We have a standard flap in the door to the utility room. I don’t notice any draft from the flap, even though the window in that room is open because of the stink toilet, hardly any cold air comes through. So they seal well. Our girls are let out by us. After I found a dried-up mouse in my wardrobe, I am a bit sensitive about that. They used to come in via the doorbell mat. You can teach them that very quickly. Meanwhile, they have a scratching barrel outside where they can cuddle up if we don’t respond. When we are on vacation, the two stay outside. For that, they have fur and their shelter.