Ask the Expert (Pest Control)

Rodents: How Are They Getting In, How Do We Stop Them?

• By Drew McFadden
• 10/01/17

It’s critical that pest problems be identified and addressed as quickly as possible because rodents breed quickly — a single pair of rats can multiply into 640 within a year, and mice can multiply to over 1,000. Stopping them for good means finding the points of entry and sealing them up to prevent future invasion. Below are some of the most common entry points and exclusion solutions. Remember, when conducting your inspection, mice can fit through a gap of about 1/4 inch and rats through a gap of 3/8 inch.

Common Entry Points and Solutions:

• Exterior doors — Damaged or worn out sweeps are one of the most common entry points. Most standard brush or vinyl sweeps keep out the weather but not mice and rats. All doors should be fitted with specialized rodent-proof door sweeps.
• Vents and grilles — Protect them with screen or mesh and ensuring any voids or gaps around them are filled with a pest exclusion material.
• Drain pipes — Rats are excellent swimmers. Make sure exterior drain and sewer access points are covered with an appropriate metal cover. Openings surrounding the drain should be patched or filled.
• Vertical wires and pipes — Mice and rats are excellent climbers. Circular rat guards should be placed around all vertical wires and pipes.
• Utility and other building penetrations — Check places where pipes, wires or HVAC enter the building and fill any gaps with pest exclusion material.

Ensure the exterior of the building, especially around the foundation, is free from harborage areas such as shrubs and ground cover, and eliminate any “bridges” to the roof, like overhanging trees.