Remodel Answers · Safety & Prevention · Smoke & CO Detectors
Where exactly should I put carbon monoxide detectors?
Short answer
One on every level of the house, one within 15 feet of every bedroom door, and one near (but not directly next to) any combustion appliance — furnace, gas water heater, gas range, attached garage. Mount at outlet height or higher; CO mixes with air, unlike smoke, so ceiling mounting isn't required.
Where NOT to put them
Directly above a gas stove (false alarms from cooking), in a bathroom (humidity), within 5 feet of the furnace itself (normal transient CO during startup), or in an unheated garage (won't operate reliably below 40°F).
Why WA cares specifically
Washington State law (RCW 19.27.530) requires CO alarms in every new and existing residence. Older homes may be missing them; adding is inexpensive and non-negotiable if you have any combustion source in the home.
Signs of a real CO problem
Multiple people in the household with unexplained headaches, dizziness, or flu-like symptoms that go away when you leave the house. If the alarm ever sounds, leave immediately, call 911, and do not re-enter until the fire department clears the air.
What we see on Free Onsite Consultations
Based on real experience across the greater PNW, safety & prevention issues like this are among the ones homeowners most often miss until they become expensive. Our Free Onsite Consultation catches them early — while they're still a maintenance item, not a repair.
How the Free Onsite Consultation works