Talk:Home/@comment-4718425-20111230050700/@comment-4674838-20111231092649

NPCs cannot jump more than 3 blocks high. Also, they will not jump unless they encounter a solid obstacle while moving forward--at which point they will try to jump over the obstacle if it's less than 4 blocks high. In the current set up of your house, they cannot go up a floor because 1) it's more than 3 blocks high and 2) there's no obstacle to prompt them to jump while walking.

Also, NPCs can teleport to their room at night as long as no players can see them. So if you go exploring for a few minutes and come back, you might find that the merchant simply teleported back to his room. Generally just waiting for NPCs to teleport back to their room is the best thing to do.