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I installed hard-wired and interconnected smoke alarms through the house. I wondered, though, if a fire spread through my attic I might not know about it until the ceiling or roof collapsed.

Should I install an interconnected alarm in the attic?

Is there some reason this isn't required/recommended?

11 Answers 11

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FEMA writes:

Few, if any, smoke alarms are Underwriters Laboratories (UL)-listed for use in the temperature extremes an attic can experience. Few, if any, codes require alarms in one- and two- family residential attics where nearly all (90 percent) of attic fires occur.

“Attic Fires in Residential Buildings”, Topical Fire Report Series 11(6), January 2011

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    only 90% of attic fires occur in the attic?
    – Steven
    Dec 10, 2012 at 20:24
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    @Steven, 90% of attic fires occur in one- and two-family residential attic. The remaining 10% occur in the attics of other kinds of buildings. Dec 10, 2012 at 20:27
  • Given this data, it surprises me that attic alarms are not required.
    – Matthew
    Dec 10, 2012 at 21:33
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    @MatthewPK, “Residential building attic fires […] comprise [only] approximately 2 percent of all residential building fires.” (same source) Dec 11, 2012 at 10:31
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    @VebjornLjosa: "2 percent" means a 1 in 50 chance of a fire that most likely will not be detected when you most need detection (while you're asleep (or even awake - like my friend's neighbors who weren't aware of lightning strike - caused attic fire while they were awake)) until much later than ideal to avoid injury or even death. Imho, those are plenty significant odds to warrant a detector requirement esp. considering the relatively minor cost vs. benefit. And that's assuming "2 percent". Per article at "www.standardrestoration.net/what-causes-an-attic-fire", it's closer to 10%.
    – Tom
    Nov 16, 2021 at 3:16
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As a firefighter that recently battled a large and rapidly moving fire that appears to have started in the attic, I found myself searching the topic of smoke alarms in attics. Though it is a low percentage of structure fires that begin in the attic, they are not isolated incidents.

Chimney fires can easily extend into attics as well as HVAC units can ignite unknown attic fires. Our recent fire seems to have occurred from a malfunction in exposed flue pipe (non-bricked/rocked) extending through the attic before exiting the roof. Attic spaces are generally open and vented allowing for rapid spread of the fire where as living space fires can be more compartmentalized slowing the spread of flames.

It is estimated that our recent fire burned for ten to fifteen minutes before the 911 call was made. At this point the fire had self vented through the exterior of the home and the 911 call was made by passing neighbors. Though we were on scene in 7 minutes from the time our alarm tones sounded, it was far too late to save this home. Fortunately, the two residents home at the time of the fire were able to escape with pets and records stored on their laptop computer. The house was a total loss; but I have to believe if a little investment had been made for a smoke detector that endures the attic temperatures, this home could have been saved with far less damage.

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    Wish someone had a recommendation for a quality extreme temperature smoke detector for attic spaces. I was in mine working on a separate issue and realized I was crawling around 20 cy of highly combustible loose fill cellulose insulation.
    – a coder
    Dec 28, 2017 at 20:57
  • Most loose fill cellulose has been treated using ammonium sulfate and borate as a fire retardant
    – DaveM
    Jan 10, 2021 at 18:06
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We specify a "heat detector" in the attic and crawl spaces of all our homes. A "smoke detector" will pick up a neighbor's burn barrel smoke (products of combustion) but a heat detector operates on the "rate-of-rise" principle. That is to say, when the attic gets hot quickly (not just from a hot summer day) then it will go into "alarm".

This is the same unit we use in commercial kitchens too.

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If you sleep better at night with an attic smoke detector, they do make detectors for extreme temperatures. They go from -15 to + 200 degrees Fahrenheit.

The only problem with these is the dust in most unfinished attics. If you have a workman in they will stir up the insulation and create dust. Smokes are very sensitive to dust. But if there is some bad wiring smoldering in the insulation it can save your life. You will just need to vacuum it out say twice a year, and keep it close to the opening.

