Trees are one of the best features of any Sydney property. They provide shade during scorching summers, improve air quality, add privacy and boost street appeal — which is why many homeowners invest in professional tree services to keep them healthy and well-maintained. But when a tree becomes structurally unstable or diseased, it can quickly turn from an asset into a serious safety risk.
With Sydney’s mix of coastal winds, heavy rainfall, clay soils and tall native species like eucalypts, tree failures are not uncommon — particularly after storms. The challenge is that dangerous trees don’t always look obviously unstable until something goes wrong.
Below are 10 warning signs that a tree in your Sydney yard may be unsafe, what they mean, and when it’s time to seek a professional opinion.
1. A Sudden Lean or Increasing Tilt
A slight lean doesn’t always mean a tree is dangerous. Many trees naturally grow at an angle, especially if they’ve adapted to reach sunlight. However, a sudden lean — particularly after heavy rain or storms — is a red flag.
When is a leaning tree dangerous?
A tree may be unsafe if:
• The lean has recently worsened
• The soil around the base is cracked or lifted
• Roots are visible or exposed on one side
• The trunk appears to be pulling away from the ground
Western Sydney’s clay-heavy soils can expand when wet and shrink during dry spells. This movement can destabilise root systems over time.
If you notice fresh movement, don’t ignore it. A tree that shifts once can continue shifting until it fails.
2. Cracks in the Trunk
Vertical or horizontal cracks in the trunk can indicate structural weakness. While some bark splitting is natural, deep cracks extending into the wood are more concerning.
Cracks may:
• Weaken the tree’s load-bearing capacity
• Allow moisture and pests inside
• Signal internal decay
Large trees under tension — particularly tall eucalypts — are vulnerable to splitting during strong winds. A cracked trunk is not something to monitor casually. It often requires a professional arborist assessment to determine structural integrity.
3. Large Dead Branches (Deadwood)
Dead branches are one of the most common warning signs of instability.
Why is deadwood dangerous?
Dead branches:
• Become brittle and prone to snapping
• Fall without warning
• Increase during drought stress
• Are more likely to drop in high winds
Sydney’s hot summers can stress trees, leading to canopy dieback. Even a single heavy limb falling from height can cause severe injury or property damage.
If deadwood is visible in upper canopy areas, it’s worth having it inspected by licensed tree experts in Sydney before storm season arrives.
4. Fungal Growth at the Base
Mushrooms or bracket fungi growing near the trunk base often indicate internal decay.
Fungi feed on decomposing wood. When visible externally, internal rot may already be advanced.
Does fungus always mean a tree is unsafe?
Not always, but it significantly increases risk. Warning signs include:
• Soft or crumbly wood near the base
• Hollow sounds when tapped
• Bark separating from the trunk
• Sudden limb drop
Root or butt rot compromises anchoring strength. In severe cases, trees can uproot entirely during storms.
5. Soil Heaving or Root Plate Movement
After heavy rainfall, inspect the soil around your tree.
If you notice:
• Raised or cracked soil on one side
• Gaps forming around roots
• Freshly exposed roots
The root plate may be shifting.
Sydney experiences intense rainfall events, particularly during summer east coast lows. Saturated soil reduces root grip, increasing the risk of windthrow.
Trees rarely fall “without warning” — root movement is often an early indicator.
6. Hollow Trunk or Cavities
Hollow trees are common in Australia, especially among older native species. Some hollows are stable and harmless. Others compromise structural strength.
When is a hollow a serious problem?
Risk increases when:
• The hollow is large relative to trunk diameter
• There’s visible decay inside
• The tree leans
• Multiple cavities exist
Arborists often use assessment tools to evaluate remaining structural wood thickness. Without proper inspection, it’s impossible to determine whether the hollow is cosmetic or dangerous.
7. Sudden Canopy Dieback
If leaves are thinning, branches are bare, or large sections of the canopy have died off, the tree may be under severe stress.
Common causes in Sydney include:
• Extended drought periods
• Root damage from construction
• Soil compaction
• Pest infestation
• Fungal disease
Significant canopy loss reduces a tree’s ability to support itself structurally. In some cases, root systems may already be failing.
Dieback across one side of the tree can indicate root damage on that same side — a structural imbalance that increases fall risk.
