Why Install a Root Barrier?
Root barriers are required for all sorts of reasons, namely to protect property and underground cables from spreading tree roots. Trees can have extensive root masses which spread far from the tree base. Roots are extremely important for trees as they help the tree to gather nutrients and water and are also needed for stability. Unfortunately, roots can cause problems for both home owners and commercial buildings owners as they are apt to cause structural damage to concrete slabs and also movement to buildings. City councils also have issues with tree roots moving and lifting pavement slabs causing dangerous trip hazards to the general public.
Inserting a root barrier around a tree is:
- Environmentally Friendly
- Effective and preventative
- Cost effective
- Eliminates the need for a tree to be removed in order to protect property
Prior to Vacuum Excavation trucks being available, root barriers would have been dug by hand which would be hard, physical and time consuming labour. Excavator diggers were also used to dig trenches at great risk to underground utilities and the tree itself. Using Vacuum Excavators to dig trenches for root barriers eradicates the risk to underground pipes and utilities and is a much safer option for the tree.
Tree Protection Zone:
A root barrier installation should always be overseen by an experienced and qualified arborist who understands tree biology and growth patterns. They will know the best position to insert the root barrier and how to protect the roots so that the tree remains healthy. The trench must always be dug outside of the Structural Root Zone (SRZ) to protect the tree and within the Tree Protection Zone (TPZ). The calculations to ascertain the protection zones are based on the Australian Standard AS4970-2009 Protection of Trees on Development sites.
How it works:
The Arborist will locate the tree roots by using the perimeter of the tree’s canopy as a guide. Using a Vacuum Excavation wand (a high-powered hose) to remove soil and clay, the tree roots will be exposed. A root barrier trench can either be dug out in a semi-circle around the tree or in a straight line alongside a fence line for example. Generally, a trench is 900 mm deep and 100mm wide but can be dug to any size requirements. Once the tree roots have been located the soft wand is used to expose the roots while keeping the Cambial layer (skin) intact as this will protect them. If the cambial layer is removed the tree roots will die thus great harming the tree’s, chances of survival.
Once the tree roots are exposed and the trench is dug, the tree roots are cut and a natural honey solution is used to treat the ends of the cut roots. The honey seals the cut root ends and reduces the risk of fungus and pests. A specially designed root barrier material can then be positioned within the trench. Next a layer of Bentonite (greyish, white granules which hardens into a clay substance which tree roots will not penetrate) is poured onto the trench, followed by a layer of soil and then another layer of Bentonite. Finally, the root barrier is back filled with garden soil and it should be unnoticeable that a root barrier is in place.