Possums on Your Roof: Damage They Cause and How to Stop Them

6 min read

If you’re hearing heavy thumping on your roof at night, scratching in the ceiling, or finding displaced tiles in the morning, you’ve probably got a possum problem. Perth’s brushtail possums are prolific, territorial, and very good at finding their way into roof cavities.

They’re a protected native species - you can’t harm or relocate them without a licence - but you absolutely need to manage them, because the damage they do to roofs is significant and ongoing.

The Damage Possums Cause

Displaced and Broken Tiles

Possums are strong for their size and remarkably persistent. They lift, shift, and break roof tiles to create entry points into the cavity. A single possum will establish a preferred entry and exit route, displacing the same tiles repeatedly.

Every displaced tile is a leak waiting to happen. Even if the possum only lifts the tile slightly, rain can penetrate the gap - especially during Perth’s winter storms with wind-driven rain.

Urine and Droppings

Possum urine is corrosive and leaves persistent stains. Inside the roof cavity, urine soaks into timber framing, insulation, and ceiling plasterboard. Over time, this causes:

• Brown stains on ceilings that bleed through paint
• Odour that’s difficult to eliminate
• Degradation of timber surfaces
• Insulation contamination that reduces effectiveness

The smell alone drives many homeowners to action, but the structural damage from years of urine exposure is the bigger concern.

Insulation Destruction

Possums nest in insulation batts, pulling them apart, compressing them, and contaminating them. Once a possum has been living in your insulation, it needs replacing - it’s compressed (no longer insulating effectively), contaminated with urine and droppings, and often scattered across the cavity instead of sitting neatly between joists.

Electrical Wiring

Possums gnaw on electrical wiring in the cavity. This is a genuine fire hazard. Exposed wires in a cavity full of dry insulation and timber is a dangerous combination. If you suspect possum activity in your roof, having an electrician check the wiring afterward is sensible.

Pointing and Flashing Damage

Possums scratch and push at pointing compound and flashings to widen gaps. Fresh flexible pointing is particularly vulnerable - it’s soft enough for a determined possum to dig through. We occasionally see roofs where recently repointed ridge caps have been damaged within months by possum activity.

Identifying Possum Entry Points

Common entry points on Perth roofs:

• Broken or displaced tiles - the most obvious sign
• Gaps at the ridge line - where ridge caps meet tiles, especially if pointing has failed
• Eave gaps - where the roof meets the soffit, particularly if timber has warped or been damaged
• Around roof penetrations - gaps around vent pipes, aerial mounts, or solar panel conduits
• Valley areas - where two roof planes meet, gaps can develop as the structure settles

From inside the cavity (daylight inspection), look for:

• Droppings - possum droppings are dark, pellet-shaped, and about 1-2cm long
• Nesting material - shredded insulation, leaves, bark
• Scratch marks on timber
• Urine stains (dark patches on timber, particularly along travel routes)
• Daylight visible through entry points

Legal Requirements in WA

Brushtail possums are protected under the Biodiversity Conservation Act 2016. You cannot:

• Kill, poison, or injure them
• Relocate them more than 25 metres from where they’re caught
• Disturb their habitat without appropriate approvals

You can:

• Install one-way exits that let them leave but not return
• Block entry points once you’ve confirmed the possum has left
• Install possum boxes on nearby trees as alternative shelter
• Engage a licensed pest controller for humane management

The Department of Biodiversity, Conservation and Attractions (DBCA) issues licences for possum management. In most cases, a licensed pest controller handles this on your behalf.

How to Possum-Proof Your Roof

Step 1: Identify All Entry Points

This requires a thorough roof inspection - both external (tile displacement, pointing gaps, eave damage) and internal (daylight test, droppings, damage patterns).

Every entry point needs to be found. Block most but leave one - that becomes the one-way exit point.

Step 2: Install a One-Way Exit

A one-way possum door or flap allows the possum to leave at night (they’re nocturnal and leave to feed) but prevents re-entry. This needs to stay in place for at least a week to ensure the possum has left - they sometimes skip a night.

Step 3: Seal All Entry Points

Once you’re confident the cavity is empty (check for remaining droppings or noise over several nights), seal everything:

• Replace broken tiles and ensure all tiles are properly seated
• Repoint ridge capping with flexible pointing compound
• Seal eave gaps with galvanised mesh or purpose-made possum guards
• Block gaps around penetrations with appropriate sealant or mesh
• Repair flashings that have been pushed open

The sealing needs to be thorough. Possums are persistent and will test every potential entry point for weeks after being excluded. A single missed gap and they’re back in.

Step 4: Provide an Alternative Home

Installing a possum nesting box on a nearby tree gives the evicted possum somewhere to go. They’re territorial - they won’t just move to another suburb. Without an alternative shelter, they’ll work harder to get back into your roof.

Possum boxes are inexpensive ($50-$100) and surprisingly effective. Mount them 3-4 metres up a tree, facing away from prevailing weather, with a clear flight path.

How Roof Restoration Helps

A full roof restoration is one of the most effective possum-proofing measures because it addresses all the common entry points in one go:

• All ridge capping is rebedded and repointed, sealing the ridge line
• Broken and cracked tiles are replaced
• Flashings are repaired and resealed
• Any gaps around penetrations are sealed

After a restoration, the roof is essentially sealed. Combined with possum exclusion at the eaves (which we can install during the work), there are no entry points left.

If you’re planning a restoration and also have a possum problem, coordinate the timing - have the pest controller exclude the possums first, then restore the roof to seal everything permanently.

The Bottom Line

Possums are a fact of life in Perth suburbs, and they cause genuine damage to roofs, insulation, and wiring. The solution is humane exclusion followed by thorough sealing of all entry points.

Trying to live with possums in your roof cavity - hoping they’ll move on - is a losing strategy. They’re territorial, they breed, and the damage accumulates every month they’re in there. The sooner you address it, the less remediation you’ll need afterward. Once the possums are out, a roof repair for the broken tiles, or a full roof restoration to seal the whole roof, keeps them out for good. Get a free quote and we’ll take a look.