My house has eight smoke detectors; one in the basement, one in an upstairs bonus room, and six on the main floor. The main floor is "T" shaped; the bedroom area forms the top of the "T", and the rest of the rooms are in the "stem" of the "T", connected by a hallway. All of the smoke detectors are in the bedroom area. Here's a rough layout (the dots are the smoke detectors):

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As shown in the diagram, the main floor has no smoke detectors except the ones in the bedroom area (which are audible on the rest of the floor). Each bedroom or potential bedroom has one just inside the doorway, and there is another in the hallway just outside each doorway. I'm thinking of making the following changes:

  • Master BR: There is no door between the MBR and the adjoining hallway. The MBR has an 11 ft ceiling, so I need to drag a huge ladder from the garage at the other end of the house, and navigate it through doorways and hallways past breakable stuff to access this unit. Since there is one right outside this room with no intervening barriers, which also serves the MBth, I would remove the one inside the MBR.

  • Bedroom: I would leave the one inside the bedroom and remove the one in the hallway immediately outside it, which doesn't seem to serve any purpose.

  • Office: With smoke detectors located in areas on either side of this room and in the hallway immediately outside, the one in the room seems redundant. Also, the one in the hallway is unobstructed to the rest of the main floor, so it serves that area. If I removed the hallway unit and left the office unit, all of the alarms could potentially be behind closed doors and less audible in the rest of the house (which is an open floor plan).

    So I would remove the one inside the office and cover the electrical box with a plate. If a future owner wants to turn it into a bedroom and a smoke alarm is required inside the room, it would be trivial to put one back.

Question: Do these changes sound reasonable, or are all of the existing smoke detectors required by code (in Virginia)?

Impetus for change: At 3AM this morning, we were awakened to all eight alarms going off (they are interconnected, so they all sound if any one is triggered). It turned out that they are all 12 years old and one had an age failure (smoke detectors are supposed to be replaced after 10 years but the manufacture dates were hidden on the backs of the units).

So there will be the expense of replacement and then an ongoing requirement to periodically drag in a ladder, test each one, and replace batteries. There are also three extra sources of potential false alarms, and it is a long, nerve-wracking task to identify the source when all are blaring -- every unit needs to be removed from its wiring harness. I don't have an issue if each one serves a purpose, but it seems like the builder went nuts with smoke detectors and installed three more than apparently are needed.

  • It may be worth noting that a smoke "alarm" is not the same thing as a smoke "detector". A detector is a sensor for a centralized system and might not have any "sounder" function of its own, relying upon separate sounders/flashers. A smoke alarm always has an alarm function of its own.
    – Upnorth
    Sep 6, 2017 at 4:30
  • In the UK we use alarms with rechargeable lithium batteries, so no battery replacement for the life of the detector. We also have remote test/locate/hush switches eg aico.co.uk/product/ei1529rc-hard-wired-alarm-control-switch These are available in hardwired and radio-interlink versions.
    – Owain
    Jun 18, 2019 at 7:54

3 Answers 3


I'm in Va as well. You need one in every bedroom, then one in every room leading from the bedroom to the room with egress. Each county official interprets that latter part a little different.

In my county, he'd want one in each bedroom, then one in or near the hall.

  • They are needed at the top and bottom of stairs and any room that can be considered a bedroom regardless of it's present use.
    – Jack
    Sep 3, 2017 at 20:41

@NPM's answer mentioning possible differences in official interpretations of code prompted me to contact my county building office. They were extremely helpful and provided an in-depth answer. I'll share it since at least the gist may be useful to others.

About the code

There is a national code covering smoke alarms and other fire safety issues. Each state has a code that starts with the national code. They can add additional requirements but can't reduce any of the federal requirements. Each county can have a code that starts with the state code. They can add additional requirements but can't reduce any of the state requirements. So all of the codes are pretty similar, but some counties can have more requirements or be more stringent than others.

