Leak sensor in wall cavity - bad idea?

Leak from an ice storm is wreaking havoc. Water crept in through a wall cavity. Think we fixed the issue, but not 100%. While the wall is open and drying out, the thought occurred to me to throw a leak sensor inside the wall cavity, to give me an early alert if the leak recurs. Does that raise a red flag to anyone as a bad idea safety-wise? Battery powered device inside of an exterior wall with insulation...my hesitancy is regarding a fire risk. I shouldn't do this, right?....But, I mean comon', no way that would actually cause a fire...

Not sure about regulations (or good/bad ideas regardless) for batteries in a wall cavity, but a similar idea that avoids the issue: can you use one of the sensors with an external probe? Then you can put the battery portion of the unit in a more convenient spot.


I suppose, but then I'd have to put a plant or something there to hide it. I wouldn't be able to stand the look of it! Maybe a good idea as a temporary thing until I can be confident enough that the issue has been resolved.

How would you replace the battery?


I wouldn't. It'd just be left there once it died, at which point hopefully I'd be confident that the leak won't recur. I bet the battery would last a good while though.

The Sensative leak sensors have a 10 year battery - allegedly. Are you looking to detect actual water or dampness? The leak detector would detect water... not sure how it would react to a slow absorbtion leak... like where the material got damp and absorbed moisture but didnt really get "dripping wet." Though maybe that isn't really an issue here if there's enough water in there!


I would install a low voltage gangbox/blank wallplate then get a sensor with probe. Mount the sensor to the wallplate. This will monitor for future event with ease of access.

Gang box



Hmm. Interesting idea. I'll chew on that one for a bit. Thanks!

And then you can hang a picture over the wall plate!


Another thing to consider is your vapor barrier. In Manitoba, where I'm from, I would be really hesitant to have a hole in the poly layer that goes around the house. Just don't forget to seal it, if you do have a wire there.

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AFAIK there is no NEC rule for battery things in the walls. They barely deal with class 2 wiring.(12V LED power)

However I would not put anything in my wall with a Lithium battery. Lithium's have been know to explode when they get too hot. And come to think about it, Alkaline's leak when old. I don't know if a leaking alkaline battery could have some follow on consequences.

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So for clarification....

this is not plumbing related but rather water infiltration?

This was my question; in that long before you have water on a sill plate or somewhere puddled you usually have damp insulation/backing and sheet rock moisture build up. A humidity sensor would be more preemptive.

I think I'd be looking to leave that access hole open for some time to make sure you have appointed all the right layering and diversion to shed water ....then just button it up once you've had enough testing/weather to be sure.

If this was ice dam related it's one thing...if this was snow melt that's another; if the same thing happens from rain/driving rain that's another...exposure & solutions overlap. Either way there are ways to go about this that would have you 97% sure because you'd have like 3 levels of treatment and diversion backing each other up.

While you are at it, I'd be checking every point of the house where the same convergence of wall/ceiling/roofing/flashing/cladding might be posing the same problem that you just haven't caught yet.

Oh, and consider calling your insurance company. They get off far too often on stuff like this that we should be calling them to pitch in some $ for.

One other thing, consider getting a moisture sensor/probe that you can stick into wood & sheetrock to see if you have anomalous moisture levels anywhere you are concerned. The mold that results from this kinda problem is bad news, a hassle to remediate, and can linger on your disclosure upon sale. I'll see if I can dig up the name of the stuff frequently used to treat active mold and / or suspect wetted materials that you are leaving in that cavity.


I was gonna suggest that too. I have one of those and they work really well. You don't even need anything all that accurate as long as its consistent, because what you're really looking for is a change against the baseline. I used one when I was tracking down a leak and it was a godsend. And I used it to determine when. things were dry enough to repair.

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Yeah, water infiltration from an ice storm. Maybe ice dam. Not sure. I have a remediation company taking care of all of it, so no worries about lingering dampness. But at this point identifying the cause with certainty seems elusive, thus the desire for a sensor. I agree a sensor with moisture detection and maybe even humidity would be the way to go.

Leak on bottom floor? If yes do you have a crawl space below the leak? I ask because you could drill a hole in the bottom of the wall cavity into the crawl space and put the sensor down there as water would seep through the hole. Or you could push a probe up through the hole from crawl.

If second floor or on slab, never mind.

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Ah, now there’s an idea. I like it! Yes, it’s on the first floor with a crawl space.

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I did that in an apartment. I passed speaker cables from a linen closet into the living room. When I left I put on blank faceplates and nobody had any complaints.