Invasive tree roots can lift paving, enter damaged pipes and compete with nearby planting. First identify what the roots are damaging. Then choose a control that addresses the problem without destabilising the tree.
Some situations call for completely removing invasive tree roots and regrowth. In many gardens and landscape projects, though, a root barrier, better planting position or professionally planned root pruning is the safer answer.
Tree roots grow towards usable soil, water and nutrients. Problems arise when that growth reaches pipes, paving or footings.
Willows, poplars, liquidambars and some large eucalypts are often involved in root conflicts in Australian landscapes. Species alone does not determine the risk. Mature size, soil depth, available moisture and the distance to paving or services all matter.
Root damage often starts quietly. A lifted paver, recurring drain blockage or root appearing beside a footing deserves investigation before anyone starts cutting.
Urban tree root systems tend to spread widely through usable soil. The peer-reviewed review The Management of Tree Root Systems in Urban and Suburban Settings explains why root location, structural stability and infrastructure conflicts must be considered together.
Dry soil can send roots towards more reliable moisture. Damaged or leaking pipes can then provide a favourable growing environment, so the pipe defect and the roots may both need attention.
Trees most likely to cause trouble in Australia are vigorous species planted too close to paving, drains or footings for their mature size. Willows, poplars, liquidambars and large eucalypts are common examples, but a well-sited tree may coexist with infrastructure while a smaller tree in confined soil may not.
Before planting, check the tree's expected mature canopy and root space, local council requirements and the position of buried services. For an existing tree, identify the species and inspect the site rather than assuming every surface root is invasive.
Investigate lifted paving, recurring drain blockages or new cracking early, before the damage worsens.
Common symptoms of root invasion include:
Sticking doors or windows can also point to foundation movement, although roots are only one possible cause.
If you notice several symptoms near a large established tree, arrange an arborist, plumber or structural assessment suited to the damage. Root cutting without a diagnosis can harm stability and still leave the underlying pipe or pavement defect unresolved.
Before doing any work, confirm the source of the damage and locate buried services and structural roots. Use the least disruptive suitable method, then check the site afterwards. Cutting the first visible root is rarely a long-term plan.
Send your trench depth, length and site plan when you ask All Stake Supply about root barrier rolls and joining tape.
A root control barrier is a physical membrane made from durable, flexible high-density polythene. Installed between a tree and the area being protected, it redirects roots away from footings, pipes, garden beds or paved surfaces.
The barrier does not make roots disappear. Roots may travel downwards, along the face of the membrane or around its ends, which is why depth, length, placement and sealed joins all affect the result.
Installation around a new planting can guide growth without cutting established roots. Retrofitting a barrier beside a mature tree needs more care because trenching may sever structural or absorbing roots.
See how tree barriers work and where they can be used before setting out the trench.
Choose the barrier for the roots, soil and asset at the site.
Depth and thickness matter, but so do the trench route, root location and the asset being protected.
For a residential project with a shallow specified trench, a 450 mm root barrier roll may suit where the site assessment supports that depth.
A 500 mm root barrier roll provides an intermediate option. Where the design calls for a deeper membrane, the 600 mm root barrier roll extends the protected depth without implying that every mature root system sits above it.
All three rolls use a 1000 micron membrane. Choose among them from the actual trench design, root location and protected asset, rather than tree height alone.
Barrier performance depends on the trench route, depth and joins. Professional input is sensible for large projects, public sites and any trench close to a mature tree or valuable infrastructure.
Locate buried services before excavation. Then confirm that the proposed trench will not remove roots that are important to tree stability.
Use this installation sequence as a planning checklist:
When installing around an existing tree, let the arborist's inspection determine the trench route and timing. For new plantings, putting the barrier in first avoids cutting an established root system later.
