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Preventing pests from entering is more effective than controlling them after they establish. Sealing gaps where utilities enter, caulking cracks in foundations, installing door sweeps, and screening vents keeps common pests out of the home.
From your pest prevention and control planning work, you understand that successful pest management prioritizes denying pests the three things they need: food, water, and shelter. Exclusion — the physical act of sealing every path into the building — addresses shelter so completely that food and water management become almost irrelevant. A mouse needs a gap the size of a dime to enter; a cockroach needs a 1/16-inch crack; ants exploit gaps invisible to the naked eye around utility penetrations. The premise of exclusion is that your home's exterior is a boundary you can actually defend, and that doing so once correctly is more durable and less toxic than ongoing chemical control.
Your caulking and weatherstripping background gives you the core skill set. The difference here is the inspection methodology: you are not caulking cosmetically but systematically hunting every penetration in the building envelope. Start from the foundation and work up. Foundation-to-sill connections are prime entry zones — gaps between the concrete and the framing above it admit insects and, in older homes, mice. Utility penetrations — where pipes, conduit, cables, and HVAC lines enter the building — are almost always undersized and surrounded by gaps; these get foam-backer rod plus caulk or, for larger gaps, steel wool packed tight (rodents cannot chew through it) followed by foam. Door sweeps close the gap between the door bottom and the threshold, which is the first thing to check if you see evidence of crawling insects along baseboards. Attic and foundation vents require hardware cloth — 1/4-inch galvanized mesh — which allows airflow while blocking rodents and large insects.
Material selection matters. Standard paintable caulk seals gaps aesthetically but is not a pest barrier — it can be chewed through. Polyurethane foam (like Great Stuff) expands to fill irregular gaps and cures to a rigid material that resists compression; use the "minimal expanding" variety near window frames and door jambs to avoid warping. For exterior penetrations exposed to weather, use silicone caulk, which outlasts latex in UV and temperature cycling. Copper mesh or steel wool packs into gaps before foam, creating a rodent-proof core that foam alone cannot provide. Hardware cloth (galvanized 1/4-inch mesh) is the standard for vents, weep holes, and any opening that must stay open for airflow.
The inspection itself should be done from outside on a bright day (interior darkness makes gaps visible as light) and repeated from inside at night with a flashlight. Common overlooked entry points include: where the chimney meets the roofline, garage door weatherstripping (often degraded and rarely replaced), the intersection of exterior stairs or decks with the house framing, gaps behind exterior light fixtures and outlet covers, and the gap between window frames and rough openings visible only from inside. Once sealed, maintain a "clean zone" — a foot of bare ground or gravel along the foundation — so you can detect fresh pest activity at the perimeter before it migrates inside.