Where are mice getting in?

Tap a numbered spot on the house to see what to look for and how to seal it, then mark what you find. The CDC says a mouse can fit through a hole the width of a pencil, so small gaps count.

The seven spots

The house drawing covers the eleven entry points on the CDC’s lists of places to check outside and inside: the roof line, eaves and vents; the attic; doors and windows; the dryer vent; holes where pipes, wires, cable, gas and A/C lines come in; the foundation, crawlspace vents and the floor-to-wall joint in the basement; and the garage door seal. University extension guidance adds that doors, windows and screens should fit tightly and that foundation cracks 1/4 inch and larger should be sealed.

How to seal

The fixes follow the CDC: pack small holes with steel wool and put caulk or spray foam around it to hold it in place, and use lath screen, metal sheeting, cement or hardware cloth for larger holes. Nebraska Extension notes that latex, plastic, rubber and thin wood aren’t suitable on their own. One exception is the dryer vent: building codes forbid putting a screen over it, so the fix is a hood whose flap closes.

Signs mice are already inside

The six signs come from Nebraska Extension (droppings 1/8 to 1/4 inch long with pointed ends, gnaw marks, scratching sounds, nests of shredded material near warm spots and a musky smell) and Arizona Extension (dark rub marks along baseboards). Ticking any of them changes the summary to say mice are probably already inside and points you to trapping and safe cleanup.

Your answers

Mark each entry point as found a gap, looks sealed, or can’t check. The progress bar counts any answer. Everything is saved only in your own browser and never sent anywhere. The full list view under the drawing has every item for keyboard and screen reader use, and the Print button prints it.