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Entry pointsModerate risk

How Are Mice Getting Into My House?

Written by PestMan Editorial TeamTechnical review pendingPublished Updated

Quick answer

Mice can squeeze through gaps of about 6 mm, roughly the width of a pencil. Common routes are gaps around pipes under sinks and behind appliances, under doors and garage doors, weep holes, vents and gaps where cables and air-conditioning lines enter walls. They also come in with stored boxes, firewood and animal feed.

Why this happens

Mice have flexible skeletons and can compress their bodies to fit through any gap their head can pass through.

Cooler weather in autumn and winter, food shortages outside and disturbances such as harvests or building work nearby all push mice into homes.

What you may be seeing

  • Droppings in kitchen drawers, pantry shelves and under sinks.
  • Chewed packaging.
  • Scratching in walls or cupboards at night.

What you can do

  • Inspect under sinks, behind the fridge, dishwasher and washing machine for pipe gaps.
  • Pack gaps with steel wool or stainless mesh and seal with a suitable sealant.
  • Fit brush strips or door sweeps to external and garage doors.
  • Use weep-hole covers designed to keep rodents out while allowing ventilation.
  • Store food in hard sealed containers.
  • Use snap traps along walls where droppings are found.

What not to do

  • Do not block weep holes or vents completely.
  • Do not use expanding foam alone; mice chew through it.
Using pest products safely

Rodenticides must be used exactly as the label directs, in tamper-resistant bait stations where required, and out of reach of children, pets and wildlife. Dead rodents should be removed with gloves. If a child or pet may have eaten bait, call the Poisons Information Centre (13 11 26) or your vet immediately.

When professional help may be needed

If you keep catching mice after sealing obvious gaps, a professional can find less obvious entry points such as roof and wall-cavity access.

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Sources & further reading

PestMan provides general information only and does not replace licensed pest-management, medical, veterinary or structural advice. Always read and follow product labels. Read our disclaimer.