The Gaps Rodents Use, and Why Steel Wool Is Not a Repair

The measurements nobody believes

A house mouse passes through a gap around six millimetres across. A rat needs roughly the diameter of a quarter. Neither figure is intuitive, which is why so many people are confident their house is sealed while rodents come and go every night.

Where they actually get in

Utility penetrations first: the hole cut oversized for a gas line, an AC line set, a dryer vent or a cable, then never closed. After that, the bottom corners of garage doors where the seal has gone hard. Then unscreened weep holes in brickwork, gaps beneath siding at the foundation line, open crawlspace vents, and the void where a deck ledger board meets the wall.

Why steel wool fails

It slows a mouse down and does nothing else. Rodents pull it out, and it rusts and stains. Real exclusion means hardware cloth or metal flashing mechanically fastened over the opening, sealed at the edges, with chewed timber repaired. Expanding foam alone is worse than nothing, because rodents chew straight through it and it conceals the evidence that they have.

Order of operations matters

Trap out what is inside, seal every opening, then verify activity has stopped. Do it in the wrong order and you seal rodents into the wall cavity, which turns a rodent job into a dead animal job. Trapping without sealing is simply a standing order, because the population outside is effectively unlimited and an open entry point advertises itself.

Do the work before the cold

The first properly cold week of the year reliably produces a spike in rodent calls. Sealing in early autumn is far less work than removing an established indoor population in January. If you would rather not crawl your own foundation line, call (877) 875-5384.

Call (877) 875-5384