Might be that we have more precise door builders than other parts of the world but from a German perspective that gap is huge and I don’t think I have ever seen one that tall on regular internal doors (as opposed to e.g. outdoor shed doors or similar places where insulation is taken less seriously).
What kind of tolerances do your doors have that cats can crawl under them?
¼" to ½" is all most cats need. They are surprisingly flexible
Since cat skulls are 1.5-2" in the smallest dimension, big X to doubt on this one. Unless your cat can deform it’s skull like a squeaky toy
https://www.youtube.com/shorts/qFzdp4iaQhs
definitely more than 1/4"
Might be that we have more precise door builders than other parts of the world but from a German perspective that gap is huge and I don’t think I have ever seen one that tall on regular internal doors (as opposed to e.g. outdoor shed doors or similar places where insulation is taken less seriously).
I’m in california in a shitty apartment and the door gap is the tip of my index finger to the first knuckle. Maybe 3/4"
It’s called an undercut, most are 1" and are to allow for air movement.