# Location of Smoke Detectors From Wall



## Mule (Jun 22, 2010)

I was thinking that SD's are required to be at least 12" from a wall but I cannot find the regulation in the 2006 IRC.

Am I having flashbacks of the 70's?


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## mtlogcabin (Jun 22, 2010)

The manufactures installation instruction would provide the specific locations and distances. Here is a link to a good article

http://ezinearticles.com/?Smoke-Detector-Installation-Locations-and-Positioning-Requirements&id=3949593


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## raider1 (Jun 22, 2010)

There is no specified distance in the IRC for the placement of smoke detectors from a wall.

As mtlogcabin pointed out this requirement will be located in the installation instructions of the smoke alarm.

Chris


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## rogerpa (Jun 22, 2010)

See NFPA 72-07 11.8.3.1-.5

http://www.nfpa.org/onlinepreview/online_preview_document.asp?id=7207#


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## Mule (Jun 22, 2010)

Thanks for the information. Based on what I could find the minimum distance to a wall is 4 inches. The 12 inches stuck in my brain was maximum distance from ceiling.


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## Yankee (Jun 22, 2010)

right, 12" max distance vertically from the ceiling if placed on a wall, 4" min away from the wall if placed on the ceiling. And, watch out for fans.


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## TimNY (Jun 24, 2010)

What Yankee said.  If asked where they go I simply say 'follow the instructions that came with the alarm'.  During inspection if they don't follow the 12"/4"/3' rule I ask to see the instructions.  I try not to tell people how to install them.  Who knows, maybe some new detector will have a different location.


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## FM William Burns (Jun 24, 2010)

Additional spacing information

Also make sure they keep them a minimum of 3’ from air handling diffusers/registers, bathrooms and (bedroom interior doorway dead zone) since smoke entering a room will bypass this zone and cause delays in notification while filling up the upper layer before filling this space. Also keep them off exterior walls. (source NFPA 72 Household.......)

ooooops...see that TNY covered the 3' issue...sorry!


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## Mule (Jun 24, 2010)

The return air is why there is a problem. This house was a bad design when it comes to SD's. See photo below.

View attachment 144


View attachment 144


/monthly_2010_06/572953b72eb35_SDClosetowallamp.jpg.f589f026ad69d82e00be573231e02863.jpg


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## FM William Burns (Jun 24, 2010)

Yep, that's the definition of of a void zone application.  See contractors try to do it all the time on residential plans and rough in's.


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## TimNY (Jun 24, 2010)

FMWB would that be true even if the smoke alarm was 3' from the return air grill and 12" from the wall?  Never heard the term void zone, but seems to me that a dead-end like that would not be appropriate no matter what the distance, as smoke would be sucked into the return before it reached the smoke alarm.


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## FM William Burns (Jun 24, 2010)

Void Space & Dead Zones

Tim,



Yes that is correct; the void or dead zone are areas are where smoke and heat can bypass the detector similar to beam and pocket ceiling areas.  Corners are similar areas as the illustration in the annex of 72 for proper location for detectors shows.  The interior of doorways are similar spaces where smoke can bypass a detector placed just inside the doorway.  I have an engineering diagram and some manufacturers have diagrams addressing this in their installation instructions.  I’ll dig it up and post a picture when I get back to work next week.


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## Pcinspector1 (Jun 25, 2010)

It would be in the builders best interest to pull the SD out from the wall in case the buyer wants crown moulding!

Also a SD in a hallway near a kitchen with a dropped header can trap steam making the SD go off if too close to the header. Happens when we boil things like pasta or hot dogs!


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## peach (Jun 25, 2010)

don't forget ceiling fans... the air flow from the fan is going to affect the SD performance.. just like supply and return air will.. most SD manufacturers limit the distance to the fan blade tip.. just as if it's an air grille (supply or return)


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## FyrBldgGuy (Jun 28, 2010)

Check the latest on NFPA 72 the 4 inch rule goes away.


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