Root Investigation

What is a Root Investigation?

How to get a Root Investigation

Send photos of the damage and the trees nearby, and roughly how far apart they are. We will tell you which method suits the site, quote it as a fixed price, and check whether the tree is protected before anything is dug. The report follows within 2 to 3 business days of the site work.

Tree roots damaging your house?

Roots rarely push a house over on their own. What they do more often, on the reactive clay soils common across South East Queensland, is dry the soil out. A large tree draws moisture from the clay under one side of a slab or footing, the clay shrinks, and that side settles: cracks that open in dry months and close in wet ones, doors that stick, and a slab that is no longer level.

The investigation establishes whether roots are actually under the footings, whose tree they come from, and whether the movement follows the tree or something else, such as a leaking pipe, poor drainage or the way the slab was built. Where the structure needs assessing too, it is done alongside a structural engineer, so the arboricultural and engineering findings agree.

Tree roots lifting your driveway or path?

Surface roots thicken every year, and a driveway, path or pool surround laid over them gets lifted and cracked. Before the surface is repaired or a root barrier goes in, the roots need finding: which ones can be cut, which are structural and holding the tree up, and where a barrier line would actually work.

Cutting the wrong root fixes the driveway and destabilises the tree. Locating them first, usually with an air spade along the proposed cut line, is what makes the repair safe.

Tree roots in sewer or stormwater pipes?

Roots do not usually break a sound pipe. They find a cracked joint, an old earthenware section or a loose connection, follow the moisture in, and fill the pipe from the inside. Clearing the blockage treats the symptom, and it comes back.

A plumber’s CCTV camera shows where the roots are getting in. The investigation then traces those roots back to the tree, identifies the species where it is not obvious, and sets out the fix: repairing or relining the pipe, a root barrier along the line, root pruning, or in some cases the tree itself. It also settles whose tree it is, which matters when the pipe or the tree is on the other side of a fence.

Which tree is causing the damage?

Often the obvious tree is not the culprit. Roots travel well beyond the canopy, and on a suburban block the roots under your slab can belong to your tree, your neighbour’s, or a street tree. Proving which one is what decides who pays and what can be done about it.

Roots are traced from the damage back towards each candidate tree, and where tracing alone cannot settle it, root samples go to a laboratory for identification by their anatomy, or by DNA where species are similar. The report states which tree the roots belong to and how that was established.

Root investigation methods

We use every method, and choose by what is being damaged, what is over the roots, and what the result has to stand up to. Each produces its own kind of report.

Root investigation for development (AS 4970)

Under AS 4970:2025, encroaching into a tree’s notional root zone by more than 10% has to be justified, and one of the ways to justify it is a root investigation showing where the roots actually are. Where the investigation finds few or no significant roots in the area to be built on, the encroachment can be accepted that the calculation alone would not support.

Investigations for development are usually non-destructive, by air spade or GPR along the edge of the proposed works, and they feed straight into an arboricultural impact assessment. The TPZ calculator shows the zones it starts from.

Tree root damage and insurance claims

Tree root claims usually turn on three questions an insurer or loss adjuster cannot answer from photos: did roots cause the damage, whose tree are they from, and how long has it been happening. The investigation answers each with the evidence behind it, in a report written to the standard of expert evidence, so it holds up if the claim or a recovery is disputed.

Check your policy early. Many home insurance policies exclude gradual damage such as root intrusion, and where the roots come from a neighbour’s tree, the claim may lie with the neighbour or their insurer instead.

Root investigation cost

Every root investigation is quoted per job, as a fixed price before any work starts. What moves it:

The report follows within 2 to 3 business days of the site work.

Root investigation across South East Queensland

Root investigations are carried out across Brisbane, Moreton Bay, the Sunshine Coast, the Gold Coast, Redland, Logan and Ipswich. Digging around a protected tree can need council approval even when nothing above ground is touched, so the tree’s protection is checked before any excavation, and any approval is handled as part of the job. The rules for each council are set out separately.