📋 Steps
1
Walk the full perimeter with a flashlight at ground level
Get low — crouch or use a mirror. Gaps visible from standing height represent only a fraction of actual entry points. A flashlight at ground level reveals gaps in the foundation, at the sill plate, and in the stucco-to-concrete junction that are invisible from above.
2
Probe gaps with a pencil — anything a pencil fits through is a mouse entry
A mouse can compress its body through any gap a pencil (6mm) passes through. Any gap meeting this criterion needs sealing. Mark found gaps with chalk before sealing — easy to track progress.
3
Inspect all pipe and utility penetrations
Every point where a pipe, wire, cable, or conduit enters the foundation or sill plate is a potential entry. Check: gas line, water lines, cable TV, electric conduit, HVAC refrigerant lines, dryer vent. Fill with copper mesh and seal with silicone caulk or expanding foam.
4
Check garage door seal and service door threshold
The garage is often the largest unprotected entry zone. The rubber gasket at the bottom of the garage door compresses and gaps over time. Service doors between garage and interior should have tight-fitting door sweeps. Check both.
5
Inspect the roofline from the ground with binoculars
Roof rats and squirrels access attics through gaps at the fascia-soffit junction, damaged vents, and roof-wall junctions. Check these from ground level with binoculars — damage is often visible. Repair any gaps larger than 1/4 inch at the roofline.
💡 Tips
- The two highest-ROI pest exclusion investments: door sweeps on all exterior doors and caulking all utility penetrations — combined cost under $200, prevents 80% of mouse entry
- October is the optimal inspection timing — mice begin seeking winter harborage in October-November in most of the US. Completing inspection before peak pressure is far more effective than reactive exclusion after mice are already inside
- Take photos during the inspection — before and after sealing — to document work done and create a record for future reference
- Expanding foam is excellent for large gaps but mice will chew through it. Copper mesh stuffed into the gap before foam provides a chew-resistant core
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