A possum in your roof makes a heavy, irregular thumping sound between 9pm and 4am — distinctly different from the lighter, faster scurrying of rats. A brushtail possum weighs 1.5 to 4.5 kilograms, so the noise is closer to a small human walking around in the ceiling cavity than a rodent.

If you suspect a possum has moved into your roof cavity, you need to confirm it quickly. The longer a possum stays, the more damage it does to insulation, wiring, and timber. And because possums are protected native wildlife in Australia, removing one yourself is illegal in every state.

This guide covers the six most reliable signs of a possum in the roof, explains why DIY removal is against the law, and walks through what a professional possum removal service does that you cannot do yourself.

6 Signs You Have a Possum in Your Roof

Here are the six most common signs that confirm a possum is living in your roof cavity. If you have more than one, the situation is almost certain.

Sign 1: Heavy Thumping Between 9pm and 4am

This is the most obvious sign. A brushtail possum weighs 1.5 to 4.5 kilograms — it sounds like a small human walking across the ceiling. The footsteps are slow, deliberate, and irregular. Rats are fast and light. If the noise makes you think "that sounds too heavy to be a rat," you are probably right. See our possum vs rat guide for a full comparison.

Sign 2: Ammonia Smell in Ceiling Areas

Possum urine has a sharp, strong ammonia smell that is noticeably different from rodent odour. You will notice it most in rooms below the roof cavity, especially on warm days or after rain. The smell intensifies the longer the possum has been living in the roof.

Sign 3: Scratch Marks on Fascia Boards at Eave Height

Possums leave scratch marks on fascia boards, eaves, and roof timbers where they enter and exit. These marks are most visible at dusk or dawn when the possum is moving in or out. Look for fresh claw marks on timber near lifted tiles or gaps in the roofline.

Sign 4: Possum Droppings in the Roof Cavity

Possum droppings are dark, cylindrical, 1–2 cm long with tapered ends — the size of an olive pit. They are usually found in piles on top of insulation or along roof joists. If you have found droppings, check our detailed guide on how to identify possum droppings to confirm the species.

Sign 5: Chewed Timber or Insulation

Possums chew timber and insulation as part of territory marking behaviour. They gnaw on roof beams, electrical wiring, and ductwork. Chewed insulation often looks like it has been pulled apart rather than bitten through cleanly. Damaged wiring can create fire risks if left unaddressed.

Sign 6: Visual Sighting at Dusk Using a Tree Branch to Access the Roof

If you see a possum climbing a tree branch that touches your roofline at dusk, it is almost certainly denning in your roof cavity. Possums are creatures of habit — if you see one use a particular branch or power line to reach the roof, it has been using that same route every night. This is the most definitive sign of all.

If you have confirmed multiple signs, the next question is what to do about it — and the answer is almost always to call a licensed professional. For homeowners in Brisbane, a local possum removal service can inspect and handle the problem lawfully.

Why DIY Possum Removal Is Illegal in Every Australian State

Possums are protected native wildlife under Australian law. You cannot trap, handle, or remove a possum yourself without a licence — no matter which state you live in. Doing so can result in significant fines and legal action.

Here are the maximum penalties for unauthorised possum handling in each state:

• New South Wales: Up to $11,000 fine under the Biodiversity Conservation Act
• Victoria: Up to $9,900 fine under the Wildlife Act
• Queensland: Up to $25,740 fine under the Nature Conservation Act — the strictest in the country
• Western Australia: Up to $10,000 fine under the Biodiversity Conservation Act
• South Australia: Up to $5,000 fine under the National Parks and Wildlife Act

Beyond the fines, DIY removal often makes the problem worse. Blocking an entry point with the possum still inside can kill the animal, creating a severe odour problem that requires dead possum removal services. Improper handling can also result in bites or exposure to diseases carried by possum waste.

The only lawful approach is to engage a licensed possum removal operator who holds the appropriate permits and follows your state's wildlife regulations.

What Professional Possum Removal Does That You Cannot

Licensed possum removal operators have tools and legal authority that homeowners do not. Here is what a professional service provides that you cannot do yourself:

• Thermal imaging inspection. Professionals use thermal cameras to locate the exact den site inside the roof cavity without having to tear apart insulation or ceiling sheets.
• Approved trap placement. Only licensed operators can use approved possum traps that comply with state animal welfare regulations. Homemade traps can injure the animal and land you with a cruelty charge.
• Licensed release. Possums cannot be released more than 50 metres from the capture site in most states. Professionals know the legal release requirements and handle the relocation lawfully.
• Legal proofing. After removal, the operator seals all entry points of 50 mm or larger using durable materials that comply with building codes and wildlife regulations. Professional possum proofing is designed to last, not just block the obvious hole.
• Warranty. Good operators stand behind their proofing work with a warranty. If the possum gets back in, they come back and fix it at no extra cost.

The full process — inspection, humane removal, legal proofing — is what makes professional possum removal the only real solution that lasts. Anything else is a temporary fix that costs more in the long run.

How Fast Can a Possum Cause Damage?

Possums cause damage faster than most people expect. Within the first week of taking up residence in your roof, a possum can:

• Soak insulation with urine, reducing its thermal performance
• Leave droppings that attract insects and create health risks
• Gnaw on electrical wiring, creating a fire hazard
• Damage ductwork and air conditioning pipes
• Scratch and gouge timber beams during territory marking

The longer a possum stays, the more expensive the repairs. A possum that has been in the roof for months can cause thousands of dollars in damage to insulation, wiring, and structural timber. That is why early action matters — the sooner you confirm the signs and call a professional, the less damage you will be dealing with.

If you are also hearing noises at night, our guide on possum noises at night can help you distinguish between possums, rats, and other roof pests.

Frequently Asked Questions

How do I know if I have a possum or a rat?

Weight is the difference. A rat weighs 100–500 grams and makes fast, light skittering sounds. A brushtail possum weighs 1.5–4.5 kilograms and makes heavy, deliberate thumping sounds like a small human walking. Possums also produce a strong ammonia smell, leave larger droppings (1–2 cm), and are most active between 9pm and 4am.

Is it illegal to remove a possum yourself?

Yes. Possums are protected native wildlife in Australia. Trapping, handling, or removing one yourself without a licence is illegal in every state. Penalties range from $5,000 in South Australia to $25,740 in Queensland. A licensed possum removal operator must handle the job lawfully.

How fast can a possum cause damage?

Within the first week a possum can soak insulation with urine, leave droppings that attract insects, gnaw on electrical wiring creating a fire hazard, and damage ductwork. Over months, the damage can run into thousands of dollars in repairs to insulation, wiring, and structural timber.