I am wiring an addition on an existing house. Does the code require that I install hardwired smokes in the existing part of the house as well or just in the new addition? The existing part will not be remodeled. Also, what rooms require smokes? Bedrooms, kitchen, livingroom, office, laundry room, hallways.....anything else? What about a walk-in closet located within a master bath? Attached garage, or unfinished attic containing a furnace. Thanks for the information.