what does a room need to be ready for an npc to move into it in terraria

Answer 1

needs to have a space of about 8 wide and 5 high, not  including walls and roof,

can have a door or wooden platforms for entry points,

back must be completely covered by a proper wall, suggesting wood, brick walls no longer allow npcs to spawn

must contain 1 table, 1 chair and a light source

 

try this

http://img810.imageshack.us/img810/3572/npchouse.png