Rodents: Small Creatures/Big Problem
While it's impossible to determine exactly how many rodents live in the U.S., some experts suggest that there could be one rat for every single person. By current numbers, that's more than 325 million. And they multiply a lot faster than people do. In just one year, given ideal circumstances, a single pair of rats could multiply into 1,200, and a single pair of mice into as many as 5,000. The numbers quickly become overwhelming. It's perhaps not surprising, then, that rodents eat or contaminate at least 20 percent of the world's food supply each year. They also transport fleas, lice, and ticks, have been linked to asthma, and carry diseases including rat bite fever, hantavirus, leptospirosis, murine typhus, and even the bubonic plague. Rodents present a problem that is exponential to their size.
Why It Matters To You
Rodents are as relentless as they are prolific. Rats have the ability to gnaw through a disturbing number of materials, including plastic, wood, aluminum, brick, cement, and even lead. They can climb with ease, swim considerable distances and tread water for several days. When looking for food or shelter, they can be relentless in their efforts to make their way inside your building. And once inside, the damage escalates quickly. In addition to contaminating basically everything with their nibbling and excrement, they are also capable of significant structural damage. Gas lines, electrical wires, water pipes, support beams, walls, floors and windowsills are all at risk. Rodents are also capable of burrowing beneath the ground, which can lead to foundation collapse.
For these and many other reasons, experts across the globe agree that exclusion – creating physical barriers against rodents to prevent them from entering a building in the first place — is the most effective pest management strategy available. Exclusion involves using rodent proof materials to seal up all cracks, crevices and weaknesses that rodents might exploit to gain entry. This is not an easy task — a mouse only needs a hole the size of a dime to squeeze its way inside, and a rat only needs a hole the size of a quarter. But finding and protecting these weak spots is fundamental to safeguarding a building.
Take it from the CDC, which lists “sealing up holes inside and outside the home to prevent entry by rodents” as its number one suggestion in preventing rodent infestations. Or the New York City Department of Health and Mental Hygiene, who recommends “sealing all cracks, crevices, and holes in walls, cabinets and doors” as its top guideline for controlling conditions that promote pests. The importance of exclusion is well-documented and widely publicized.
What Can Stop a Creature That Can Be Tenacious Enough to Chew Through Lead?
While the need for exclusion is uncontested in the industry, there are still some discrepancies as to which tools are suitable for the job. Occasionally, some experts will offer caulk, mortar or spray foam as inexpensive, easy-to-use exclusion tools. Unfortunately, these products often provide little to no protection against creatures whose teeth can gnaw through concrete. Steel wool is also popular in the exclusion discussion and while usually a better option than caulk and foam, steel wool requires regular replacement because it can rust and decompose over time. Copper mesh is another exclusion material sometimes recommended. This material is likely to deter a rodent, but the sheer amount of it required to fill a small hole can make it a very expensive solution, plus it’s a softer metal without sharp edges so it can be difficult to create a tight seal which means the mesh can easily become loose over time, rendering it ineffective.
The most effective exclusion materials on the market today include stainless steel or other permanent elements that will not degrade over time. There are online retailers dedicated to exclusion who offer a wide range of specialty products to protect cracks and crevices, and other problem areas.
Where Do I begin?
Exterior doors, garage doors, loading dock doors, vents, and at points where electrical, water, gas, sewer and HVAC lines enter a building are all common entry points that should be protected. Rodents can also gain access through weep holes, small cracks in the foundation, and beneath roofing tiles.
For all of their scurrying in the shadows, it is also very common for rodents to brazenly walk right through – or perhaps under – the door. Personnel doors, garage doors and loading dock doors are all at risk. Exterior doors should remain closed whenever possible, and sheet iron flashing should be installed at the base of wooden doors, which are vulnerable to rodent gnawing. One common misconception is that standard, rubber door sweeps used for weather sealing are sufficient to keep out rodents. Not true! A standard rubber door sweep won't last the night against a determined mouse or rat. Instead, install door sweeps that are built especially for deterring rodents and have been proven effective.
Another critical yet often-overlooked area in exclusion is loading dock doors. The small gaps beneath and around loading dock doors are susceptible entry points, as is the gap around dock levelers. Rodent-proof seals should be installed on all dock levelers and overhead doors. Vertical side seals are also important because rodents will not stop at ground level attacks.
A Comprehensive Approach
The Mallis Handbook of Pest Control is the leading industry guide and offers additional exclusion and sanitation guidelines:
- 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.
- Trash must be disposed in clean, tightly-sealed containers and stored as far from the building as possible. Trash removal should be frequent enough to ensure the containers are not a reliable rodent food source – ideally two or more times per week.
- Standing water attracts rodents, especially rats. Gutters should be free of debris and channel water away from the building. Leaky faucets, pipes and air-conditioning units should be repaired or replaced.
- Avoid clutter as much as possible – boxes left on the ground are popular nesting grounds for rodents. Cabinet bases, storage shelving voids and the tiny space behind appliances are also prime targets.
- Employees should be trained to notice and report evidence of pests (e.g. rodent droppings in undisturbed areas), which indicate a pest problem that should be addressed immediately.
A comprehensive exclusion plan combined with good sanitation is the safest, most effective pest management strategy available. Pest management professionals can and should be engaged to implement and monitor an effective plan. They should include exclusion as part of their services, and many even offer employee training assistance. With careful exclusion, monitoring and diligence, it is entirely possible to protect your building against even the most invasive of pests.
Drew McFadden is the Director of Research and Marketing for Xcluder Pest Control Products, an exclusion brand used by pest management professionals around the world. McFadden has been serving the commercial and residential pest exclusion industry for many years, touching all levels of the food supply chain from production to retail.