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I service thousands of smoke detectors every year and they should NEVER be installed in an attic. There are reasons code does not require them in attics but code is a MINIMUM requirement. If you want to provide additional protection for attic exposure the proper device is a heat detector. Smoke detectors are not designed to function in the high temperatures found in attics. Smoke detectors are not designed to function in the low temperatures found in attics. Smoke detectors are not designed to function in the humidity found in attics. All of these environmental issues will lead to erratic operation and cause false alarms or non-alarms. False alarms will provoke the disconnection of the detector, then it is useless. A properly rated heat detector is the correct fire detector to use in attics. Yes, there are special smoke detectors that will survive and function in the attic environment but you better open up your wallet very wide, not just for the detector but for the related hardware required that goes with it.

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I'm an electrician so I wanted to chime in and maybe clear up some of the confusion.

The reason we don't install smoke alarms in attics is because attics are rarely insulated the way the rest of a house is. There is a constant rising and lowering of the temperature (very hot in summer, very cold in winter) which messes with the circuitry inside leading to false alarms and no alarms. Attics also tend to be very dusty and smoke alarms often mistake excessive dust particles for smoke particles which, once again, leads to a false alarm.

Maybe down the line, someone will invent one that is impervious to these conditions but for now, we install HEAT DETECTORS in attics instead. They are programmed to go off should the temperature reach a certain degree (usually around 135 F). Someone pointed out that heat and fire rises so by placing these heat detectors ABOVE the rest of the house, they work very efficiently as the attic is one of the first places to heat up before a fire spreads.

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Why smoke alarms are not mandatory in attics is beyond me. Ask any firefighter if they have one in their attic and the answer is yes We found out the necessity for attic smoke alarms the hard way, when our brand new, completely built to code, fully inspected home had an electrical fire in the attic, RIGHT ABOVE AN INTERIOR SMOKE ALARM.

I awoke to use the bathroom, upon returning to the bedroom I heard a strange noise, sounded like rain on the bathroom vent, or on a tin roof, but far, far away. Hmm, odd, I thought, didn't hear that in the bathroom, must have just started raining, and went back to the bathroom to check.

That moment of "hmmmm, this is strange" saved our lives...when I returned to the bathroom there was no noise. In my half awake state my brain decided there must have been a storm the night before...branch must have put a hole in the roof... the noise must be rain on the ceiling...noise is right where the fuse panel is... This odd, disjointed ramble of thoughts had me immediately pull the kill switch on the entire fuse panel. I was still NOT thinking fire, never occurred to me the sounds I was hearing were fire.

Knowing water and electricity do not mix I mentally debated whether I should call the fire department - I didn't want to be one of "those" people who waste emergency services due to panic. I wasted critical, valuable minutes before calling the fire department, ...I almost opened the attic hatch to look (this could have literally been fatal), all because I could not grasp WHY the smoke alarms had not gone off, IF there was, actually, a fire. Finally, thankfully, I called the fire department, evacuated all humans, 11 dogs and sundry other pets, and only once I exited the house did I become aware of the massive amounts of smoke coming out the eaves and roof vents.

We had smoke alarms directly below the fire, in our master bedroom; in the hallway outside of our master bedroom; and across the hall in the spare bedroom. These were all useless in our case, as smoke RISES and the fire was in the attic. Had I not woken, had I not heard the odd noise, had I not investigated the odd noise...well, to be frank, we would have slept until the burning roof collapsed on top of us.

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    So, what brand(s) and model(s) did you and/or the firefighters you've asked get for the attic? Did you / they have any problems with false alarms (e.g., due to temperature extremes / dust) with that or other models you may've tried, as other posters have claimed is the reason why it's not recommended for the attic? My friend's neighbor just had a fire due to a lightning strike to the roof while they were awake and didn't realize it until neighbors told them. What was the range of outside and/or attic temps since you've installed it?
    – Tom
    Nov 15, 2021 at 21:10
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Now Smoke & Heat Detector is used for fire alarm.

