Do you check your plant for pest proofing issues regularly?
External doors, windows, or other openings in your facility should have less than one-fourth inch or 6mm opening when closed to prevent rodent pests from entering. That includes openings created by accident (e.g., damaged wall structure) and those left by external contractors after construction work has been completed (e.g., installing a new roller door or building an expansion).
It is generally recommended that you should check your plant for pest proofing issues regularly to ensure no uninvited visitors come onsite.
The easiest way to check is to look for light leaks. On a bright sunny day, check a rather dark area in your plant for sunlight visible from the inside. At night, walk around the exterior of the building and look for light leaking out of the facility from holes or gaps in the outer structure.