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I am not a stranger to minor home work, but this wall has me stumped. I am trying to hang an EV charger and cable hook, which while not huge, are enough I'd prefer them to be in studs. Simple enough, right? Queue this wall.

The wall separates the garage from the home, built 2015. As best I can tell, the wall is either a) a shear wall, b) something additionally insulated for fire code, or c) both. Stud finder, magnet, and tapping (best) are absolutely failing to find studs in most of this thing. The leftmost seam (in red) is definitely a stud. The other painted seams (in blue) have screws but are definitely NOT studs. The wall seems to be double-layered (or bizarrely thick) sheet rock with plywood or OSB backing. Those other visible seams are where the drywall is anchored to plywood, but not an underlying stud. Presumably this has to still be anchored to studs, but not in an arrangement I've seen. From the one I've verified, I've drilled 16" and 24" out and hit nothing, even redrilling +/- 1". Which leaves me with two overall questions:

  1. Where the hell are the studs in this thing? Regardless of the backing screwing up the detection methods, there has to be some kind of vertical framing in there, right? I'm at a loss for how else to find them short of a sawzall.

  2. If I'm mounting something <50 lbs, does it matter? I have to assume the plywood backing is anchored to studs, so using that should be more than adequate. I'm still not sure how best to do that. A lag bolt would grip the plywood, but most of the length would still be in drywall, which seems less than ideal. I'm leaning towards long toggle bolts that I would drill and expand past the plywood.

Any thoughts or suggestions would be helpful.

Wall

Wall - Marked

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  • See if you can measure the drywall thickness in one of those holes. It should be 5/8 if it's fire rated. If it's less, than there is likely some sort of plywood behind it as a fire barrier Sep 18, 2023 at 16:54
  • Are able to obtain the plans or are you able to talk to the builder? Sep 18, 2023 at 19:55
  • What's on the back of the wall? Did you try locating studs from the inside? If that bumpout is for a bathroom the studs may have been shifted for plumbing. @RohitGupta, plans won't show stud locations.
    – isherwood
    Sep 18, 2023 at 20:00
  • Thanks all. Will open up a bit more tonight so I can measure the drywall / OSB thickness. The other side is a kitchen, so there are cabinets and tiling there. There ARE two outlet boxes on the reverse side spaced 48" apart, though.
    – rndmhero
    Sep 18, 2023 at 20:03
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    That's a good clue. One possibility is that there's steel acoustic channel behind the plywood to reduce sound transmission. That wouldn't stop you from finding studs, but they'd probably not align with the screw pattern.
    – isherwood
    Sep 18, 2023 at 20:27

1 Answer 1

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To answer your specific questions:

Where the hell are the studs in this thing?

Use the old-fashioned stud finder: take a coat hanger wire and bend it at 90-degress. Make a hole, insert at least 10" of the wire inside of the stud cavity and turn it until it hits a stud.

If I'm mounting something <50 lbs, does it matter?

When you make the holes to insert the coat hanger, you will find out if you have plywood backing. If you do, then just use screws long enough to reach that plywood. If you find that it's only drywall, it's probably 5/8" X-type drywall. The max. stud spacing for 5/8" drywall is 24", but that's the maximum span. It's still OK to space the studs at 18", 23" or whatever, so that's probably the reason you are not finding them when trying to drill at exactly 16" or 24". But if there's drywall, there are studs. Coat hanger.

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    The stud spacing for most garage/home partition walls is 16" because the drywall on the other side is usually 1/2" (and because all other insulated walls in the home are the same).
    – isherwood
    Sep 18, 2023 at 19:58
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    You are correct.
    – Cheery
    Sep 18, 2023 at 21:27
  • It's possible to have drywall without studs of a conventional sort, but you'd probably have noticed by now if that were the case (firewalls/demising walls in "white block" ICF can be constructed with drywall directly atop the foam) Sep 19, 2023 at 4:35

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