A possum box should be installed at a minimum height of 4 metres — ideally 5–6 metres — facing north to north-east, within 150 metres of the capture site, with the resident possum's own nesting material placed inside to trigger territorial recognition.

Possum boxes — also called possum homes or nest boxes — are an essential part of humane possum management in Australia. When a possum is removed from a roof cavity, a properly installed possum box gives the displaced animal a legal, safe alternative den. In some states, installing one is a legal requirement after removal.

But a possum box only works if it is built to the right specifications and installed in the right location. A box nailed to a tree at head height with the wrong entrance hole will sit empty for years. This guide covers the exact specifications, installation process, and maintenance required to make a possum box actually work. For a review of commercial options, see our Bunnings possum box review.

Why Possum Boxes Work

Possums are territorial. A possum that has been living in a roof cavity will seek out a new den in the same area after removal. If a properly constructed possum box is available nearby, the possum will often take up residence in it rather than trying to re-enter the roof or find a new house to invade.

The key is territorial recognition. By placing the possum's own nesting material inside the box — collected from the roof cavity during removal — the box smells familiar and triggers the possum's territorial instinct. It sees the box as an extension of its existing territory, not a new and unfamiliar environment.

This is why possum boxes installed without scent conditioning often fail. The box smells like pine, plywood, or whatever it was made from. A possum will not willingly move into a box that smells like a hardware store.

Possum Box Specifications

Getting the specifications right is the difference between a box that gets used and a box that gathers cobwebs.

Height

Minimum 4 metres above ground. Ideal height is 5–6 metres. This puts the box above the line of sight of predators like dogs and cats and mimics the height of a natural tree hollow. Boxes installed at 1–2 metres — which is where most DIY installations end up — are rarely accepted by possums.

Direction

Face the entrance north to north-east. This protects the possum from prevailing cold winds and allows morning sun to warm the box. A south-facing box stays cold and damp, which possums avoid.

Entrance Size

Entrance size depends on the target species. Brushtail possums need a 120 mm diameter entrance. Ringtail possums need 70 mm. A 70 mm entrance will exclude brushtails entirely. This is the most common mistake in commercial possum boxes — many are built to ringtail spec, which means they only work for one species.

Material

Untreated marine plywood or hardwood timber. Treated pine is toxic to possums and should never be used. The wood should be at least 20 mm thick for insulation and durability. Internal surfaces should be rough-cut rather than sanded smooth so possums can grip the walls when climbing in and out.

Internal Dimensions

Brushtail box: minimum 300 mm wide x 300 mm deep x 400 mm high. Ringtail box: slightly smaller at 250 mm wide x 250 mm deep x 350 mm high. Both need a sloping roof to shed rain and ventilation gaps near the top to prevent overheating in summer months.

Possum Box Installation Guide

Installing a possum box correctly is as important as building it right. Here is the step-by-step process professional operators use.

1. Select the tree. Choose a mature tree with a trunk diameter of at least 300 mm at chest height. The tree should be within 150 metres of the capture site — any further and the possum may not find it. Native eucalypts are ideal.
2. Determine the height. Mark the trunk at 5–6 metres above ground level. Use a ladder or telescopic pole to reach the installation point safely.
3. Attach a mounting bracket. Use galvanised or stainless steel brackets that will not rust. Wrap the bracket around the trunk with the box fastened to it. Do not nail or screw directly into the tree — this can damage the tree and introduce infection.
4. Orient the entrance. Rotate the box so the entrance faces north to north-east before tightening the bracket. Check the direction with a compass app on your phone.
5. Add nesting material. Place the possum's own nesting material from the roof cavity inside the box. If that is not available, use dried native leaves and shredded paperbark — not hay or straw, which can harbour mould.
6. Secure against predators. Ensure the bracket is tight enough that a possum cannot shake the box loose. Add a predator guard — a smooth metal collar — below the box if the area has goannas or large snakes.

Possum Box Maintenance

A possum box requires minimal maintenance but should be checked annually.

• Inspect the bracket and fixings for rust or loosening
• Check the roof for leaks — replace if the timber has warped or cracked
• Remove any wasp nests or spider webs from the entrance
• Replace nesting material if it has become damp or mouldy
• Check that the entrance hole has not been enlarged by cockatoos or other wildlife

If a possum box stays empty for more than 12 months, check the height and direction. Most empty boxes are either too low or facing the wrong way. Professional possum box installation services can assess the location and adjust the placement if needed.

Possum boxes should not be installed while a possum is still inside the roof. Always remove the possum lawfully first, then install the box after. For homeowners in Sydney, licensed possum removal operators can coordinate both removal and box installation as part of a single service.

Frequently Asked Questions

What height should a possum box be installed?

A possum box should be installed at a minimum height of 4 metres, ideally 5–6 metres above ground. Boxes installed lower than 4 metres are rarely accepted by possums because they feel vulnerable to predators at ground level.

What direction should a possum box face?

The entrance should face north to north-east. This protects the possum from prevailing cold winds and allows morning sun to warm the box. South-facing boxes stay cold and damp and are usually rejected.

Do I need a licence to install a possum box?

Installing a possum box itself does not require a licence in most states. However, the possum removal that precedes it does. Possum boxes should only be installed after a licensed operator has humanely removed the possum from the roof.

Should I buy or build a possum box?

Commercial possum boxes like the ones sold at Bunnings work for ringtail possums but often fail for brushtails due to the 70 mm entrance. Professional-grade boxes are built to the correct species-specific specifications and installed at the right height by experienced operators.