For several years now in California, having a carbon monoxide detector has been required in virtually all homes in The Golden State. This is not a point of sale requirement. It is a requirement for all residential dwellings which burn gas in any capacity (stove, furnace, etc.), or have a fireplace, or an attached garage as a matter of public safety. They are exempt in all electric homes that do not have an attached garage or fireplace.
Where are the carbon monoxide detectors to be placed? The carbon monoxide detectors should be on every level of the home, including the basement. If you live in a multi story home with the garage at the bottom, you do need one at that level also (just inside the door, once you are in the habitable area) as well as on the main floor, bedroom floor, and any other level you may have. In a single story home, just one carbon monoxide detector is sufficient.
Additionally, carbon monoxide detectors need to be in the bedroom area of the home. If a bedroom has a gas fireplace or wood burning stove (or any other fossel fuel source of heat), there must be a CO detector in the room. Otherwise, in the hall is fine. If bedrooms are not all in one part of the home, there needs to be a detector near each bedroom.
The cost of the device ranges considerably – from less than $10 each to more than $200 each. Some are plug in, some battery only, some feature LCD displays. Some are combination smoke detector & carbon monoxide detectors. Nest makes a CO alert, too. We put a First Alert detector in our house, and the cost was around $20 – $30, but there are many brands from which to choose. (You can also buy portable CO detectors.)
Once installed, it should be checked periodically (along with your smoke detectors) to make sure that it is functioning properly.
Remodeling your home? When you apply for permits, be aware that the city or county inspector who visits your property will be looking for smoke and carbon monoxide detectors. If you don’t have them where needed, your remodel will not pass inspection. Your inspector will need to return, and normally that results in an extra cost to you.
Carbon monoxide poisoning can be very dangerous, to the point of death. If you don’t have a detector, go get one immediately.
From the CalFire site (pdf):
From the City of San Jose: http://www.sanjoseca.gov/index.aspx?NID=5344