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#68070 - 07/28/06 10:53 AM Smoke Alarm Height?
SteveFehr Offline
Registered: 03/19/05
Posts: 1192
Loc: Chesapeake, VA
I'm putting a couple smoke alarms up in a house with 11' vaulted ceilings- for 8' ceilings, I'd place them either on the ceiling or very close to it on the wall, but I know the batteries would never get checked if I did that here. Placing them at a height where they can be checked with a chair or small stepstool places them about 9' off the ground, and 18-24" shy of the peak of the vaulted cieling. Is this acceptacle practice? It's 3/12 slope of the cieling, btw.

[This message has been edited by SteveFehr (edited 07-28-2006).]
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#68071 - 07/28/06 11:10 AM Re: Smoke Alarm Height?
gfretwell Offline

Registered: 07/20/04
Posts: 9066
Loc: Estero,Fl,usa
I agree with you but we are in the minority. For some reason NFPA and the manufacturers have decided a detector in an unservicable location is better than one you can get at because of a minor increase in performance.
BTW this is really dependant on the manufacturer's installation instructions. NFPA72 only gives guidelines and defers to the instructions for definitive guidance.
The first manufacturer who labels his detector for an accessible area will make a fortune.

You also have to note the location of paddle fans. My wife got away with not putting detectors in the coffered ceiling trays because there was a fan in there.
Personally I think it borders on criminal to put a detector with user replaceble batteries where the user can't get to them. You know the first time he pays $100 or more for the service call to get someone up there they will tell the service tech to pull it down and throw it away. (I have seen it happen)
My wife was carrying the "duty pager" for her company for 2 weeks. She got 2 calls. One to disconnect a pool door alarm and one to move/remove a beeping smoke detector 27 feet from the floor. She could only tell them she was not allowed to do it. Call someone else.
Greg Fretwell
#68072 - 07/28/06 12:07 PM Re: Smoke Alarm Height?
SteveFehr Offline
Registered: 03/19/05
Posts: 1192
Loc: Chesapeake, VA
The manual says to refer to NFPA 72 for placement on sloped and gables cielings. It also says not to place them within 3' of the peak, which is difficult on a hallway only 4' wide. I don't have NFPA 72- would someone be able to give me a synopsis of the requirements?

Maybe I'll just move them and hope subsequent homeowners have a 6' stepladder... They're going to need them to change the light bulbs too, I suppose. It just stinks to have to pull out a ladder in the middle of the night when the alarms start beeping "dead battery" because they haven't been checked in 4 years.

[This message has been edited by SteveFehr (edited 07-28-2006).]
#68073 - 07/29/06 07:42 AM Re: Smoke Alarm Height?
Roger Offline
Registered: 05/18/02
Posts: 1779
Loc: N.C.
Steven, go HERE , then proceed to chapter 11, 11.8 covers the installation rules.

#68074 - 07/29/06 08:52 AM Re: Smoke Alarm Height?
renosteinke Offline
Cat Servant
Registered: 01/22/05
Posts: 5305
Loc: Blue Collar Country
Oddly enough, back in my mis-spent youth, I actually did some work for a major testing center, where it was my job to perform fire tests, and alarm systems. Tests were both limited 'bench' tests, as well as full-scale fires.

The real 'fly in the ointment' for smoke alarms is that pesky detail that most fires smoulder forever, before bursting into flames. The riddle is made more complex by the fact that the most common detectors are not particularily sensitive to "cold" smoke.

Anyway, in the full-scale tests, it was quite easy to see the smoke form a cloud near the top of the room. Any indentations, or projections, would have a visibly 'clear' area near them... imagine the cloud of smoke as a giant cotton ball! Even after the cloud was quite thick, there remained clear areas in peaks and corners.

The instructions are based upon these tests, and are intended to make the detector as effective as possible. That these are often places that are nearly impossible for the occupant to access is not one of the things the code considered.

The issue is right up there with lights placed were you'll never be able to change a bulb.

There are other solutions out there... light beams being but one... but these solutions will cost far more than the common $4 detector!
#68075 - 07/29/06 12:39 PM Re: Smoke Alarm Height?
SteveFehr Offline
Registered: 03/19/05
Posts: 1192
Loc: Chesapeake, VA
Roger: thanks for the link! I had no idea that was online

Looks pretty clear- the detectors need to be placed on the high side of the room, between 4-36" of the peak. Thanks all!


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