How many Smoke Detectors / CO is necessary?

Surely a common question, but:
How many smoke/co detector you need to have? Is it one per room, one per floor? What’s your recommendation?

For CO, install it close to the floor or up in the ceiling? How many is too much?


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Also you should check your local building codes. These can vary based on where you live.

They may have other rules beyond # and placement.

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thanks! @tgauchat and @E_Sch, will look into it.

Per the code where I’m at, we have to have one in every bedroom and major living areas. My 2,500 SqFT house has a total of 7 detectors, and I’m in the process of rolling out the Halo detectors.



What made you choose the Halo over other ones such as the nest or birdi???

I ask because I am looking something I don’t want to regret getting and prices are no cheap either. Thanks

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The two biggest factors for me choosing Halo were that they’re hard wired and they integrate directly with SmartThings. The Nest requires you to use Nest Manager and doesn’t allow you to directly connect via Zigbee or Z-Wave. The First Alert unit directly integrates with SmartThings, but only has a battery version. I researched for a couple of months before purchasing the Halo units. It also helps that Lowe’s has them on sale for $89. :slight_smile:


That’s a good price! Do they have a battery option? I noticed in my house (moved in recently) the previous owner installed 2 wired ones in the basement (Family) and battery operated in the main floor. Would it be recommended to wired all of them or just keep them the same way? Where I live (NY) either is fine.

Is there an advantage between wired vs battery besides that the battery last a few years?

The Halos are hard wired with a “backup” battery that is good for 10 years. For me down in Texas, current code requires hard wired detectors with a battery backup. The other advantage to wired detectors is the interconnect. This means that if one detector goes off, it sends a signal over the wire and sets off all of the other detectors. This is great for me because I have a two story house with a two story guest house out back. Those are the two reasons I went with hard wired. With all of that said, I don’t think the Halo is designed to run on battery alone. If you want to run wiring to your main floor then a Halo would be great. If you don’t want to run wiring, something like the First Alert would work fine.

Just a reminder that the First Alert Z-Wave versions are:

  1. Not interconnected (unlike their other wireless model).

  2. One-way only (ie, they send alerts and battery status to SmartThings, but you cannot trigger them to alert from SmartThings.

They are still reliable and useful and affordable.

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I placed one smart smoke/co detector per floor and covered the rest of the house with regular smoke detectors.