Where do you install carbon monoxide detectors in your home?

Are you confused about where to install carbon monoxide detectors? I hope I can paint a helpful picture for you today so you have a better idea what to do.

When are CO detectors required? First off, as of July 1, 2011, it became state law in California for carbon monoxide detectors to be installed. CO detectors are only required for houses that have either an attached garage, fireplace or gas heater or appliance. Technically, if a house ran on electric only, had no fireplace and a detached garage, it does not need a carbon monoxide detector.

Where should carbon monoxide detectors be placed? They should be installed specifically outside of each sleeping area in a house (there could be multiple areas), on each level of the house and in the basement also. You may only need one carbon monoxide detector in your house, but you could need several detectors depending on the layout of your home. Make sure to follow the manufacturer’s guidelines on the package first and foremost to ensure you have properly installed your detector. Moreover, if you’re unsure whether you need an additional detector or it is somewhat questionable, keep in mind detectors are fairly inexpensive. It’s better to be safe than sorry, right?

Here are some examples for you of various scenarios for determining how many carbon monoxide detectors are needed.

Example 1: There is one small hallway connecting all bedrooms in this single story house, so there is only one carbon monoxide detector required as indicated by the blue dot.

Example for carbon monoxide detector installation - by Sacramento Appraisal BlogExample 2: There are two different sleeping areas in this single story house, so there is a need for two carbon monoxide detectors as indicated by the blue dots. See the video below (or here) of a walk-through of this house.

Example for carbon monoxide detector installation - by Sacramento Appraisal Blog

Example 3: This is a two-story home with a need for three carbon monoxide detectors since there are two floors as well as two separate sleeping areas upstairs.

Example for carbon monoxide detector installation - by Sacramento Appraisal Blog

Here is a video tour of Example 2 above to help you visualize installation:

By the way, Sacramento County Code Section B-8 R315.1 and R315.2 says the following regarding where carbon monoxide detectors should be installed (exactly what I said above):

  1. Outside of each separate dwelling unit sleeping area in the immediate vicinity of the bedroom(s).
  2. On every level of a dwelling unit including basements.

Lastly, in case you did not know, carbon monoxide detectors are required by FHA since it is California state law. Since missing CO detectors are one of the most common FHA repair issues, it’s a good idea to install them before the appraiser inspects your home if you are doing an FHA loan.

I hope this was helpful. Let me know if you have any questions.

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  1. John Carlson says

    I was told that even an all electric home with no garage or fireplace has a electric stove and W/H which can remit some CO gas. Is the CO detector required in this case?

    • says

      Thanks John. If the home is an electric home, it probably wouldn’t have a gas water heater. If the water heater is gas though, then it sounds like a CO detector would be needed. If not, then there shouldn’t be a need for one when the home is all electric, no garage (or detached garage), no gas appliances and no fireplace.

  2. Dave says

    I just bought 2 CO detectors (KIdde ). I live in Florida and my house is all electric with an attached garage. I placed the detector’s in the garage just to see if they would get a reading. To my surprise they have displayed in 30-40’s on several days. The tonight they both chirped because they were reading 145/146. The car had not been moved all day and was never started. The garage does have 2 gas cans that have gas in it but otherwise there is nothing that has combustible fuel in it.

    It’s kind of hard to believe that both units are bad or are Kidde units known for false positives?


  3. says

    Dave, I am not really qualified to say whether your CO detector is a good one or not. I do know there is a quality spectrum, and I’ve heard the cheap ones from chain stores are not as good as the very expensive ones (I know, that sounds obvious). From personal experience, my son had a remote controlled toy in his room that would make our CO detector in the hallway sound an alarm when the toy was turned on. I don’t understand how that was happening, but it seemed the toy’s frequency was somehow interfering with the detector. I just know we had to get rid of that detector because it was not working as it should because it was creating a false positive (and the alarm was very loud). I bring this up to say that some CO detectors do create false positives. I do not recall the brand we had. It might be worth poking around online to see if others have had a similar experience with the brand you mentioned. I hope you figure it out, and obviously I hope there is no legitimate issue at your home.

  4. Jeff says

    Ryan, a question regarding locations of CO detectors in relation to smoke detectors…..

    If only one CO detector is required outside of multiple BR’s that share a hallway, but you still need smoke detectors inside of each of the BR’s, I’m assuming you can put one combo smoke/CO detector in each BR and be ‘overly compliant’ for the CO detector requirements and not require the one in the hallway?

    Also, I saw nothing in documentation that requires either smoke or CO detectors in other areas of the dwelling such as Living or Kitchen rooms. Although ‘more is safer’, do either need to be in any part of the dwelling other than the BR areas?

