Exclusion: Most Powerful Weapon in Fight Against Rodents

The gap beneath exterior doors is a very common access point. Any clearance below the door must be smaller than 1/4 inch. It is a common misperception that standard rubber or bristle door sweeps are sufficient to protect this area. While rubber sweeps may help keep out the elements, they provide little to no protection against rodents. Even the smallest of rodents can gnaw through a bristle or rubber door sweep in the course of a single night. Metal brush seals pose a larger obstacle for rodents, but overtime they dent and deform leaving gaps that rodents can exploit to gain entry.

Specialized, rodent-proof door sweeps are perhaps the single most important exclusion tool available. Xcluder Rodent-Proof Door Sweeps, for example, feature reinforced rubber gaskets lined with Xcluder fill fabric—a blend of stainless steel and poly-fiber that has been tested and proven effective against rodents by USDA/APHIS. The reinforced edge prevents rodents from gnawing on the sides of door sweeps, and the fill fabric’s sharp, coarse fibers cannot be gnawed through by rodents. This type of specialized, rodent-proof product is fundamental to proper exclusion. Rodent-proof seals should be installed on all dock levelers, garage doors, and overhead doors. Vertical side seals are also important for dock doors because rodents will not stop at ground level attacks.

A simple method for testing door frame vulnerability is at night. Turn on the brightest light in the room or warehouse and step outside to see if any light is escaping around the door frame. If light can get out, pests can get in.

Additional rodent entry points that need protection include places where electrical, water, gas, sewer, and HVAC lines enter the building, beneath roofing tiles, and through small cracks in the foundation. The Mallis Handbook of Pest Control offers a practical set of exclusion guidelines for those tasked with protecting a building against rodents. Here are a few examples.

• Ventilator grills and windows should be protected with proper exclusion materials, ensuring any voids or cracks are filled.
• Defective drain pipes provide a transportation pipeline for rodents. A perforated metal cover should be cemented over the drain pipe, and any small openings surrounding the drain where it enters the building should be patched or filled with proven exclusion materials.
• Large sidewalk cracks should be sealed, as these crevices allow rodents to access a restaurant’s foundation and search for entry points. Foundation walls can be protected with barriers of metal, concrete, or brick around and below the foundation.
• Circular rat guards should be placed around all vertical wires and pipes.
• Ensure that cracked or broken roofing tiles are replaced as needed and utilize exclusion material to fill any voids.

The Right Tools for the Job

A comprehensive exclusion plan—one that identifies potential access points with a fine-tooth comb and constantly monitors for changes and weaknesses—is the most effective approach to protecting a building from invading rodents. A diligent plan, however, is only as effective as the barrier products installed. Caulk, mortar, and spray foam are occasionally recommended as exclusion tools. While appealing, given they are inexpensive and easy to install, these products offer little to no protection against rodents. A creature that can gnaw through lead pipes will certainly not be deterred by spray foam. Steel wool is another popular exclusion material. Though stronger than caulk and foam, steel wool faces rusting and decomposition over time and therefore requires regular replacement. Copper mesh, a more expensive solution, is effective against rodents when properly installed. However, this is not an easy task as a tight seal is difficult to secure, and the mesh often becomes loose over time. It is also a softer metal, lacking the sharp texture that discourages rodent gnawing.