When nights cool, roof rats and house mice move toward warmth. Trapping the ones already inside is only half the job — if the entry points stay open, the next one is a week behind.

Mice fit through a gap the width of a pencil; young rats need about a half-inch. The common openings: where utility lines and pipes pass through an exterior wall, the corners of a garage door where the seal has worn, gaps under soffits and at the roofline, weep holes without covers, and the space where a deck or porch meets the house.

How to find every gap

A flashlight test works from the inside: turn off the lights in the attic or garage at dusk and look for pinpricks of daylight around vents, pipes, and the roofline. Anywhere light gets through, so can a mouse.

Seal it properly

Steel wool packed into a gap is a stopgap; rodents pull it out. Copper mesh or hardware cloth backed with sealant, or sheet metal for larger openings, is the durable fix.

Why timing matters

Do the trapping and the sealing in the same window — trap the interior population, close the building, then confirm the traps go quiet. Seal first and you risk locking an animal inside; trap without sealing and youre re-running the same job every few weeks.