User blog comment:Alixgirl11/Getting NPCs to Stay in their Houses?/@comment-4674838-20111216205723

Tip: when building an NPC room within your large house, put the NPC's living quarters above or below your main floor(s). NPCs will not jump/fall when they encounter a vertical gap of 4 or more blocks, so your guide wouldn't have access to other parts of your house with this kind of set up.