8. Excessive Branch Drop (Especially in Eucalypts)
Eucalypts are iconic in Sydney landscapes but are known for “sudden limb drop.”
This phenomenon can occur:
• On hot, still days
• Without visible wind
• In otherwise healthy-looking trees
Large limbs can detach unexpectedly, posing serious danger.
If your property includes mature gums near high-traffic areas — driveways, patios, play spaces — proactive monitoring is essential. Repeated branch drop is a sign that the tree may need closer evaluation.
9. Pest Infestation or Borer Activity
Termites, borers and other pests can weaken internal wood structure.
Signs include:
• Small holes in bark
• Sawdust-like material at the base
• Peeling bark
• Hollow-sounding trunk
While not all infestations are catastrophic, advanced internal damage significantly reduces structural integrity.
In urban Sydney settings, stressed trees are more vulnerable to pests. Early detection can prevent full failure.
10. Storm Damage That Was Never Assessed
After severe weather, many homeowners clean up visible debris but overlook structural damage.
Check for:
• Split limbs
• Hanging branches
• Partial trunk fractures
• New learning
• Torn root systems
Even if the tree remains standing, internal stress fractures may worsen over time.
If your tree experienced heavy storm exposure, especially during recent high-wind events across NSW, a precautionary inspection is wise.
Who Is Responsible for Dangerous Trees in NSW?
In NSW, property owners are generally responsible for trees located on their land. If a tree falls and causes damage, liability can depend on whether the owner acted reasonably to manage known risks.
According to the NSW Planning Portal, certain tree removals may require council approval depending on local regulations and tree preservation orders. It’s important to check your local council requirements before undertaking major work.
Ignoring visible warning signs could potentially expose homeowners to disputes or insurance complications if damage occurs.
When Should You Act Immediately?
Seek urgent professional advice if:
• The tree has shifted suddenly
• Large limbs are hanging or cracked
• The trunk has split
• Roots are lifting from the soil
• The tree is leaning toward a house, driveway or neighbouring property
These are not “wait and see” situations.
In these cases, arranging a professional arborist assessment can help determine risk level and next steps.
When Monitoring May Be Enough
Not every issue requires immediate removal.
Monitoring may be appropriate when:
• Lean is long-standing and stable
• Minor surface cracks are present
• Small dead branches exist
• Fungal growth is superficial
However, if multiple warning signs appear together, risk increases significantly.
Why Sydney’s Environment Increases Tree Risk
Sydney presents unique environmental factors:
• Coastal wind exposure
• Intense summer storms
• Clay-heavy soils in Western suburbs
• Periods of drought followed by heavy rain
• Large native species prone to limb drop
These combined conditions mean trees can deteriorate internally long before obvious external collapse.
Preventative inspection is far safer — and often more affordable — than emergency response.
Frequently Asked Questions
Can a tree fall without warning?
Rarely. Most trees show early indicators such as soil movement, cracking, dieback or fungal growth. These signs are often subtle but detectable.
Is a leaning tree always unsafe?
No. Many trees grow naturally at an angle. Concern arises when the lean is new, increasing, or accompanied by root disturbance.
Does fungus mean the tree must be removed?
Not automatically. Some fungi are superficial. Others indicate advanced internal decay. Proper assessment determines severity.
What if my neighbour’s tree looks dangerous?
If the tree is on your neighbour’s property, discuss concerns with them first. In NSW, owners are generally responsible for maintaining trees on their land.
Do I need council approval to remove a dangerous tree in Sydney?
It depends on your local council’s regulations and whether the tree is protected. Always check before proceeding.
The Value of Professional Evaluation
Visual inspections by homeowners are helpful, but structural risk assessment requires expertise.
Qualified arborists evaluate:
• Structural integrity
• Root stability
• Decay progression
• Species-specific behaviour
• Risk likelihood
For broader property maintenance and preventative management, comprehensive tree care solutions may reduce long-term safety risks.
Final Thoughts
Trees are valuable, beautiful and essential to Sydney’s urban landscape. But like any living structure, they can become unstable over time.
If you’ve identified one or more of the warning signs above, it’s worth taking action sooner rather than later. A professional arborist assessment can help determine whether monitoring, maintenance or removal through appropriate tree services is the safest option.
Early attention protects:
• Your home
• Your family
• Your neighbours
• Your legal responsibility
Safety should always come first.