Lifted kerbs, cracked paving and uneven footpaths are often blamed on tree roots. It’s one of the biggest concerns surrounding urban tree planting, particularly in streets, public spaces and hard landscapes where trees sit alongside roads, utilities and buildings.
In reality, tree roots are rarely the problem. Pavement damage is usually the result of poor below-ground design. When trees are provided with sufficient soil, oxygen and space to establish, roots are far less likely to create conflicts with surrounding infrastructure.
Why Do Tree Roots Damage Paved Surfaces?
Tree roots naturally grow towards the air, water and nutrients they need to survive.
In some tree planting systems, however, the surrounding soil ends up heavily compacted to support roads and pavements, leaving very little suitable rooting space.
Without adequate soil volume, roots follow the path of least resistance, often growing immediately beneath paved surfaces. As they increase in size, they can lift and displace the pavement above, creating cracked paving, uneven footways and displaced kerbs. This is known as root heave.
Root heave is rarely caused by aggressive root growth. More often, it is a response to inadequate growing conditions below ground.
How Can Pavement Cracking and Displacement Be Prevented?
The most effective way to reduce root heave is to provide sufficient uncompacted soil volume from the outset.
Structural soil cell systems make this possible by supporting the pavement independently while creating large volumes of healthy rooting space beneath hard landscapes.
GreenBlue Urban’s RootSpace system maximises available soil volume while providing the structural support required for the pavement above. This allows both the tree and the surrounding infrastructure to be considered as part of the same integrated design.
Can Tree Roots Damage Buildings?
Tree roots growing near buildings, drainage infrastructure and underground utilities are another common concern.
The solution is not to avoid planting trees in constrained urban environments, but to design the rooting environment appropriately.
Tree species, soil conditions, available rooting volume, surrounding infrastructure and anticipated mature size should all be considered during the design process. When combined with appropriate root management measures, trees and infrastructure can successfully coexist.
Installation is Part of Engineering Performance
Too often, installation is treated as a separate consideration from engineering design.
In reality, the two are closely linked.
A structural tree pit system should perform when the finished surface is complete, and it should also provide stability and reliability throughout the build process itself.
This means maintaining alignment during filling operations, supporting safe access for installers, minimising unnecessary construction stages and reducing the potential for movement before the structure is fully assembled.
When installation is considered as part of the overall engineering performance of a system, projects can benefit from greater consistency, reduced risk and improved construction efficiency.
Just as importantly, the conditions required for long-term tree establishment are protected from day one.
Building Stability into the Construction Process
This is one of the principles that has guided the development of RootSpace.
Rather than relying on temporary stabilisation components during installation, the system is designed to achieve structural stability early in the construction sequence. Perimeter lids are installed at an early stage to secure the structure and maintain alignment while soil is progressively placed and compacted.
This approach helps create a stable working environment during installation, allowing contractors to move freely within the structure while maintaining consistent geometry throughout the build process.
The result is a simpler installation sequence with fewer components, reduced material handling and less reliance on temporary measures that require additional storage, management and removal on site.
Most importantly, it helps ensure that the soil volume specified at design stage remains protected throughout construction.
FAQ's
Tree roots can contribute to pavement damage when they are forced to grow immediately beneath paved surfaces due to inadequate rooting space. In most cases, the underlying cause is insufficient soil volume rather than the tree itself.
Root heave occurs when roots grow beneath paved surfaces and gradually lift or displace them. This is typically caused by restricted below-ground growing conditions that force roots towards the surface.
Tree roots can interact with nearby buildings and infrastructure, but this depends on site conditions, tree species, soil type and the design of the rooting environment. Proper tree pit design and root management can significantly reduce the risk of conflict.
Soil cell systems support the pavement independently while creating large volumes of uncompacted soil beneath the surface. This allows roots to establish within the intended rooting zone rather than directly beneath the pavement.
The required soil volume depends on the tree species, its expected mature size and the site conditions. Providing adequate uncompacted soil is one of the most important factors in supporting long-term tree health and reducing conflicts with surrounding infrastructure.
Root barriers and root directors are designed to guide root growth away from sensitive infrastructure such as pavements, utilities and building foundations while allowing healthy root development within the intended rooting zone.
Tree roots may exploit defects or joints in underground infrastructure if favourable conditions exist. Good tree pit design, adequate soil volume and appropriate root management measures help minimise the likelihood of conflicts.
The most effective approach is to provide sufficient soil volume, use structural support systems where appropriate, and incorporate root management measures into the tree pit design. Designing the correct below-ground environment from the outset encourages roots to grow where they are intended rather than beneath the pavement.
