Board Thread:Help Desk/@comment-24895598-20140503061419/@comment-24821572-20140524101827

A picture of the house itself would be better than a map version of it. If those lines in the middle  are platforms, they won't be valid as a ceiling. Also, even if you make a too huge of a box with doors and everything, it won't be considered a housing even if it would normally fit the criteria.

A simple solution is to make a small room in that house, and make the NPC stay there.