    Thanks in advance,

    • says

      Hi Jeff. Thanks for checking in. First, I should say the definitive source for the answers to your questions needs to be your city/county. With that being said, I’ll say smoke detectors are required in bedrooms in my area, but they are also required in the hallway outside of bedrooms. Thus in my area the plan to put a combo detector inside a bedroom wouldn’t fly because a smoke (and CO detector) needs to be outside the bedroom also. A smoke detector is often found in the Living Room too.

      In case it’s useful for any onlookers, here is some background on smoke detectors and whether appraisers require them: http://sacramentoappraisalblog.com/2014/01/23/do-appraisers-require-smoke-detectors/

  5. Janice says

    I have propane operated fireplaces in my bedroom. I keep my bedroom door closed all the time. Should I put a CO alarm inside the bedroom or just outside in the hall by the room.
    Thank you.

    • says

      Hi Janice. That is a really good question. I think the most qualified person to answer is your local fire department or your local county. You might want to call up the fire department and simply ask them for their input. They should know the answer. I don’t want to step outside of the scope of my general knowledge as am appraiser and offer you specific advice that should really come from the fire department or county. Thanks for stopping by.

  6. LInda says

    My mother passed away and we are selling her home in CA. The home was built in 1989 and there are no electrical outlets in the upstairs hallway where three bedrooms are located. Are we required to pay an electrician to install an outlet there so we can plug in a carbon monoxide device?

    • says

      Hi Norval. Thank you for reaching out. An appraiser can insist on smoke detectors in any location. If an appraiser is doing so before the inspection, it is probably because the lender client is requesting the appraiser to ask about. In the end if you are doing a refinance, and the appraiser has to come back out to check to see if smoke detectors are there, you are probably going to pay about $150 more to see that happen. If this is for a purchase, it could save the Borrower money to avoid an additional trip fee too. None of my clients make this request of me, but I have heard of some lender clients that do want appraisers to ask. I will say two of my lender clients are very strict about smoke detectors, and they hands-down want them installed regardless of the age of the property. I find in many of these cases the loan officer has talked to the home owner already about the issue, or at the least there has been a mention about a carbon monoxide detector. If you have any other questions, let me know.

  7. henree says

    I read most of the comments, not all. Just want to say that CO2 is heavy and it sinks to the floor. Smoke rises up to the ceiling. So combo detectors may exist but will not provide protection. CO2 alarms are placed close to the floor and smoke alarms generally on the ceiling or near it.

    • says

      Hi Henree. Thank you for the comment. I think there is wisdom in your words. Often CO detectors are added simply as a technicality to get a loan, but one has to ask what type of detector might be more optimal for actual protection. Being that I’m an appraiser, I tend to not offer advice about location or type of detector, but I will say it is worth considering. Thank you again.

    • Petro says

      In fact, CO (carbon monoxide) is slightly lighter than air. Therefore, ceiling is preferable place for it. Note that CO2 (carbon dioxide) is a very different gas and should not be confused with CO.

  8. graymoment says

    I’m having a little difficulty understanding the requirement. Are CO detectors required on every level regardless of whether there is a bedroom on that leve? If all bedrooms are upstairs in 2-story townhouse, could there be just 1 CO detector outside of that sleeping area?

    Also, what constitutes a separate sleeping area? Is it a distance from the other bedrooms? I have a situation where all bedrooms are upstairs. The master is off to the right and 2 other bedrooms are off to the left. Conceivably, a single CO detector could be put right at the top of the stairs?

    • says

      Hi Graymoment. Thanks for checking in. Yes, CO detectors are required on every level regardless of whether there is a bedroom on that level. If all bedrooms upstairs are located off the same hallway, it’s likely there is only one CO detector required. However, the letter of the law may have a different rule if the hallway is too long, so I want to mention that just in case. I won’t step out to be the expert on hallway distances, so I’ll defer to local code and the fire marshal on that one. A separate sleeping area would be a separate hallway or area where there are additional bedrooms (or just one bedroom). I included an example of that in the images above so you can see how one side of a house has a wing of bedrooms and the other side is a different wing of bedrooms. In that case there would be multiple CO detectors required. Realistically from an appraisal standpoint, a lender client will likely want the appraiser to report there is a CO detector upstairs and downstairs (and nearing the sleeping area somewhere), but they are probably not going to split hairs over an exact location (so long as it is outside of the bedrooms somewhere). I find most lender clients simply want a photo and a general description. As an appraiser, I want to avoid liability too, so I don’t say whether the CO detector location is working or whether the location conforms exactly with code or not. My job is to give a value to the house rather than interpret or report code. From a safety standpoint though, just be sure to read the fine print from the manufacturer of the CO detector as well as the fine print of local code.

  9. Richard says

    Henree has CO2 and CO confused. Carbon monoxide (CO) is not heavier than air and so does not sink to the ground. It’s density is slightly less than air and so it tends to mix hence a CO detector is just as effective at any height.

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