If tree roots are threatening your property’s infrastructure but you want to keep the tree, a root barrier may be the solution. Root barriers are physical or chemical barriers installed underground to redirect root growth away from foundations, pipes, driveways, and other vulnerable structures.
How Root Barriers Work
Root barriers create an underground wall that roots cannot penetrate or grow through. When roots encounter the barrier, they are deflected downward or along the barrier’s face, redirecting their growth away from the area you want to protect. This allows you to retain a valued tree while preventing ongoing damage.
Types of Root Barriers
Solid Physical Barriers
High-density polyethylene (HDPE) panels are the most common type. These rigid plastic sheets, typically 2 to 4 millimetres thick, are installed vertically in a trench to a depth of 600 to 900 millimetres. They are durable, non-toxic, and effective against most root systems.
Fabric Barriers
Geotextile fabric barriers use copper-impregnated or herbicide-treated fabric that chemically inhibits root growth on contact. These are more flexible to install around curves and existing infrastructure but may need replacement over time as the treatment degrades.
Concrete and Masonry Barriers
In some cases, a concrete footing or masonry wall serves as a root barrier. While effective, these are more expensive to install and less commonly used purely for root management.
Installation Process
- An arborist assesses which roots need to be managed and where the barrier should go
- A trench is excavated to the required depth, typically 600mm to 900mm
- Any existing roots crossing the trench line are cleanly pruned by the arborist
- The barrier material is installed vertically with minimal gaps at joints
- The top edge of the barrier is positioned slightly above ground level to prevent roots growing over it
- The trench is backfilled and the surface restored
Cost of Root Barriers
Root barrier installation typically costs $50 to $150 per linear metre, including materials, excavation, and installation. A typical residential installation protecting a house foundation might run 10 to 20 metres, putting the total cost at $500 to $3,000. The cost is often less than tree removal and can be a cost-effective alternative when council will not permit removal.
When Root Barriers Are Appropriate
Root barriers work best as a preventive measure or when root damage is still in its early stages. If roots have already caused significant structural damage, root removal or tree removal may be the more practical solution. For advice on dealing with roots that have already entered pipes, see our guide on tree roots in pipes.
Limitations to Be Aware Of
Root barriers are not a permanent set-and-forget solution. They need periodic inspection to ensure roots have not found a way around or over the barrier. They also do not address existing damage, which will need separate repair. For more on the complete range of root management options, see our tree root removal guide.
Want to protect your property from root damage without losing your trees? We connect you with qualified arborists who specialise in root management solutions. Find a root barrier specialist near you for professional assessment and obligation-free quotes.