NFPA 72, 2010 Edition, Chapter 29, Section 29.5.1 Required Detection, states the following:

29.5.1.1 Where required by other governing laws, codes, or standards for a specific type of occupancy, approved single and multiple-station smoke alarms shall be installed as follows:
(1) In all sleeping rooms and guest rooms
(2) Outside of each separate dwelling unit sleeping area, within 6.4 m (21 ft) of any door to a sleeping room, the distance measured along a path of travel
(3) On every level of a dwelling unit, including basements
(4) On every level of a residential board and care occupancy (small facility), including basements and excluding crawl spaces and unfinished attics
(5) In the living area(s) of a guest suite
(6) In the living area(s) of a residential board and care occupancy (small facility)

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    I'm guessing this was downvoted because, while pertaining to smoke detectors in general, it doesn't answer the question explictly. I think if you did a prologue highlighting that section 4 Excludes unfinished attics, it would improve your answer. Also, a citation of WHERE in CODE this is found (a brand reference does not give a universal requirement)
    – HerrBag
    Feb 28, 2013 at 14:14
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Tonight lightning struck a home about a dozen houses away from mine. The fire department was called, and checked things out and then left, they did not see any fire. About 1.5 hours later they were back, cutting 2ft x 2ft holes in the roof between the rafters with chain saws and flooding the attic with water. The house is a wreck now. I know that they have heat cameras and use them a lot and still they failed to detect the fire in the early stages.

Code may not require a smoke detector in attics, but I can't see how it's a code violation to put smoke detectors in attics. If you put an ordinary detector in the attic and they go off and give false positives then you try others until you find some that will work in that environment. Based on what I saw today, putting a detector that works in your attic has a HUGE cost/benefit payback.

Not so sure that a heat detector would give the same advanced warning as a smoke detector. If you're not in the attic moving around, doing stuff, the air can be very clean because the dust has long settled.

Add the tricky nature of detecting combustion/fire caused by lightning strikes to the reason why putting smoke detector in the attic is a good idea.

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I had a house fire in 2000. The whole top floor was gutted and all rooms downstairs were water damaged (except one toilet). It started in the gutter (by a chimney sweep) where waterproof paper caught fire and they carried on working. About 10 minutes later, when their feet became hot (they were wearing work boots), they came and alerted me. I rang the fire department, they took 12mins to arrive. By that time the whole house was ablaze. Another 10 minutes later, the regulation, wired smoke alarms on the ceiling went off (that's half an hour after the fire took hold).

So, I would always have them in the attic space. It is true the heat may be too much for them, that just means that you buy good quality German ones and replace them if they fail.

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I am baffled that smoke detectors in attics aren't more common. We suffered a catastrophic fire in our 3-week old home when the house next door, under construction, went up in flames and our roof caught. We were outside the home at the time but were shocked to discover that it took 20 minutes after the roof first caught fire for our smoke detector to go off. Because of the location of the fire the top of our staircase did burn, so I shudder to think what would have occured if this had happened in the middle of the night. When we rebuilt we added detectors in the attic, as well as ladders built below window frames in our kids' rooms... just wouldn't be able to sleep otherwise. I can't understand why smoke detectors are not standard.... the only other person I know who had a house fire had it start becuase of lightning, also on the roof.

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  • So, what brand(s) and model(s) did you get for your attic? Did you have any problems with false alarms (e.g., due to temperature extremes / dust) with those and/or other models you may've tried, as other posters have claimed is the reason why it's not recommended for the attic? My friend's neighbor just had a fire due to a lightning strike to the roof while they were awake and didn't realize it until neighbors told them. What was the range of outside and/or attic temps since you've installed it?
    – Tom
    Nov 15, 2021 at 21:11

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