How to find where mice are coming into the house

"I think I’ve spotted a mouse, where are the best places to check for signs and how might I find where they are getting in?"

Mice don't need much of an opening to get inside. A house mouse can squeeze through a gap as small as a dime, or roughly ¼ of an inch. That means even a home that looks well-sealed can have entry points you'd never notice at a glance.

They follow warmth, food smells, and the path of least resistance. Here are the most common entry points:

• Gaps around pipes and utility lines: Where plumbing, gas lines, or cables pass through walls, there's often a small gap that's never been properly sealed.
• Cracks in the foundation: Even hairline cracks can widen over time, giving mice a way in at ground level.
• Gaps under doors: Exterior doors without a proper door sweep, especially garage doors, are a common entry point.
• Vents and weep holes: Unscreened vents, soffit openings, and weep holes in brick walls are easy access points.
• Roof and eave gaps: Roof rats and mice can climb, so gaps where the roofline meets the wall matter too.
• Damaged weatherstripping: Worn or missing seals around doors and windows leave gaps that are easy to miss.

How to find where mice are getting in

Tracking down entry points takes a methodical approach, and it's harder than it sounds. Here are a few things to look for:

• Follow the signs: Droppings, grease marks along baseboards, and gnaw marks near walls often indicate the route mice are taking. Start there and work outward.
• Check low and high: Entry points can be at ground level (foundation cracks, door gaps) or up high (roof vents, eave gaps).
• Look for daylight: In a dark basement or crawl space, gaps that let in light also let in mice.
• Feel for drafts: Cold air entering a wall cavity often indicates an unsealed opening.
   

Even with a thorough search, entry points can be easy to miss, especially in older homes with settled foundations or complex rooflines. Our rodent exclusion services include a full property inspection to identify exactly where mice are getting in, followed by targeted sealing using durable Flexi Armour products designed to keep them out.