lawn will not be very bad, but others will be big and cost lots of money.
Some problems might even cause you to lose your lawn altogether. To fix this problem, you should start looking for ways to make your garden drain better.
How to prevent poor drainage in artificial grass
As mentioned above, the grass and grit sand base will drain fast, drainage issues are almost always related to the sub base or something else related to installation.
In cases where you have good drainage but the grass is still saturated you may have an much larger issue with the water table.
Don’t lay it on a non permeable base
This may seem obvious but if you lay your artificial grass on a base which will not allow the water to go through it, it will take a long time to dry.
Bases which can be bad for drainage include:
- Paving slabs
Most surfaces which are not the correct grit sand base will be detrimental to drainage however these should only result it mild issues if excess water an still run off the surface.
Water sitting on your artificial grass can also lead to other issues including water freezing over night and damaging the surface.
Installing the correct base
This method is the minimum recommended depth to enhance your drainage. First remove the existing lawn to a depth of 60mm. Next add a sib base consisting of type 1 limestone and a 20 – 30mm layer of coarse sand or granite dust.
The backing of the roll is made with holes that are concealed in between the pile height.
This allows water to pass directly through and into a base below that accepts it.
Artificial lawns dry at a much faster rate than regular grass, since they lack the roots that soak up water.
If you have very bad soil or the area is particularly soft you may need to go down deeper to set a solid base of permeable limestone MOT.
Follow the same method described above but dig out the area to 150mm and fill most of it with type 1 MOT. This will create a similar base to that used when laying paving.
This will greatly enhance your drainage and the amount of water the ground can store before it is saturated.
French ditches are great if you want an effective drainage system that not visible to the eye and can handle large amounts of water.
They are a little tricky to install properly and need a downwards slope of 1 degrees or more to effectively drain the water.
To install artificial grass drainage, first dig out a trench at least 300mm deep and place the perforated pipe inside.
Fill in the space with gravel, then cover that with a permeable landscaping membrane like fabric.
The gravel-filled valley should be covered by a subsurface drainage membrane and can then be covered with soil without compromising the water management.
Laid on a slope and filled with gravel, a French drainage drain helps water escape the surface and seep below or into anther area of the garden.
Soakaway crates should be your secondary option if French drains are not practical. They are a reasonable effective drainage solution but they can fill up easily and cannot be installed within 5m of a property.
Soakaway creates provide 200L of additional drainage capacity under the ground and out of sight.
You can place as many of these as you want as long as it does not destabilise the ground when you are digging the pit.
You will need to dig down to around 800mm to install a soakaway crate so caution should be taken that you do not hit any utilities when digging.
We don’t recommend installing these as a DIY project as there are some risks associated.
Ground elevation is a less popular but still cheap and effective method to improve drainage for your artificial grass. By elevating the artificial grass only 100mm or so above the rest of the garden you can keep it clear of pooling all year round.
Just be warned that water will always flow to the lowest point so if you have just elevated the lowest point water will start moving to the next lowest point.
This solution should not be used against the side of a house or it may end up above the damp course which could then allow moisture into your home.
Artificial grass is a great way to make your home more green and save money on lawn care.
But before you start applying it, be sure to think about what type of drainage system will work best for the space you’re planning to cover with artificial turf.
If you wait until afterwards when considering how much water or rain your new lawn can handle, then chances are that artificial grass installation may end up being unsuccessful and you’ll need to replace all of the fake blades completely.
The good news is that there are many solutions available from French drains, soakaway crates, elevating the ground level higher than where the base will be laid down (to allow runoff), or laying an additional layer of MOT as a deeper base beneath.