Q. In the last two weeks, we have seen two rats in the legal offices where I work! The rumor is that they’ve been seen elsewhere in the building, too. This is a ten-story office building that is not in the best part of town, but I can’t believe we have rats inside. How do we even begin to get rid of them?

A. It is pretty unusual to have rat problems inside an office building, while mice are fairly common. As you can imagine, when rats do occur in offices, they cause a great deal of excitement. Rats in office buildings cause significant damage by chewing on wires, shredding stored materials, and damaging equipment such as computers and telecommunications systems.

Rats can easily move from area to area, and floor to floor, in an office building. They can run horizontally through suspended ceilings and sometimes inside raised floors or utility conduits. Rats can also move up and down from floor to floor inside hollow columns and boxed-in utility runs.

The first thing is to hire a professional pest control company to do a complete rodent inspection of the entire building. Either your property manager, maintenance staff, pest control company, or ideally all three working together will need to get answers to some basic questions in order to successfully control the rats. The following questions should be answered for each floor of the building.

1. Where are rats most active? Make note of where there have been rat sightings by office workers, where rat droppings or other rat evidence (gnaw marks, nest material) have been seen, and where workers have heard rats scrambling in the walls and ceilings. Since rats regularly travel hundreds of feet, you will need a systematic inspection of the building to plot out on a floor plan all activity areas (rat runs, nest sites, feeding sites).
2. Where are the rats feeding? Identify all food sites in the building. Restaurants and cafeterias are most likely to be the primary feeding sites, but many office buildings have stores on the ground floor (drug stores, one-stop shops, etc.) that may be providing food. Other likely sites include food trash storage areas, food storage areas, office lunchrooms, vending rooms, trash compactor rooms, and loading docks.
3. How are the rats getting inside? In many ways, this can be the hardest question to answer. Rats may be getting into office buildings through underground conduits, sewers, and other invisible routes. It’s more likely however, that they are entering through typical entry sites such as the loading dock, open doors, holes and cracks in the foundation and walls, roof access, and the like.

Once the extent of the rat problem has been established, the pest control company will set up a control program that may involve trapping and/or baiting, plus rodent-proofing or eliminating rat entry points. The work should be scheduled to cause minimal disturbance to office activities.