A mouse can squeeze through an opening about the width of a dime, while rats need only a gap roughly the size of a quarter. That makes a quick look around your home worthwhile, especially near places where building materials meet or pipes and wires pass through walls. Check from the ground up, look for signs of wear or gnawing, and note any gaps you cannot safely reach. Finding openings early gives you a chance to seal them before rodents move indoors.
Start at the foundation
Walk around the outside of your home and inspect where the siding meets the foundation. Look for cracks, holes, loose siding, and gaps around basement windows. Pay attention to corners and areas hidden behind shrubs, stored items, or outdoor equipment. Move obstructions carefully so you can see the wall, and check whether soil or mulch has built up against the siding.
Look for evidence that an opening is being used, such as droppings, tracks in dust, gnaw marks, or a worn path along the wall. A hole may also contain nesting material. Do not assume a small gap is harmless: rodents can enlarge some openings by gnawing. Photograph anything you find and note its location so you can track changes or show it to a professional.
Check rooflines and upper walls
From the ground, scan eaves, soffits, fascia boards, roof edges, and the places where different roof sections meet. Look for missing or damaged materials, loose trim, and gaps beneath roof edges. Use binoculars if needed rather than climbing onto a roof. Also inspect around attic vents and gable ends, where damaged screens or loose covers can leave a route inside.
Tree branches and vines that touch the roof or exterior walls can make it easier for rodents to reach upper openings. Trim vegetation back where practical, and keep climbing plants from covering siding or vents. If you see damage high above the ground, avoid reaching it with an unstable ladder; a qualified professional can inspect and repair hard-to-access areas safely.
Inspect utility lines and openings
Where plumbing, electrical conduit, cable, or gas lines enter the house, check for space between the pipe or wire and the surrounding wall. Inspect outdoor faucets, air-conditioning lines, and connections near the basement or utility room, too. Look for cracked sealant, missing covers, or holes that leave daylight visible. Never pull on wiring or disturb gas equipment while inspecting.
Check dryer, bathroom, and kitchen exhaust vents for secure covers and intact screens designed for the vent. The cover should open and close as intended, without a visible gap around its edges. Do not block a vent or use a screen that restricts airflow. If a vent cover is broken or loose, arrange a suitable repair that keeps the vent functional.
Look closely at doors and vents
Inspect exterior doors at the bottom and along both sides. A worn door sweep, torn weatherstripping, or a door that does not sit squarely can leave an entry gap. Close each door and check for visible light around the edges. Include garage doors and basement bulkhead doors, and make sure they close fully rather than leaving a corner raised.
Seal small, suitable gaps with materials appropriate to their location, and replace damaged door sweeps or vent covers. Keep in mind that foam or caulk alone may not stand up to gnawing in areas rodents can reach. Avoid sealing openings until you know they are not needed for ventilation or drainage and have considered whether rodents may already be inside. If you find repeated signs or inaccessible damage, Harbor Shield Exclusion can help assess next steps.
A careful exterior check can reveal gaps before they become an indoor problem. Inspect the foundation, roofline, utility penetrations, doors, and vents regularly, and record any damage you find. Seal openings with suitable materials, while keeping vents and drainage paths clear. If you spot signs of activity or cannot reach an opening safely, consider arranging a professional inspection.