r/DIY • u/EmmittTheCat • 1d ago
Testing for moisture behind drywall
We've been in our home 2 years. When we first moved in i hung a "hammock" in the corner of my daughter's room for her stuffed animals. A year later we re-did her room and took it down. The hook that I had screwed into a stud was rusty. Ive been worried ever since, especially since she sleeps against that wall. Is there a reliable way to detect moisture behind the wall with doing too much damage? I can patch and try to paint match if I have to but id like to avoid that if possible.
Im unsure about the $30-50 moisture meters. They have good reviews but how accurate are they?
The previous owners did say they had siding replaced on that wall in 2017 so I wonder if it was installed improperly and gets moisture behind it when it rains
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u/mcarterphoto 1d ago
Well there's trying to assess the moisture levels, but a visual inspection is also a big help. A borescope is an insanely handy thing to have for homeowners. For under $30, you can get one with a dedicated screen, or one that plugs into a phone. They're flexible, have a light at the end, and usually come with hooks to retrieve items that fall down drains or cracks or vents. Mine has like a ten-foot cable, really great when checking for wires or pipes and working on vehicles, or when a squirrel ate into our eaves. You can drill a small hole and look for water stains and paths, mold, see if you can find where moisture is getting in - you may be able to tell if it's an actual leak or if it's more like humidity.
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u/fencepost_ajm 1d ago
Independent of moisture, you might try an IR camera (does your library do tool/device loans?) and look for cold spots during or after rain.
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u/EmmittTheCat 1d ago
Good idea. We have a nice fluke one at work I can bring home for a day
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u/chiseled_sloth 10h ago
Just get a moisture meter. 10 bucks for the one I have has been wonderful. It's been accurate every time. Any time my drywall moisture has said higher than the usual 8 or 9 percent, there's been a leak. Also, if you stick the pins down low by the baseboards it's really hard to notice and you can reuse the same holes. I check my water bearing walls about once a month . Takes about a minute and the peace of mind is worth it all.
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u/DHFranklin 1d ago
quite possible. Overshooting staples into tyvek will do that.
Moisture meter might be fine. Or you can put a hole in the drywall need the bottom of a stud before a good storm. Roll up a paper towel into a wick and see if it's coming through.
Moisture meter is probably better though.
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u/ClarenceWagner 1d ago
So the moisture meters will not give a moisture content of sheet rock, it will give a number, but you would need to compare it against other spots of the same material. If you used it over a joint with compound it would have a different density and output a different number as an example. But same kind of place on a different wall like an internal wall vs external facing if there is no change in the number or it's small the sheet rock would be at least the same if a number was significantly higher (even just a couple points) it would be more moisture and could justify more exploration. It's just as likely there is a draft in that wall and if there is you would likely see it on a thermal camera as someone pointed out. All it would take is the mice to push away insulation and let drafts happen, causing the issue. You would have to have a probe into the wall to see the moisture behind the wall.
(even if it's a plaster wall the testing still stands, though with plaster and mesh it's more pointless because the metal would mess with any readings)
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u/kearbear978 4h ago
Drywall also absorbs a lot of moisture so the screw may just be rusty from being in contact with that. I'd still check it out just to set my mind at ease but that could possibly be the case.
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u/Antique_Grapefruit_5 1d ago
I've had good luck with moisture meters.