Smoke Detectors – A primer on Placement & Location

In the prior articles, we covered the proper maintenance of smoke detectors and many of the options available. In this article we will be discussing where smoke detectors should be located, and even how to prevent false alarms.  

The Starting Point – Current Codes

In order to answer the question of how many are needed or where they should be located – let us take a look at the most current codes being enforced for new housing and major renovations. Please note – many states, townships, and other locations may have a more stringent code than what is listed below.  

2006 IRC – R313.2 Location: Smoke alarms shall be installed in the following locations:
1. In each sleeping room.
2. Outside each separate sleeping area in the immediate vicinity of the bedrooms.
3. On each additional story of the dwelling, including basements but not including crawl spaces and uninhabitable attics. In dwellings or dwelling units with split-levels and without an intervening door between the adjacent levels, a smoke alarm installed on the upper level shall suffice for the adjacent lower level provided that the lower level is less than one full story below the upper level.
When more than one smoke alarm is required to be installed within an individual dwelling unit, the alarm devices shall be interconnected in such a manner that the actuation of one alarm will activate all of the alarms in the individual unit.

That’s all? – Well no, not quite

Again, please note: your local jurisdiction may require measures that are more stringent. Why? You will find that most professionals do not say we built it to code, but that we only see the codes as the minimum requirements. One example noted was by Barry Elings who commented that Combination units not only “may” be the best option but in some States but are required by their state code.

Iowa code: The law requires all newly constructed residential properties in the State of Iowa to be equipped with smoke detectors that have both photoelectric and ionization sensors. Existing homes do not need to have the detectors changed out if they meet the manufacturer’s recommendations for use, installation and life expectancy. However when it is time to replace smoke detectors in existing homes, they must be replaced with the dual-sensor (photoelectric and ionization) detectors.

I must also point out that many jurisdictions have not adopted these codes and are still using an older version. I would have to ask though – do you really want to base your family’s safety on older outdated codes?

Starting next January many locations will start adopting the 2009 IRC codes. To my knowledge, the only major change to the code (related to smoke detectors) is mandating a CO detector be installed in all houses with an attached garage or combustion style appliances. Personally, we feel that they should be in all houses, especially the newer ones that utilize an ERV or HRV.

I have an older house & need to replace my existing smoke detectors – what do I need to do?

The first step is deciding what type of units you have; are they battery powered, hard wired, or inter-connected? The next step is figuring out if you need additional units. At a minimum, one smoke detector should be installed on every level of your house, which should include the basement and near every sleeping area. For individuals who are sound sleepers, make sure you install a smoke detector inside their bedroom. Once you have know how many units you need and what type they are, you can start looking at the available options listed in the prior article.

I have on older house, how can I get interconnected units?

Most older houses are going to be battery powered only, and unless you are planning a whole house remodel, changing from a battery or hard-wired units to inner-connected units would be cost prohibitive and in most cases require a licensed electrician.

You could hire a specialty alarm company to hook up a whole house burglar alarm & smoke detector system, but in some cases, they are not allowed by code to be the only system utilized. If they are allowed by code in your area, you would have to confirm that if you no longer paid for the central monitoring services that the system would still work.

The easiest solution in this case is to be the wireless units that will talk to each other. When you do your monthly test, you should hear all the other detectors go off confirming that the system is working properly.

Where should I place the new smoke detectors / is the current location a good spot?

When you have purchased your units, they will come with directions for proper placement.  We will always recommend that you follow the manufacturer’s directions. Some basic rules of thumb though are:

  • Smoke rises, so smoke alarms should be mounted high on walls or ceilings. Do not mount the units directly in the corner as that is considered a dead air space & the smoke may not reach it.
    • A wall-mounted detector should be positioned with the top of the detector 6 to 12 inches below the ceiling.
    • A ceiling mounted detector should be positioned at least four inches away from the nearest wall.
  • Detectors should also be installed in or near living areas, such as dens, living rooms or family rooms. 
  • A smoke detector should be located at the top of each stairwell and at the each end of a long hallway (30 plus feet long)
  • If you celebrate Christmas or Hanukkah, a smoke detector should be placed in the same room that you would have your Christmas tree or menorah located.
  • To avoid false alarms, install smoke detectors at least ten feet away from stoves, fireplaces, and steamy showers / saunas. In most cases, you should not install a smoke detector in a bathroom or kitchen.  
  • Do not install smoke alarms within 3 feet of nearby windows, doors, ceiling fans, or forced-air registers. The moving air can blow smoke away from the detector and/or result in false alarms.
  • Do not place a smoke detector on an un-insulated exterior wall (basement) or ceiling (attic).  The temperature extremes can affect the batteries and the units themselves.
  • If you have a deaf or hearing-impaired family member that lives with you, make sure you buy an appropriate unit for their room. While you may think that you will have plenty of time to warn them or wake them up, the odds are truthfully against you.

Prior Articles:
Smoke Detectors – A primer on the Options Available
Smoke Detectors – A primer on Maintenance
Everything we owned… Winter Specific Tips on preventing house fires


    In buildings that were built in the “70”, in each apartment there is only 1 detector but these apartments have 2 -3 bedrooms. My question is; do we need detectors in each room of the apartment even tho it was built in the “70s”?? If i’m bringing it up to code, do I need the detectors in each sleeping area??
    Thank You.

    • Sean

      That is a very good question & one you should ask your local building official or fire marshal.

      While I listed the current codes in the article, every state or local has a say in which portions to accept, ignore or improve on. In some cases the issue of fire safety (especially in commercial / multifamily units) falls under the local fire marshal or another agency. In some locals, they will grandfather in the existing structure as is and only require you to upgrade to the current codes when you remodel the unit. In other locals, where there has been a major fire causing death, you might find them requiring all commercial buildings, motels &/or apartments to be brought up to a certain level.