RootSpace Load-Bearing Performance: Supporting Trees and Urban Infrastructure
Urban trees need access to sufficient uncompacted soil to grow successfully. At the same time, pavements and trafficked areas need a strong and reliable structure beneath them.
RootSpace is designed to provide both.
Its interlocking soil cell system creates a structural underground framework that supports the surface above while maintaining valuable soil volume for tree roots below.
Yes. RootSpace has been designed for use beneath urban surfaces where structural performance is required.
The system uses an engineered lattice structure that connects together to form a continuous underground framework. When installed correctly, the interconnected cells distribute loads and provide lateral stability while protecting the uncompacted soil within the rooting zone.
This makes RootSpace particularly relevant for urban environments where trees are located alongside:
RootSpace is engineered to work as a continuous, interlocking system.
The connection between individual cells is important because the structural performance of the system depends on the cells acting together rather than as isolated units.
According to the Mind the Gap technical resource, introducing gaps between soil cells can reduce static load capacity, compromise lateral rigidity and allow movement within the surrounding backfill.
For that reason, RootSpace should be installed as a fully connected system in accordance with its engineered configuration.
One of the key benefits of RootSpace is the ability to combine structural support with a high volume of soil for tree roots.
The system provides approximately 95% soil void space, allowing the RootSpace structure to be filled with suitable soil while the surrounding lattice provides structural support.
This helps create a stable pavement structure above while maintaining a largely uncompacted growing environment below.
For urban trees, this is important because adequate soil volume gives roots more opportunity to develop within the designed rooting area.
Urban tree pits can be exposed to different types of loading.
A parked or stationary vehicle creates a static load, while moving vehicles introduce dynamic loading.
The RootSpace technical resource illustrates its use under both conditions and explains that a correctly configured, interlocking system provides the structural rigidity required for trafficked environments.
RootSpace has also undergone independent structural testing by Lucideon, an independent materials testing and analysis laboratory.
The testing programme assessed the structural integrity and load-bearing capacity of different RootSpace configurations.
Testing was carried out to BS EN 17150:2019 and included Uniformly Distributed Load testing to examine compression strength and deflection characteristics. During testing, samples were subjected to compression while load and deflection were continuously monitored.
The testing covered different RootSpace 400 and RootSpace 600 configurations, with and without infill panels.
The results demonstrated the structural performance of the assembled system and provided data on maximum loads and deflection under compression. The technical resource also highlights the system’s strong lateral load-bearing characteristics and resistance to sideways forces.
RootSpace G2 is certified by the British Board of Agrément (BBA), providing independent third-party verification of its structural performance and durability.
BBA certification is particularly valuable for specifiers because it provides external assurance that the product has been assessed for its intended use, rather than relying solely on manufacturer test data.
For RootSpace, this additional layer of verification supports confidence in its load-bearing capability, product consistency and long-term performance beneath paved and trafficked urban environments. GreenBlue Urban states that RootSpace is the only BBA-certified soil cell system in the UK.
The way a soil cell system is installed is just as important as the strength of the individual components.
Leaving gaps between cells can create several potential problems:
The technical guidance also notes that geotextile alone cannot compensate for unsupported gaps between cells. In these circumstances, additional structural measures such as concrete may be required, increasing cost, complexity and embodied carbon.
A continuous RootSpace installation avoids these unnecessary voids and allows the system to perform as engineered.
The purpose of RootSpace is not simply to support pavement.
It allows designers to create a structurally stable urban environment while also providing trees with access to uncompacted soil.
Its combination of:
makes RootSpace well suited to urban tree pit applications where trees, pavements and vehicle movements need to coexist.
For load-bearing applications, RootSpace should be designed and installed as a complete, interconnected system.
The correct RootSpace configuration will depend on the project layout, required soil volume, surface build-up and loading conditions.
Greenleaf Ireland can assist landscape architects, engineers, contractors and local authorities with selecting and detailing the appropriate RootSpace solution for an urban tree pit.
Planning a load-bearing tree pit? Contact Greenleaf Ireland to discuss the RootSpace configuration for your project.
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