A gap no wider than a pencil can be enough for a house mouse to enter a crawl space. The goal isn’t simply to close obvious openings, but to find and reinforce smaller entry routes around foundations, vents, pipes, and access doors.
We have provided rodent control in Olympia and Longview since 1975, drawing on more than 100 years of combined pest control experience. For homeowners preparing to keep rodents out this fall, a durable plan combines a careful exterior inspection, chew-resistant repairs, and safe handling of any evidence already under the home.
Seal the Gaps Rodents Actually Use
Mice can fit through an opening about 1/4 inch wide, and rats can squeeze through a gap about 1/2 inch wide. A foundation crack, loose utility penetration, or bent crawl space vent screen may look minor from the yard, yet provide a dependable route under the house.
Sealing cracks and openings at foundations, pipes, wires, and vents is one of the longest-lasting ways to control rodent access. Inspect joints where different building materials meet, including siding-to-foundation transitions and areas around plumbing or electrical lines.
Choose Chew-Resistant Materials
Foam, caulk, plastic, and wood alone aren’t reliable barriers against gnawing. For vents beneath the home, use 18-gauge, 1/2-inch mesh galvanized expanded metal or 16-gauge, 1/2-inch mesh galvanized wire cloth. Secure the mesh without leaving gaps around the edges, and make sure the access cover fits tightly and resists chewing.
Caulk can finish a properly fitted metal repair, but it shouldn’t be the only barrier. Before sealing an opening, record its location and inspect nearby areas so another route a few feet away doesn’t remain exposed.
Inspect Entry Points & Exterior Routes Together
A complete inspection follows the paths rodents use to reach the space beneath the home. Walk the foundation slowly in daylight, then use a flashlight to check the access area and visible interior conditions.
Focus on these common trouble spots:
- Foundation gaps, cracks, and older ground-level openings.
- Utility penetrations for pipes, wiring, cable, and heating equipment.
- Crawl space vents, vent screens, and the access door or hatch.
- Wall and roofline openings that provide another route into the structure.
- Low branches and utility lines leading toward roofline entry points.
We treat house mice, Norway rats, and roof rats. Norway rats often use ground-level gaps in older foundations and utility corridors, while roof rats use overhanging branches and utility lines to reach roofline openings. Trim limbs at least 6 feet back from the roof to limit access to rooftops, attics, and soffit vents.
Beneath the home, look for fresh droppings, nesting material, gnaw marks, tracks in dusty areas, and torn or displaced insulation. These signs indicate an active problem. Sealing every opening immediately risks trapping rodents inside.
Remove Food, Water & Shelter Near the House
Exclusion works best when the property offers fewer reasons for rodents to stay nearby. Ready access to food, water, and sheltered travel paths encourages them to keep testing repaired areas for another way in.
Address the conditions that draw activity toward the foundation:
- Store household food and pet food in airtight containers.
- Keep trash cans covered, secure compost and bird feeders, and remove fallen nuts or fruit.
- Trim shrubs and vegetation back from the structure.
- Maintain plumbing and drainage so leaks or standing water don’t persist near the house.
Repeat the exterior check after yard work or a storm. A shifted trash lid, new branch growth, or damaged vent cover can undermine otherwise sound exclusion work.
Clean Rodent Waste Without Spreading Contaminants
Don’t sweep or vacuum dry rodent droppings, urine, or nest debris. Dry cleanup can send contaminated particles into the air, so disinfect the material first.
Wear rubber, latex, vinyl, or nitrile gloves. Spray contaminated material until it’s very wet with a labeled household disinfectant or fresh bleach solution, then let it sit for 5 minutes. To make a fresh bleach solution, use 1.5 cups of bleach per gallon of water, or 1 part bleach to 9 parts water.
Wipe up the material with paper towels, then place the towels and debris in a sealed plastic bag for disposal. Bag contaminated exposed insulation for removal rather than attempting to clean it in place.
A confined under-home area, widespread contamination, or damaged insulation requires more care than a small surface cleanup. Complete control and exclusion before the final cleanup so new activity doesn’t contaminate the area again.
Know When Exclusion Requires Professional Control
Homeowners can handle basic maintenance such as trimming vegetation or replacing a clearly damaged vent screen. Active signs after repairs, multiple possible entry routes, inaccessible areas beneath the home, or substantial droppings and insulation damage call for a full assessment.
Our process begins with an inspection to identify the rodent species and entry routes. We then place traps or bait stations strategically along travel routes, seal access points, remove nests and droppings, and schedule follow-up visits to verify that activity has stopped. Outdoor rodenticide use requires a Washington State Department of Agriculture pesticide applicator license; licensed pest control professionals carry the appropriate license.
The priorities are straightforward: inspect every likely opening, reinforce it with materials rodents can’t readily chew, and avoid disturbing droppings while they’re dry. If you need assistance with exclusion or cleanup, Pest Stop offers free estimates and same-day weekday service in Olympia at (360) 506-6033.