I think it's the Dresden Files mythology? But I always liked the premise that it's not the house that prevents them. It's the magic of a home. They could walk into some house a squatter is living in for a few days with no issues, but a home where people truly live make it their own, have families, memories...that's what gives the threshold power.
IIRC, even in that universe, a vampire can force it's way in, but the threshold strips it of most of its power if not invited.
I think it's the Dresden Files mythology? But I always liked the premise that it's not the house that prevents them. It's the magic of a home. They could walk into some house a squatter is living in for a few days with no issues, but a home where people truly live make it their own, have families, memories...that's what gives the threshold power.
IIRC, even in that universe, a vampire can force it's way in, but the threshold strips it of most of its power if not invited.