Pest Exclusion Tactics
The best way to prevent most structure pests is with some form of exclusion. If they can’t get in, the problem solved! As various pests enter different ways, there are a lot of places to inspect. Start with pest exclusion for pests you know have historically invaded the structure.
Pest Exclusion by Species
Rodents- Focus exclusionary efforts around the bottom 4 feet of the house. While you will want you to look at higher areas too. The most critical areas are closer to the ground. Best materials to seal with include quick-setting cement, copper mesh, concrete crack filler, roof pitch caulk, aluminum flashing, and treated lumber. Mice cannot easily chew through these materials. If you must use any urethane spray foam, make sure it is only the “pest-proof” brand. Carefully inspect and replaced damaged rubber door seals. If pests typically chew them, replace them with “excluder” wire reinforced seals.
Squirrels- Focus exclusionary efforts around the rooflines and upper eves of the structure. Flash all possible openings with aluminum flashing. Install “Nixalite” type porcupine wire in areas they persistently frequent to gain entry.
Bats- Focus exclusion efforts around roof eves, offsets, attic vents, ridge caps, and upper structural features. Bats will occasionally enter around foundation level areas, but that’s not the norm. Best materials to seal with include hardware cloth, foam exclusion strips, caulking (silicone or roof pitch). Spray foam is effective for bat exclusion but may leave a slight appearance if you’re not extremely careful. I usually reserve that idea for any sealing I would rather do from inside the attic. While gable attic vents come screened from the factory, these screens are often so cheap or poorly fastened, bats and birds push them loose or even make holes in them. I’ve even seen these screens move loosely enough that critters use them like doggy doors to go in and out.
Insects- Of course, insects are the most difficult pest to keep out and cracks must be caulking tight. Start with the bigger openings and do as much sealing as seems practical. Evaluate your progress from one year to the next and keep sealing tighter until problems stop. Overwintering insects like paper wasps, ladybugs, cluster flies & stink bugs detect heat loss and come in high around roof eves and soffit. Most ground spiders will squeeze in around loose door seals, basement windows, and foundation gaps. These need to be as tight as possible. Concrete crack filler is often helpful with masonry gaps.
While exclusion efforts take time, they don’t typically require much material, and any effort you make always benefits you two ways. First by excluding pests and second in insulation value. Keeping out the cold outside air could even be the greater benefit!