How to find where mice are getting in
Check the usual gaps first. When several openings remain possible, use repeated overnight detections to decide which area to inspect next.
Check the usual gaps first
Most searches for an entry point start with the building, not a device. Look for gaps, chewed edges, droppings, and rub marks at the places mice commonly use. CDC’s sealing guidance lists these locations inside and outside a home.
- Inside: under and behind kitchen cabinets, behind appliances, around pipes under sinks and washing machines, around water heater and furnace lines, floor vents, closet corners, and where floors meet walls.
- Outside: where the foundation meets the ground, around attic and crawl space vents, around windows and doors without weather stripping, and around holes for electrical, plumbing, cable, and gas lines.
- Up high: rafters, gables, eaves, and soffits.
When several openings remain, narrow the search
If the walk-through leaves several possible openings, do not read one night of playback as a finished route map. Use it to make the next physical inspection smaller and more deliberate.
A total tells you how much motion the sensors recorded. Playback adds order: which positioned sensor triggered first, which followed, and where the last detection occurred before the record went quiet. The first and last detections can help you decide where to inspect, beyond checking only the busiest sensor.
Anchor every label to the floorplan
Sensor A only becomes useful evidence when everyone knows where Sensor A was placed. Record height, orientation, and the nearby building feature when those details affect what the sensor can detect.
- Confirm each sensor label before the monitoring night.
- Mark moved or obstructed sensors before comparing results.
- Read timestamps alongside position, not as an isolated event log.
Place sensors beyond the first and last detections
If the earliest repeated detections cluster near one side of the monitored area, reposition a small number of sensors beyond that edge. If the latest detections repeatedly occur near another boundary, test that edge separately rather than assuming the two points establish direction.
The purpose is to ask a narrower question on the next night. Do not fill in an unrecorded path or identify an opening without physical evidence.
Inspect for the opening
Inspect the narrowed area for an actual opening or route. The floorplan playback directs attention; the physical condition establishes what should be repaired, sealed, or tested next.
Sources and scope
What a sensor record can’t establish: The first or last triggered sensor narrows the inspection. It does not verify an entry point, nest, or direction of travel.
The method reads detections in time order against a placement log, identifies a repeated edge that deserves attention, then asks a person to inspect and verify. It does not infer a route from one first or last event. That sequence is consistent with CDC survey recordkeeping and EPA inspection-and-monitoring practice. For food establishments, the FDA Food Code is a model that calls for routine inspection for pest evidence and protection of outer openings; local adoption and site requirements vary.
CDC: How to Seal Up to Prevent Rodents
Examples of interior and exterior locations to inspect for gaps and openings.
CDC: Integrated Pest Management: Conducting Urban Rodent Surveys
Mapped inspection records and active-sign observations that keep a sequence grounded in place.
EPA: Pest Control in the School Environment: Implementing IPM
Inspection, monitoring, recording, and evaluation as a decision cycle.
FDA: Food Code 2022
Model provisions on routine premises inspection for pest evidence and protected outer openings.
This is product-method guidance written by RodentRadar, not a site inspection report or a government compliance opinion. No review or endorsement by CDC, EPA, FDA, or another government agency is claimed here; the responsible field professional must verify the cause on site.