How do mice get in the house?
Where Do Mice Get Into the House? Common Entry Points and How to Find Them.
Mice can squeeze through incredibly small openings—as tiny as 1/4 inch (about the size of a dime)—to enter homes. They seek warmth, food, and shelter, especially in fall and winter. Understanding the most common entry points helps you seal them off before an infestation grows. Top Common Entry Points for Mice Here are the most frequently reported ways mice enter homes, based on pest control experts and homeowner experiences:
1. Gaps and cracks in the foundation or exterior walls
Mice exploit settling cracks, gaps where siding meets the foundation, or openings at corners where materials don't join perfectly.
2. Around doors and windows
Worn weatherstripping, gaps under exterior doors (including garage doors), or poorly sealed window frames allow easy access.
3. Openings for utilities (pipes, wires, cables)
Gaps around plumbing lines, electrical wiring, gas lines, AC compressor lines, or dryer vents are prime entry routes—mice chew through weak seals.
4. Vents and foundation openings
Foundation vents, attic vents, chimney gaps, or unscreened crawl space vents provide direct access, especially if screens are damaged.
5. Under porches, stoops, decks, or steps
Settling concrete creates gaps where rebar or supports meet the house, giving mice a path up and in.
6. Rooflines, eaves, and soffits
Damaged roofing, gaps in soffit vents, or openings where roof meets walls let mice enter attics, then move down into living spaces.
7. Sump pumps, drains, or sewer lines
In some homes, mice travel through drain tiles or sump pits if covers are loose.
8. Garage and shed connections
Gaps under garage doors or where attached garages meet the main house are overlooked entry points.
Mice rarely create new holes—they use existing ones and enlarge them by chewing if needed. How to Find Where Mice Are Getting In? Spotting entry points isn't always obvious. Use these practical steps:
1. Inspect during daylight — Go outside and look for light leaking into attics/basements from exterior gaps.
2. Look for signs — Mouse droppings (small, dark, rice-shaped), gnaw marks, rub marks (greasy trails along walls), or urine stains (visible under UV/black light).
3. Use tracking powder — Sprinkle flour or baby powder along baseboards/walls; mouse footprints reveal paths to entry points.
4. Check high-risk areas first — Start with utility penetrations, doors/windows, foundation cracks, and vents.
5. Listen and smell — Scratching noises in walls/attics or a musky odor can point to active routes.
Prevention and Control: When to DIY vs. Call a Professional While you can start with sealing small gaps yourself (using steel wool packed tightly then covered with caulk or expanding foam—mice can't chew through steel wool easily), calling a professional pest control service is often the best solution for a comprehensive, long-term plan.
Professionals conduct thorough inspections (interior and exterior), identify hidden entry points and nesting areas you might miss, assess the full extent of the infestation, and create a customized strategy that combines exclusion, trapping, sanitation, and safe baiting. This integrated approach eliminates the current problem and prevents recurrence far more effectively than piecemeal DIY efforts, especially in moderate to severe cases or homes with pets/children.
Rodenticides (rodent baits/poisons) can be an important tool. Placing tamper-resistant bait stations around the exterior within guidelines helps control mice before they find or chew new gaps into your house. Professionals handle placement safely and legally. Always follow product labels strictly, and never use rodenticides without secure, tamper-resistant stations. Quick Prevention Tips
a. Seal any hole larger than 1/4 inch with steel wool + caulk/foam.
b. Install door sweeps, repair screens, and trim vegetation away from the foundation.
c. Keep food sealed and clean up crumbs to remove attractants.
d. For ongoing protection, consider professional perimeter treatments with bait stations.
Mice enter through surprisingly small gaps—focus on sealing and prevention. If signs persist after initial efforts, or if you're dealing with droppings in multiple areas, a professional provides the most reliable path to a rodent-free home.