So my house with 5200 sq ft living space, with high end finishes, plus a 3200 sq ft framed out basement with a finished wine cellar and 3 car garage is worth only $40,000 more than a 3200 sq ft house with no basement and a 2 car garage. Both sitting right next to each other on 20 acre parcels with killer views. Zillow is useless in my book. Perhaps it has some value in a densely housed area with cookie cutter tract homes, but for anything else it isn't worth the powder to blow it away.