1- In/near the kitchen or in air streams passing by it.
2- In/near the garage.
1 In the hallway outside all bedroom areas (or where people sleep).
2- Where a portable heater, humidifier, or other appliance is operated.
3- Inside every bedroom where someone sleeps with the door closed.
4- At both ends of a hallway with bedrooms when the hallway is more than 40 feet long.
5- At the bottom of a basement stairwell.