I am installing smoke alarms in my 1930s house. I'd rather not drill into the plaster at this time, but I want to get them mounted. I have drywall beads along the top of all my walls, so I was thinking that I could mount the smoke detectors using some rare-earth magnets. They can hold the weight, but I don't know if the magnets will interfere with the smoke detectors. I've searched around, and it sounds like some smoke detectors can be tested with magnets, but that is it.

Is mounting smoke alarms with magnets going to render the smoke detectors ineffective?

Edit: Thanks for the answers. I'm going to go with a more solid approach, and either find the studs or use an full anchor. Given the importance of fire detection, it's not worth the risk.

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    Does the installation instructions show a minimum distance on wall to ceiling? (Or minimum distance on ceiling to nearest wall?). It's been awhile since I've done it, but I seem to remember the documentation showing minimum distances to the nearest 90degree angle. – Tyson Jan 2 '18 at 0:21
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    Good decision. Don't sacrifice your safety for aesthetics. – ArchonOSX Jan 2 '18 at 8:38
  • Side note - a 1930's plaster job could easily have asbestos in it. DO take all precautions for your health, and capture and dispose of dust safely. I had confirmed asbestos in 1980s stippling on a lathe and plaster ceiling. – Criggie Jan 2 '20 at 22:51
  • Thanks for the heads up. I wish asbestos was as easy to test for as lead. – Erick T Jan 3 '20 at 21:01

Smoke detectors should not be mounted within 12" of the corner of the wall.

The air movement in the corner is practically nil thus rendering the detector useless. It needs air movement through the unit to work.

  • Thank you for pointing out the requirement of proper placement, but using a command strip or its like terrifies me. Fires can get quite hot well before the smoke alarm alerts and personally I wouldn't trust that. – Matthew Wetmore Jan 2 '18 at 3:24
  • @MatthewWetmore Good point I wouldn't use adhesive or magnets myself and the OP apparently came to the same decision. – ArchonOSX Jan 2 '18 at 8:39
  • your accepted answer does suggest the alternative of using a command strip - which the manufacturer indicates weakens around 125F (51C) - I'd suggest removing that so others coming to your answer don't take that as a recommended approach. Thanks! – Matthew Wetmore Jan 2 '18 at 17:03

For a life safety device, I'd strongly caution against improvising an attachment. You need to respect positioning the smoke alarm for effectiveness, and a secure attachment that will not be compromised before and during its alerting. Depending on the type of the alarm, fires can progress significantly before they alert (see NIST link for smoke alarm tests.) It would be a major problem to have the alarm fall to the floor and not alert at all or stop alerting as the fire grew.

Expect both magnets and adhesives to be affected by heat.

Magnets, for instance, lose strength as they approach the Curie point. That temperature varies by material, but is well within the range for a room fire..

Command strips, from their FAQ, hold up to around 125F (51C.)

Good resources include:


I wouldn't use a powerful magnet to mount it. It could easily interfere with the circuitry. It's not something I would take a chance on.

Maybe mounting to the top of a wall with something temporary, like maybe a Command strip (they probably wouldn't work well on a ceiling)

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