Avoid root damage by using root barriers
Posted on Jan 4, 2017
Roots of trees and shrubs cause damage to gardens, public spaces and roads. Find out how to counteract this with root barriers from S-Polytec.
The roots of shrubs or trees spreading underground can cause enormous visible, but also invisible damage, which can result in high costs.
With a properly installed root barrier, however, damage to pavements or utility lines laid underground can be effectively avoided.
With a properly installed root barrier, however, damage to pavements, roads or underground utility lines, as well as the uncontrollable spread of plants, can be effectively and easily avoided.
The purpose of erecting a root barrier is to prevent the roots of plants from spreading uncontrollably and thus causing damage that is not always obvious at first glance. An unwanted spreading and proliferation of shrubs and ground covers can also be prevented by properly installed root barriers.
Everyone who enjoys a bamboo shrub as an ornamental plant in the home garden is certainly familiar with the problem that it spreads after a short time with long roots running just below the surface, causing new bamboo shoots to sprout from the soil everywhere within a radius of several metres.
Many cities and municipalities have long since discovered root protection and prevent damage caused by root growth. This is an investment that pays off, because it reduces the repair costs of pavements and streets caused by root damage enormously.
What should you look for in a root barrier?
There are several factors to consider when installing a root barrier. The board used must be suitable for permanent outdoor use; after all, it is uneconomical if the root barrier has to be renewed at regular intervals. Wooden boards, for example, are not suitable for use as root barriers because the damp soil is very hard on the wood, so that it rots over time and can no longer fulfil its purpose. Most metals are also not suitable for permanent use underground without appropriate corrosion protection. Stainless steel would be a possible alternative, but here the price and performance are absolutely disproportionate. With the right plastic, on the other hand, you make a good choice when it comes to erecting a root barrier that, once correctly installed, requires no further work or maintenance.
In addition to choosing the right metal, you can also choose a plastic that is resistant to corrosion.
In addition to choosing the right material, you also need to consider the dimensions and thickness of the panel used as a root barrier. Here, among other things, the root system of the relevant plants should also be taken into account. Depending on the size and type of the plant, the spread of the roots can already vary greatly.
Which plastics are suitable for the construction of root barriers?
When choosing a suitable plastic material for the construction of a root barrier, care should be taken to ensure that it is durable and long-lasting. Furthermore, the material should be free of plasticisers and toxins that could decompose and enter the soil.
Polyethylene - PE for short - is a very chemically resistant plastic that does its job reliably, even after many years underground. Polyethylene is impact resistant and is considered physiologically harmless, which means that polyethylene is food safe and therefore does not leach hazardous substances into the soil. Due to its high impact strength, PE can withstand even the greatest loads.
This makes polyethylene the best choice when it comes to plastic root barriers.
What thickness should you use for a root barrier?
To prevent the root spread of grasses, ground covers and light shrubs, such as bamboo, a low thickness of about 3mm-4mm and a height of about 450mm-500mm is quite sufficient. Only in rare cases do the roots of native bamboo grow beyond this depth.
However, there are also shrub plants whose roots are already somewhat stronger, as is the case with hydrangeas or magnolias. To put it simply, this applies to all shrubs with branches that become woody over time. Here, the thickness should be chosen a little higher depending on the size of the shrub, so that you should choose plastic sheets made of polyethylene with a thickness of approx. 4mm-10mm for your root barriers. The necessary height of the root barrier also depends on the type of shrub. However, you should be on the safe side with a height of 500mm - 750mm.
For trees, which usually form quite strong, powerful roots and are therefore most likely to cause damage, quite high thicknesses are required. Slab thicknesses of 10mm-15mm are advisable here. Depths vary from one to two metres, depending on the type of tree.
If you are not sure what kind of shrub it is, or how wide and deep the root system of this plant spreads, a garden and landscape contractor can certainly tell you more. Also, when planting new grasses, or other plants, you can find out about this at the time of purchase.
Generally, it must be mentioned at this point that roots once deflected downwards do not grow upwards.
How to erect a root barrier?
This is how you prevent the uncontrolled spread of shrubs and grasses.
The pit needed for planting is first excavated. The walls of the pit must then be lined with the root protection. For thinner thicknesses, such as 3mm, the material can simply be laid vertically on the earth wall with a small overlap. An overlap of 10cm-20cm is quite sufficient. However, when placing the panels, make sure that they are inserted vertically or that the top slopes towards the plant. A slope towards the edge of the excavation, on the other hand, can lead to the roots being diverted upwards and the root barrier would then fail in its purpose.
The shrubs are then planted and the pit is filled with topsoil. Make sure that the overlap of the root protection is not pulled apart too much. An overlap of the plastic sheets of at least 10cm should be ensured.
This way you protect pavements, roads or utility lines from tree roots.
When lining root barriers thicker than 5mm, things get more complicated. Due to the thickness, the panels can no longer be rolled along the wall but only buried as one straight panel. In such cases, the entire area is not usually covered with root protection. It is usually sufficient if only the area to be protected is lined, such as lateral root growth towards a pavement or road. the same applies to supply lines, pipes or drainage running next to the tree. Here, it is sufficient to install the root protection panel on the affected sides. This keeps the roots out of the area to be protected and allows them to spread in the remaining directions. In this case, please ensure that the plates are placed vertically or with a slight slope in the direction of the tree so that the roots are not diverted upwards.
As with the shrubs, the excavation is filled with topsoil after the root protection plate has been placed so that the root barrier is no longer visible.
Configure root barriers online at S-Polytec
Buy your root barriers conveniently online in the right size.
In our shop, we offer the right polyethylene root protection sheets in different thicknesses cut to size, so you can freely configure any size to fit your plants.