Gap under door.

During a commercial inspection, I'm always focused on identifying potential insect and rodent entry points. Exclusion of pests from your building should be the first line of defense. Preventative exclusion of pests is far better than after-the-fact treatments and applications to remove an existing infestation. Common entry points are broken screens, eroded weatherstripping, exterior doors that don't fully form a seal when closed, and gaps around pipes and wires entering the building.