What is root barrier installation? 

Root barrier installation involves placing a specialist underground membrane to create an obstruction. Rather than stopping the roots from growing, the barrier re-directs roots away from a foundation’s zone of influence, drainage system or vulnerable areas, while still preserving the tree. A foundation’s zone of influence refers to the area of soil that will potentially be affected by the loads of a building’s foundation.  

The depth and position of the barrier are dependent on the tree, the surrounding ground conditions and type of structure that requires protection. The barrier must be positioned outside of the foundation's 45-degree zone, as installing it within this area can undermine the sub-structure and cause settlement. Essentially, root barriers can provide a targeted solution where tree roots could impact a property’s foundation. Used in combination with other solutions, they can form part of a wider strategy for managing tree-related subsidence risk and protecting nearby structures. 

Why is root barrier installation needed? 

Tree roots branch out in search of water and nutrients in the soil, and if a tree is near a property, its roots can sometimes grow towards it. This can potentially lead to issues such as:  

• Root intrusion around existing structures

• Damage to drains

• Damage to driveways and paving

• Increased risk of subsidence where large trees are growing in shrinkable clay soils

Not all tree roots pose a risk, which means you don’t have to have a barrier installed just because you have a tree close to your property. It depends on the species of tree, the extent of the root growth and the surrounding ground conditions. Our guide will give you a better idea of which trees are more likely to cause subsidence.  

How root barrier installation works 

It depends on the specific requirements of the site, but it usually involves identifying the area that needs protection and deciding where the barrier should be positioned. Once the logistics are sorted, a trench is created so that the barrier can be slotted underground. It’s installed vertically to create a physical boundary between the tree roots and the potentially affected area. Once the barrier is installed, the trench can be re-filled and the surrounding area reinstated. 

What types of root barriers are used? 

There are several types of root barriers. The choice of barrier depends on the type of tree, surrounding ground conditions and risk of potential damage.  

Physical root barriers are typically manufactured from high-density plastic membranes or engineered geotextiles, some of which incorporate copper to help redirect root growth. The barrier is installed underground to block the path of the tree roots. 

Re-designing the landscape can also help discourage tree root growth. This approach can include: 

• Planting trees at a certain distance away from structures

• Choosing a tree species which has a less aggressive root system

• Adding landscaping features such as a retaining wall

Landscaping requires careful planning and is often used alongside other root barriers. 

Does root barrier installation harm the tree? 

If installed properly, a root barrier will not harm the tree. A key benefit of the root barrier is that it provides an alternative to tree removal. The aim of the barrier is to re-direct root growth, not to stop it. That’s why it’s essential these barriers are correctly positioned and installed to minimise unnecessary disturbance to the tree and support its growth. 

What affects the cost of root barrier installation in Ireland? 

Every site is different, which means the cost of root barrier installation can vary. 

As the costs can vary significantly, it’s advisable to seek professional advice from a structural engineer who can give you an estimate based on your property’s requirements. 

Root barrier installation vs tree removal, which costs more? 

Root barrier installation, in some cases, can cost more than removing the tree. At first, it may appear that removing the offending tree is the easiest solution; however, it’s not as straightforward. Firstly, there’s the ecological impact. Trees hold the soil together, so suddenly removing them can increase runoff during heavy rain. Additionally, removing trees in clay-rich soils stops water uptake, causing the soil to swell and potentially damage nearby foundations.

Secondly, you may need permission to remove a tree. Some trees are protected by Tree Preservation Orders (TPOs) and require consent from the relevant local authority before felling, topping or lopping. It’s important to note that most tree felling in Ireland is governed separately by a felling licence system under the Forestry Act 2014. However, trees within 30 metres of a dwelling and small-scale removals are generally exempt, unless a TPO or heritage protection applies. 

In which case, root barriers can offer a more targeted approach than removing a tree. 

How long does installation take? 

The time needed for root barrier installation depends on the size and complexity of the project. A more straightforward installation with good access may be completed faster than projects involving: 

• Extensive excavation

• Difficult ground conditions

• Restricted access

Works may also need to consider the existing landscape, utility networks and other structures close to the problem tree. A site inspection can help provide a better understanding of the potential timescale.   

Protecting properties from invasive tree roots 

Although trees provide urban landscapes with significant environmental and wellbeing benefits, in some cases, their roots can pose a risk to properties and infrastructure if they’re planted too close. A root barrier may offer a targeted approach to manage root growth and protect vulnerable properties without removing the trees.  

If you have any concerns about the tree root growth affecting your property, it’s advisable to seek professional advice. Mainmark specialises in the installation of a copper geotextile tree root barrier. The copper is embedded in a geotextile membrane that forms the barrier. Copper ions released from the barrier inhibit root tip growth when roots encounter the membrane, encouraging roots to redirect and branch away from the protected area without harming the tree. Speak to us today to learn more.