I’ve done hundreds of rodent exclusion jobs in Central Texas, and the honest truth is that most of them could have been prevented. Not because the homeowner was careless, but because the entry points mice and rats use aren’t the obvious ones. They’re not the gap under the front door or the broken window screen. They’re the spots you’d never think to look — and that’s exactly why the pests know to use them.
Here are the ten spots I find problems at most consistently. First: pipe penetrations under sinks. Every plumber who ever ran a supply line or drain through an exterior wall left a hole larger than the pipe itself, and that gap is often stuffed with a wad of fiberglass insulation or nothing at all. Second: dryer vent flaps. The flap that’s supposed to keep outside air out when the dryer isn’t running can warp, stick open, or simply have a gap around the duct that the flap doesn’t cover. Third: weep holes in brick veneer. These are intentional — they allow moisture to escape behind the brick — but they’re also perfectly sized for a house mouse. Proper weep hole covers exist; most homes don’t have them. Fourth: the gap where siding meets the foundation. Settlement and weathering create small gaps along this transition that are invisible from a standing distance but obvious at crawl height. Fifth: HVAC line sets. The refrigerant and condensate lines entering the home through the wall are surrounded by a foam sleeve that rots and compresses, leaving gaps around the lines themselves.
Continuing the list: sixth is the garage door threshold, specifically the corners where the rubber seal meets the door stop — these wear and separate, leaving a triangle gap at each end. Seventh is the space behind the kick plates under kitchen cabinets, where the cabinet base meets the wall and floor and is never perfectly sealed. Eighth is the roof-to-soffit transition, especially on older homes where the fascia has pulled slightly away from the soffit material over time. Ninth is the attic turbine vents, which often have loose or missing bird screens that allow squirrels and rats access to the attic space directly from the roof. And tenth — the one that surprises people most — is the gap where your gas meter or utility disconnect panel is anchored to the exterior wall. Utility companies attach these with a single penetration and rarely seal around it.
None of these require a contractor to fix. Copper mesh, steel wool, and paintable exterior caulk handle most of them in an afternoon. For the weep holes and attic vents, there are off-the-shelf products designed for exactly this purpose. If you’ve already had a rodent issue and had it treated, walking through this list and addressing what you find is the difference between a one-time problem and an annual event. My record is finding eleven distinct entry points on a single house — number eleven was a hollow door sweep on the door from the garage to the house interior that had been hollow for years. The mice had figured it out before the homeowner did.