Tree Root Damage to Pipes and Foundations: What Sydney Homeowners Must Know

Book a Root Zone Assessment before excavation or major root cutting commits the property to the wrong repair.

Warning Signs of Root Intrusion on Your Property

A tree root blocking drain Sydney problem may show through:

• repeated slow drains
• gurgling toilets or sinks
• sewage smells inside or outside
• wastewater backing up through lower drains
• damp, sunken or unusually green ground above a pipe
• recurring blockages after root cutting
• cracked terracotta found during CCTV inspection
• lifted pavers, kerbs or lightweight garden walls
• new wall cracks or doors beginning to bind

One sign alone may not identify the cause. A blocked drain might come from grease, damaged pipework, soil movement or poor installation.

Ask the plumber to keep the CCTV file and mark the damaged section on a plan. Ask the arborist which trees could have roots within that area and whether root pruning may affect tree stability.

Which Tree Species Have the Most Aggressive Roots?

There is no reliable “worst tree” list for every Sydney property. Large, fast-growing or moisture-seeking trees may create a higher risk near ageing pipes, yet a small shrub can enter an open joint.

Groups often checked during root investigations include:

• figs
• eucalypts
• melaleucas
• willows
• poplars
• liquidambars
• plane trees
• privets
• running bamboo

Plateau Trees’ guide to trees with invasive root species outlines several plants that need careful placement near buildings, drains and paved areas.

Species Is Only One Part of the Risk

Root-related pipe risk is higher where there are:

• old terracotta or earthenware drains
• shallow pipework
• leaking joints
• large trees close to service lines
• dry or compacted soil
• restricted garden beds
• repeated drain clearing without pipe repair
• major differences in moisture across the site

Treat invasive tree roots as a site issue rather than a label applied to every tree of a certain species.

For future planting, choosing trees with non invasive roots may reduce pressure near paved areas, retaining walls and underground services. Planting distance, mature size and local soil conditions still need to be checked.

Tree Root Damage to Home Foundations: What Actually Happens

Roots can affect buildings in two main ways.

Direct Physical Movement

A woody root may lift paving, a lightweight wall, a driveway edge or a shallow footing when it grows through a confined space. Direct pressure against a properly built house foundation is less common.

Soil Moisture Change

Roots draw moisture from the soil. Sydney properties with reactive clay may experience uneven soil shrinkage during dry periods. This can reduce support under part of a footing and contribute to movement.

CSIRO guidance notes that roots near footings may cause shrinkage or subsidence through moisture removal. Leaking stormwater lines, poor drainage, variable soil compaction and older building methods may contribute to the same symptoms.

Possible signs of tree root damage foundation concerns include:

• diagonal cracks near windows or doors
• doors that rub or no longer close
• gaps around frames
• uneven flooring
• cracked external paving
• movement that becomes more noticeable during dry weather

Structural wall cracks wider than 5 mm may warrant assessment by a structural engineer. Smaller cracks may still need inspection when they are new, increasing or paired with drainage problems.

Removing a mature tree before the cause is confirmed can create a new moisture change in the soil. The building, drainage system, soil and tree should be assessed as connected site elements.

Who Is Responsible When a Neighbour’s Tree Damages Your Property?

Neighbour tree responsibility in NSW depends on evidence, tree ownership, pipe ownership and the location of the damage.

Property owners are commonly responsible for private water and wastewater pipes up to the relevant connection point. Sydney Water says owners are responsible for clearing roots that enter the junction at that point and for related repairs, subject to its inspection and ownership rules.

Where roots come from a tree on adjoining private land, the Trees (Disputes Between Neighbours) Act 2006 may allow an owner to apply to the NSW Land and Environment Court. The Court can order tree work, allocate costs and award compensation in qualifying cases.

Before starting a formal claim, review Plateau Trees’ guide on who may be responsible for taking care of tree problems. It explains why location, ownership and supporting evidence matter.

What Evidence May Be Needed?

A claim may need to show:

• where the tree is located
• where the damaged pipe or structure is located
• which roots entered the damaged area
• the condition of the pipe before repair
• whether the owner was warned about the problem
• the cost of repair
• reasonable attempts to resolve the dispute

For strata property, the owners corporation usually repairs common property. Individual owners are commonly responsible for items within their lot. Pipe location and strata boundaries can change the answer, so the matter should be reported to the strata manager before non-urgent repairs start.

For a council tree, notify the council before the damaged pipe is covered. Keep photos, CCTV footage, repair quotes and reports from the plumber or arborist.

This information is general and is not legal advice.

Root Barrier Installation: Does It Work?

A root barrier may redirect roots away from a pipe, wall, driveway or paved area. It is most useful after the damaged pipe has been repaired and where the remaining root system has enough healthy soil.

A research review found that barriers reduced roots outside the protected area by 35% to 55% in cited trials. Results vary with barrier depth, soil, installation quality and tree species.

Roots may:

• grow beneath a shallow barrier
• follow the barrier edge
• return through gaps
• move closer to the surface
• grow around the end of the barrier

A barrier may be unsuitable when installation would cut major structural roots, disturb utility lines or leave the tree unstable. It is a site control, not a permanent guarantee.

Root Barrier or Pipe Relining?