The code wording is somewhat vague, describing the intent more than the implementation. For example, the location of a smoke detector may be described as "close to" or "in the immediate vicinity of". The county building offices interpret and operationally define the terms. So in one county, one smoke detector in a hallway outside several bedrooms may be deemed sufficient. In another, they may interpret "close to" to mean within 10 feet, so several smoke alarms might be required in the same hallway. This is why some questions can really be definitively answered only by your county office.

Codes are periodically updated. In general, the code that applies to your house is the one that was in effect at the time it was built. So researching current codes may not give you the right answer.

Vague code wording relevant in this case

  • Code descriptions I found online seemed to state that a smoke alarm is required outside each bedroom, while one inside each bedroom is recommended but not required. Nope. One inside each bedroom is required.

  • The code refers to "sleeping rooms" rather than bedrooms. That seemed to imply that any in-bedroom requirements or recommendations applied to rooms used for sleeping rather than rooms meeting the definition of a bedroom. Nope. It applies to any room that meets the definition of a bedroom, regardless of actual usage.

  • There is a requirement for at least one alarm on every habitable level. For split levels, an alarm on an upper level is deemed to include the lower level if the levels are less than a full story apart and there is no intervening door. Logically, if the split was zero stories apart (say a hallway opening into a room with no intervening door), that would be less than a full floor apart and would imply that an alarm in the hallway would satisfy a requirement for one in the adjoining room. Nope. This doesn't apply to a bedroom requirement if an alarm is in an adjoining hallway next to the room.

  • The code requires an alarm outside each bedroom in the immediate vicinity of each bedroom. This seemed to imply that one alarm in the adjacent room or hallway might be sufficient for all connected bedrooms. Nope. "Immediate vicinity" was interpreted as within 10' of the bedroom door. The builder might have gotten away putting one halfway between two bedrooms, but then it would have been in the wrong direction relative to the egress from one of the bedrooms.

Bottom Line

All of the existing smoke alarms are required.

Really Bottom Line

I found another code provision that looked like the other issues might be moot even if my interpretation had been correct. It is a code violation for a tenant to remove or disable any existing smoke alarm. I suspected that the provision might also apply to the owner. It turns out that if the code is revised and an existing smoke alarm is no longer required, the homeowner can petition the county for approval to remove it. I wouldn't hold my breath for a code revision that reduces requirements, and if one happened, it likely wouldn't be worth the time and effort to pursue approval.

Bottom line clue

I probably should have realized that the builder didn't just go nuts with smoke detectors. That really isn't a selling point. Builders are very cost conscious and generally don't exceed code requirements without a compelling reason.

  • 1
    Sometimes, it is cheaper to install extra and guarantee a pass on inspection rather than try to save on cost and possibly have to come back due to a unfavorable interpretation of the code. Or it is cheaper to install the spec'd units on the plans rather than roll through an RFI process. In our area, we could easily have eliminated 2 smokes; but in the end the official can say what they want as long as the code is vague enough.
    – Damon
    Sep 11, 2017 at 10:10

You can get 3 packs of 10 year battery operated smoke and carbon monoxide detectors for about $50. I'd put those in and ditch the ones in electrical series. With one going off you can know where the problem is and if you choose, not go there.

  • I can appreciate the sentiment when a false alarm happens, but that's an unusual situation. The primary purpose of interconnecting the units is to buy precious time to save your life when there is an actual fire. If I need to leave the MBR unit in place, though, my plan was to replace that one with a unit with a 10 yr battery. The others are easier to reach.
    – fixer1234
    Sep 4, 2017 at 17:32
  • Also, at least in Virginia, being interconnected is required by code for new construction (and any residence built when that requirement was in effect).
    – fixer1234
    Sep 4, 2017 at 19:34
  • Sorry. Now I wonder if Home Depot in VA sells the battery only ones. I'm a Fire Safety Director in NYC. I need to know where smoke is not just that smoke is. Of course I have a fire alarm panel that tells me.
    – Jerry P.
    Sep 4, 2017 at 19:52

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