Brushtail possums in a roof space are common right across Sydney, and especially so in the leafy suburbs — the North Shore, the bushland fringes, anywhere with mature canopy against the roofline.
The noise is what people notice. The mess is what costs money.
The legal position first
Brushtail and ringtail possums are protected native wildlife in NSW. You cannot kill them, you cannot relocate them, and trapping requires a licence from NPWS.
A licensed operator may trap a possum and must release it on the same property, within 50 metres, on the same night. Relocating it elsewhere is illegal, and it is also pointless — a displaced possum dies and another moves into the vacant territory within days.
So the actual solution is never removal. It is exclusion: get the animal out, seal every entry point, and provide a nest box so it has somewhere else to be.
Timing matters. A female with dependent young in the pouch or on her back must not be excluded, because sealing the roof separates her from the nest and the young die inside the cavity. Spring and autumn are the main breeding periods. Anyone willing to seal your roof without checking this is not someone to use.
What the damage actually is
Urine and droppings. The main cost. Possum urine soaks into insulation, ceiling plaster and timber, and the smell is persistent and penetrating. Ceiling stains come through eventually. Saturated insulation loses its R-value and has to be replaced.
Nesting material in the gutters. Leaves, bark and debris dragged in and pushed out, ending up in gutters and valleys and blocking downpipes. This is where the roof problem becomes a water problem — see why gutters overflow and blocked downpipes.
Displaced and broken tiles. Possums push tiles aside to get in and out. A lifted tile is a leak, and a cracked one is a leak you find during the next storm.
Chewed cabling. Less common than with rodents but it happens, and it is a fire risk.
Damaged sarking, torn where they move across it.
Fleas and mites, which stay in the roof space after the possum has gone and come down into the house.
If the roof feeds a rainwater tank
This is the part that needs taking seriously.
Possum droppings and urine on a catchment roof go into the tank. Possums can carry organisms that affect water quality, and the contamination is not theoretical — it washes in with the next rain.
If you have an active possum problem and a connected tank, disconnect the tank now, before any cleaning starts, and keep it disconnected until the roof has been cleaned and had a good rain through it. Depending on how long the problem has been running, the tank itself may need desludging — see cleaning a rainwater tank and roof cleaning on tank-fed properties.
How they get in
A brushtail needs a surprisingly small gap. Common entry points:
- Broken or displaced roof tiles
- Gaps where the roof meets the fascia or the barge board
- Unscreened eave and gable vents
- Gaps around pipe and flue penetrations
- Lifted ridge capping
- Open valleys where two roof sections meet
Access is usually from an overhanging branch. Cutting back limbs within about two metres of the roofline is the most effective single measure, and it also reduces the leaf load in your gutters.
The order of work
- Confirm what you have. Possums are heavy and move at dusk and dawn with a distinct thump. Rats are lighter, faster and active through the night. The treatment is completely different.
- Check for dependent young before anything is sealed.
- Exclude — one-way door, let the animal leave, then seal. Install a nest box first so it has an alternative.
- Seal every entry point. Missing one makes the whole exercise pointless.
- Clear the roof space — droppings, nesting material, contaminated insulation.
- Clean and sanitise, including the gutters and the roof surface.
- Repair broken tiles and sarking.
- Cut back the branches, or they will be back.
Where we come in
We do not trap or exclude possums — that is a licensed wildlife operator’s job, and on a job like this the sequencing matters more than the cleaning.
What we do is the aftermath: gutters cleared and downpipes flow-tested, roof surface cleaned and decontaminated, solar panels cleaned if they are fouled, and the catchment made safe again if there is a tank. See gutter cleaning and roof cleaning.
Do the exclusion first. Cleaning a roof that still has a possum living in it is work you will be paying for twice.
The equivalent problem with birds under a solar array is covered in bird proofing solar panels.
