Builders are required by code/law to put them in the highest spot in a room. Also, codes now here in my country in VA require they be in every bedroom. I have one in my tray ceiling, which isn't very attractive, but it's the highest point in the room. I also have one over my bridge area between bedrooms since I have 20 ft ceilings in my family room and foyer. Our house is new and the builder explained the codes since people complain about where thedetectors are.