Quick Answer
Mice and rats enter Melbourne homes through gaps as small as 6mm (mice) or 20mm (rats) — typically around pipes, cables, roof joins, subfloor vents and garage doors. The most effective approach is exclusion first: seal every entry point with steel wool, expanding foam and metal flashing, then set traps inside. A full DIY exclusion project costs $50–$150 in materials; professional pest control runs $150–$350 for a treatment visit.
How Rodents Get In: Common Entry Points in Melbourne Homes
Melbourne’s south-east suburbs have a mix of housing stock — 1970s–90s brick veneer homes in Narre Warren, Berwick and Cranbourne, and older weatherboard homes in Frankston, Mornington and Officer. Each type has characteristic weak points.
| Entry Point | Where to Check | Common In |
|---|---|---|
| Pipe and cable penetrations | Exterior wall base, laundry, kitchen | All homes |
| Subfloor vents (damaged or missing mesh) | Perimeter foundation vents | Older weatherboard homes |
| Roof joins and fascia gaps | Where roof meets wall, fascia ends | Tiled roofs, brick veneer |
| Garage door seal (bottom) | Bottom of roller or panel door | All homes with garage |
| Weep holes in brick veneer | Low mortar courses on exterior | Brick veneer (post-1960) |
| Under eaves (open cavities) | Soffit joins, air vent covers | Older homes with open eaves |
| Damaged or missing roof tiles | Roof perimeter, valley joins | Tiled roof homes |
Sealing Entry Points: Materials and Methods
Steel Wool and Expanding Foam (Pipe Gaps)
Pack steel wool tightly into gaps around pipes and cables — rodents cannot chew through it. Follow with a layer of expanding foam sealant (Sika, Selley’s or Great Stuff) to lock the steel wool in place and fill the surrounding cavity. Steel wool alone will compress and shift over time; foam alone can be chewed through. Combined, they are highly effective.
Metal Flashing and Mesh
For subfloor vent openings with damaged or rusted mesh, replace with galvanised steel mesh (6mm grid for rats, 3mm for mice). Cut to fit with tin snips and secure with galvanised screws. Flashing-grade aluminium sheet (from Bunnings roofing section) can cover larger gaps at eaves or fascia joins.
Door and Garage Seals
Replace worn rubber seals under external doors and garage doors. Mice need only a 6mm gap — if you can slide a pencil under your garage door, mice can enter. Rubber bottom seals for roller doors cost $20–$40 per metre from roller door suppliers or Bunnings. For external doors, a quality aluminium door seal with a heavy rubber blade is more durable than self-adhesive foam tape.
Weep Holes
Weep holes in brick veneer walls are an important moisture management feature — do not permanently seal them. Use purpose-made plastic weep hole covers (Bunnings, $8–$15 for a pack) that allow air and moisture movement but exclude rodents. Do not use foam, mortar or tape to seal weep holes.
Trapping: What Works in Melbourne Homes
| Trap Type | Best For | Cost | Notes |
|---|---|---|---|
| Snap traps (Victor, Goodnature) | Mice and rats inside roof/walls | $5–$25 each | Most effective; check daily |
| Electric traps (Goodnature A24) | Ongoing rat control outdoors | $150–$200 | CO2-powered; long-lasting bait |
| Live catch traps | When pets/children at risk | $20–$50 | Check every 4–6 hours; relocate 2km+ |
| Bait stations (licensed rodenticide) | Heavy infestations | $30–$80 station + bait | Use tamper-resistant stations; risk to pets |
Signs of Active Infestation
| Sign | What It Indicates | Action |
|---|---|---|
| Droppings (dark, pointed, 6–12mm) | Active mice or rats; size indicates species | Identify species, set traps in same area |
| Gnaw marks on cables, timber, food packaging | Active feeding | Remove food sources; set traps nearby |
| Scratching sounds in roof at night | Rodents in roof cavity | Roof snap traps; check roof entry points |
| Strong ammonia smell | Urine from active colony | Seal entry, trap, professional clean if severe |
| Nesting material (shredded paper, insulation) | Established nest nearby | Locate nest area, increase trap density |
When to Call a Licensed Pest Controller
Call a professional when: the infestation is large or well-established, you are hearing rodents in wall cavities (which are very difficult to treat DIY), when there is evidence of gnawed electrical cables (a fire risk requiring immediate attention), or when previous DIY attempts have not resolved the problem after 2–3 weeks. A professional treatment in SE Melbourne costs $150–$350 for a visit; ongoing contracts $60–$120 per month. Ensure the pest controller is licensed with Victorian EPA.
Top 8 Tips and Gotchas
- Exclusion before trapping — trapping without exclusion is a treadmill. New rodents move in as you remove others. Seal every entry point first, then trap the remaining interior population.
- Remove food sources — pet food, compost, fallen fruit and bird feeders are primary attractants. Store pet food in sealed metal containers, manage compost correctly, and pick up fallen fruit from trees.
- Roof cavity is priority — rodents in roof cavities chew electrical cables, wiring and insulation. If you hear scratching above your ceiling, this needs urgent attention before electrical damage occurs.
- Peanut butter beats cheese — snap traps baited with peanut butter, Nutella or nesting material (cotton wool) are far more effective than cheese in Australian conditions.
- Check subfloor after rain — Melbourne winter rains drive rodents out of the garden and into dry subfloor spaces. Check and clear subfloor vents after heavy rain events.
- Glue boards are inhumane — avoid adhesive glue traps. They cause prolonged suffering and are increasingly considered unacceptable. Snap traps are quick and more effective.
- Neighbourhood awareness — rodents range over 30–50 metres. If your neighbours are attracting rodents (cluttered gardens, open compost, outdoor pet food), coordinate exclusion and trapping efforts if possible.
- Check around the gas meter — the cavity around gas meter boxes on exterior walls is a common and overlooked rodent entry point. Seal with steel wool and foam.
Frequently Asked Questions
How do I know if I have mice or rats?
Rat droppings are 12–20mm long, dark brown and blunt-ended. Mouse droppings are 3–6mm, pointed at both ends. Rats are also louder and more destructive — you’ll hear heavier thumping in the roof versus the scurrying scratch of mice. Rats need a 20mm gap to enter; mice only 6mm.
Can I use poison bait myself in Victoria?
Most rodenticide baits are available at hardware stores for consumer use. However, second-generation anticoagulants (the most effective ones) carry significant risk to native wildlife and pets. In SE Melbourne’s wildlife corridors (near Dandenong Ranges, Mornington Peninsula, Cranbourne nature reserves), snap traps are strongly preferred. If using bait, use only in locked tamper-resistant stations.
How do I get rid of mice in my roof?
Set snap traps baited with peanut butter along roof cavity beams and at the entry point. Place traps perpendicular to the beam with the trigger end facing the wall — mice run along edges. Check and re-bait every 2–3 days. Once activity stops, seal all entry points and remove traps. Leaving unbaited traps permanently can actually train rodents to avoid the area and then return when traps are gone.
Are weep holes in brick veneer homes a mouse entry point?
Yes — standard 65mm wide weep holes are large enough for mice. Install purpose-made plastic weep hole inserts (Weep-Eze or similar) that allow moisture movement but exclude rodents. Do not permanently seal or mortar weep holes — they are essential for moisture control in brick veneer walls.
Melbourne Local Resources
- Bunnings — snap traps, live traps, bait stations, steel wool, expanding foam
- Mitre 10 — galvanised mesh, metal flashing, door seals
- Goodnature — A24 CO2-powered humane rat traps (no bait risk to native wildlife)
- Victorian EPA — licensed pest controller directory for SE Melbourne