How to Keep Possums Out of Your Roof in Melbourne

Why Possums Love Melbourne Roofs

Common brushtail possums (Trichosurus vulpecula) are native to Australia and protected under the Wildlife Act 1975 (Vic). They’re highly territorial, returning to the same den night after night. Melbourne’s older housing stock — particularly timber-framed homes built before 1980 in suburbs like Dandenong, Narre Warren, and Frankston — gives possums exactly what they’re looking for: dark, warm, dry voids accessed through gaps in fascias, soffits, and valleys.

Brushtail possums are solitary and nocturnal. If you hear thumping, scratching, or hissing from your roof cavity between dusk and dawn, there’s almost certainly one living up there. A single possum can cause significant damage: urine soaks insulation and ceiling plasterboard, droppings accumulate, and their gnawing on timbers and electrical cables is a fire risk.

Step 1: Confirm the Entry Points

Before you can exclude a possum, you need to know where it’s getting in. Do this at dusk, when the possum leaves to forage. Stand back from the house and watch the roofline carefully — you’re looking for movement coming out from a specific gap. Then, with a torch, check these common entry points:

• Gaps between fascia boards and roofing — especially where fascia has warped or pulled away from the roof edge
• Broken or missing soffit panels — common on homes with timber weatherboard construction
• Valley junctions — where two roof sections meet, there is often a void large enough for a possum
• Gaps around pipe penetrations — plumbing vents, gas pipes, and TV antenna cables often have poorly sealed entry points
• Ridge capping cracks — cracked mortar along the ridge lets possums squeeze under lifted tiles

Step 2: Install a One-Way Door (Let It Out, Not In)

The key principle of possum exclusion is that you must give the possum a way to leave before you permanently seal the entry. If you seal it in, it will panic, tear through your ceiling, or die in the roof — all far worse outcomes.

A possum one-way door (sometimes called an excluder flap) is a simple hinged or spring-loaded flap that lets the possum push out but not re-enter. You can buy a plastic or wire mesh excluder from your local hardware store for around $15–$30, or improvise one from heavy-gauge mesh and a piece of timber.

1. Identify the primary entry point (there’s usually one main hole, with secondary smaller gaps nearby)
2. Install the one-way door over the main entry point at dusk before the possum leaves
3. Leave it in place for 3–5 nights minimum to ensure the possum has exited
4. Check that no young joey is left inside before sealing permanently (spring–summer, females carry joeys)
5. Remove the one-way door and seal the gap permanently (see Step 3)

Step 3: Permanently Seal All Entry Points

Possums can gnaw through soft materials — foam, silicone, and wood filler won’t last. Use galvanised steel mesh (hardware cloth, 19-gauge or heavier) cut to size and secured with roofing screws or staples. For larger gaps and soffit voids, use colorbond sheet metal or fibre-cement sheet fixed with self-tapping screws.

• Small gaps (<50mm): 19-gauge galvanised mesh, stapled and folded into the gap, or exterior-grade silicone over solid backing
• Larger gaps (50–200mm): Galvanised mesh framed with treated pine batten, screwed to fascia
• Broken soffit panels: Replace with fibre-cement sheeting cut to size (Villaboard or James Hardie)
• Ridge capping cracks: Re-bed and repoint cracked mortar; a licensed roof tiler does this for $200–$500

Step 4: Provide an Alternative Den Box

Under Victorian law, it’s illegal to permanently displace a possum without providing an alternative shelter in the same territory. A possum nesting box, installed in a nearby mature tree at least 4 metres off the ground, gives the possum somewhere to go and significantly reduces the chance it will try to re-enter your roof.

Possum boxes are available from Bunnings and Mitre 10 for around $40–$80, or you can build one from untreated hardwood. The entry hole should be 120mm in diameter for brushtail possums, or 80mm for ringtail possums. Face the box east or north-east, in shade, and use untreated wood shavings as bedding material.

Troubleshooting Table

When to Call a Licensed Wildlife Controller

You can legally trap and release a possum yourself in Victoria, but only within 50 metres of the capture point. If you can’t safely access your roof, if the possum is in a wall cavity, or if you have a joey situation, call a licensed wildlife controller or pest inspector. In Melbourne’s south-east, licenced controllers typically charge $250–$600 for exclusion work including sealing.

Contact Wildlife Victoria for referrals to licensed handlers. Do not use a pest controller who advertises possum removal — they are legally required to release within 50 metres and cannot relocate possums to distant bushland.

Tips and Gotchas

1. Never seal during breeding season without checking for joeys. In Victoria, brushtail possums breed August–November. A joey in the pouch cannot survive without its mother.
2. Napthalene (mothballs) and ammonia don’t work. Possums habituate to chemical deterrents within days. Exclusion is the only reliable fix.
3. Ultrasonic devices are ineffective. Multiple studies confirm possums don’t respond to ultrasonic frequency deterrents — save your money.
4. Check your neighbour’s tree, not just yours. If overhanging branches belong to a neighbouring property, you’ll need a polite conversation before trimming.
5. Roof void urine smell can persist for months. Replace soaked insulation and use an enzyme-based odour eliminator (available from Bunnings, ~$15) before re-insulating.
6. Possums are aggressive when cornered. They have sharp claws and teeth. Never try to manually remove one from a roof space — use the one-way door method.
7. Check your home insurance. Possum damage is sometimes covered under contents or building insurance if the animal was an uninvited pest — worth a call to your insurer.
8. Mesh gauge matters. Standard fly-screen mesh is too thin — possums can chew through it. Use 19-gauge galvanised hardware cloth (also called aviary wire).

Local Melbourne Resources

• Wildlife Victoria — 24-hour wildlife emergency line (1300 094 535), licensed handler referrals
• Bunnings — 19-gauge galvanised hardware cloth and possum nesting boxes
• Mitre 10 — hardware mesh, tin snips, roofing screws
• Agriculture Victoria — information on possum management and legal obligations
• Local council wildlife officers — many SE Melbourne councils (Casey, Frankston, Mornington Peninsula) have wildlife advice lines

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