Trees can be a significant problem within developed areas if left unchecked, so root control is an essential consideration on all projects in the vicinity of existing trees, or where new tree planting is planned. Trees that are left to grow out of control in urban environments, adjacent to structures, roads and pathways may eventually push beyond their envisaged area of influence at the time of planting and create severe issues. Uncontrolled growth may ultimately cause damage to infrastructure and affect the functionality of systems and services potentially leading to costly repairs and/or reduction in property value. Common damage caused by tree roots includes cracked pipework, broken and uneven pavements on asphalt and blockwork, and structural damage to building foundations and walls. Prevention is likely to be considerably more cost-effective than cure hence it pays to consider potential issues at an early stage.
Root barriers are very effective tools in the fight against root migration and subsequent potential damage as they contain, control and re-direct root growth away from susceptible structures and services.
TCS Geotechnics offers two basic types of root barrier – permeable and impermeable. In general, impermeable barriers are reserved for vertical installation as they clearly provide a barrier to water flow and if laid horizontally are likely lead to issues of trapped and ponded water and associated boggy ground. For horizontal applications, we would suggest a permeable root barrier that clearly allows water to flow through and avoid the above water entrapment issues.
Impermeable Root Barriers – Plantex® RootBarrier & Terram® Rootguard Plus
Permeable Root Barriers – Plantex® RootProtector & Terram® Rootguard
PREVENT DAMAGE TO PIPES AND OTHER SERVICES
Tree roots finding their way into pipes will eventually lead to blockages and are a major cause of blocked drains. Not only will the roots cause a drain to be blocked but as the root grows, it applies pressure and will potentially crack the pipes.
The tree root seeks to find any moisture in the ground, and any pipes with even minor leaks become targets for tree roots seeking out a water source. Initially, tree roots don’t cause cracks but as the small roots grow and thicken they cause damage. Repairing cracked drains can be time-consuming and expensive, particularly with deeper pipes. Using root barriers is a cost-effective and simple solution to the problem of root invasion and service damage. The root barriers can be laid horizontal or vertical depending on the application. With an anticipated lifespan of 100 years, root barriers can be installed either before new tree planting or between proposed service corridors and existing trees, enabling the trees to potentially grow for decades around the barrier and keeping the services protected well into the future.
USING ROOT BARRIERS FOR STRUCTURES
Prevention of structural damage by tree roots is another key application of root barriers. Letting a tree grow too close to a structure can cause severe issues, not just from the root pressure but also related to the potential fluctuation in soil moisture content. Tree roots drawing moisture from certain soils, particularly some clays, may cause shrinkage and settlement which can be severe enough to damage structures. Similarly a tree with roots close to a structure which dies, or is cut down, will clearly stop drawing water from the soil and may lead to soil expansion and heave, potentially damaging structures.
Installing a root barrier around a building or tree to prevent the ingress of roots into unwanted areas will avoid this issue. When considering the proximity of existing or proposed trees to structures it is strongly recommended that advice is sought from a suitably qualified professional as the soil and tree types have a very significant bearing on the issue and the precautions required.
PREVENTING TREE ROOT DAMAGE TO PEDESTRIAN WALKWAYS
Root heave is a key symptom of uncontrolled tree growth in urban areas and can effectively destroy pedestrian walkways. It is evidenced by cracked and broken surfaces which not only encourage further damage, via erosion, water ingress, and frost but also present a safety trip hazard for pedestrians.
For new planting, the anticipated root growth space can be vertically lined with an impermeable product like Plantex® Rootbarrier or Terram® Rootguard Plus. This has the intention of containing the rootball within a defined space and inhibiting the uncontrolled spread of root growth.
Root Barrier surrounds the tree roots and the tree root growth is contained. The hardscaping and ground are intact and damage-free and the tree remains healthy with space for its roots and sufficient access to water.
If a horizontal root barrier is required beneath say a path or road then a permeable product should be used like Plantex® Root Protector or Terram® Rootguard. As indicated below, the Root Protector inhibits the growth of roots up into the roadway but the permeable nature of the root barrier allows water to reach any underlying roots, keeping the associated trees healthy.