Root barrier depth must match the roots and asset at the actual site. Soil profile, drainage, tree species, available root space and the barrier's distance from the trunk are more useful than a one-size-fits-all rule based on tree height.
| Barrier option | Where it may fit | What to confirm first |
|---|---|---|
| 450 mm | Shallower landscape trenches and new planting designs | Root depth and the level of the asset being protected |
| 500 mm | Projects needing a middle depth between standard roll sizes | Trench clearance, joins and end points |
| 600 mm | Deeper specified trenches and larger infrastructure interfaces | Structural roots, buried services and safe excavation access |
Root barriers can be installed near mature trees, but only after the proposed trench and roots have been assessed. A barrier is not a safe retrofit if its installation would remove roots needed for stability or tree health.
The arboriculture review cited above documents the consequences of root severing and the importance of locating roots before work. Some Australian councils require an arborist inspection before root pruning or barrier installation; the City of Boroondara's tree-root process is one example.
Newly planted trees may need guards, mulch and suitable watering while they establish. A barrier can redirect roots where the site design requires it.
Tree guards shield saplings from wind, pests and mechanical damage. Read about regulating root growth with root barriers when planning both systems together.
For young plantings in landscaping projects, Corflute tree guards in a 100-pack shield trunks from line trimmers and browsing animals while the trees establish.
Stake only where needed, and keep stakes outside the barrier zone.
Mulch helps retain soil moisture, but it does not reliably force roots downwards or away from a barrier.
Spread mulch over the root zone without piling it against the trunk. Organic woodchip or bark mulch can moderate moisture loss and improve surface soil as it breaks down.
Water for the species, soil and season rather than keeping one small patch beside the trunk constantly wet. For irrigation projects, place emitters so the tree has usable soil on the safe side of the barrier instead of encouraging roots towards the protected asset.
For newly planted trees near existing barriers, 600 mm jute weed mats suppress competing vegetation while allowing water through to the soil.
A root barrier is one control method, not the answer to every conflict. Pipe repair, pavement redesign, irrigation changes and professional root pruning may be more appropriate once the cause is confirmed.
Mechanical root pruning removes selected roots, but it can affect tree health or stability and regrowth remains possible. Have an arborist specify which roots can be cut, where to cut them and whether the crown or site needs follow-up work.
Choosing a species that fits the available root space can prevent many conflicts. Reserve vigorous growers for open ground away from infrastructure.
Consider these alternatives based on your specific situation:
Inspect the barrier periodically, with the frequency based on the risk and the asset it protects.
Check that barrier tops remain visible above ground level. Mulch accumulation or soil movement can bury barrier edges, allowing roots to grow over the top.
Inspect for surface roots growing near barrier perimeters. If roots are growing around an end, ask the installer or arborist whether the barrier needs extending.
Monitor protected structures for any signs of ongoing root damage. If new cracks appear despite barriers, professional assessment can determine whether roots have found pathways around or under the installation.
Document barrier positions carefully for future reference. Mark them on property plans so later landscaping or construction work does not cut through the membrane.
Keep the inspection proportionate to the risk. A barrier beside a garden path may only need a visual check, while one protecting a drain, footing or public asset should form part of the site's planned maintenance.
Use a correctly positioned root barrier to redirect growth away from the asset, then make sure the tree has adequate soil and water on the other side. If roots are already established, have an arborist assess them before trenching or pruning.
They can, if they are specified and installed for the site. Poor depth, unsealed joins or exposed ends give roots a way around them.
Do not pour herbicide, salt or other chemicals onto living roots. For a tree you intend to retain, physical separation, pipe repair, irrigation changes and arborist-planned pruning are safer control options.
"Cedar" is used for several different trees, so the name alone does not tell you how the roots will behave. Identify the species, mature size and available root space, then assess its distance from drains, paving and foundations.
Possibly. The risk depends on the root's size and position, how many roots would be removed and the tree's condition, so major roots need an arborist's assessment.
Call an arborist before cutting major roots or trenching near a mature tree. Bring in a plumber for recurring drain problems and a structural professional where cracking or movement affects a building.
All Stake Supply carries root barrier rolls, joining tape, tree guards and establishment products for residential, landscape and civil projects. Browse the full landscaping product range or speak with the team about the quantities shown on your site plan.
