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Looking for a sanity check

Could one mount an articulating arm to 25 gauge metal stud behind 3/4" drywall using a toggle bolt instead of lag bolts into wood/concrete?

Load is 13lbs., arm itself is about 6lbs., max extension is about 25" (would use to about 12").

Details

This articulated arm wall mount is intended to be screwed into a wood or concrete stud using two 3.1 inch / 80mm lag bolts (thread length 2 inch).

After drilling the first hole I discovered it's a metal stud, not concrete / wood beneath 3/4" drywall.

I was resigned to give up right there, but wanted a second (or third) opinion.

Would a 1/4" snap toggle anchor (PDF performance data) secured to the metal stud under 3/4" drywall provide roughly the same performance? Toggler claims 464 lbs. pull-out load on 1/4" thread fastener.

The American Wood Council notes a 2" thread lag screw into Spruce-Fir-Pine (softest wood) resists pull-out load of about 319 lbs. I see roughly similar numbers elsewhere.

Am I thinking about this the right way or overlooking something that will end up in disasterland?

Thanks.

wall mount lag bolts instructions

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  • 3/4" drywall isn't generally a thing. You probably have 5/8".
    – isherwood
    Commented Dec 7, 2021 at 15:00

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Point focused loads going into metal studs are not a good idea. You would be much better advised to install a piece of good quality 3/4" plywood to the wall that is big enough to span across two or three studs and have a height of about one stud spacing. Use multiple sheet metal stud screws to secure this plywood to the wall. Then you can install the bracket to this plywood with short large sized screws. If you drill proper sized pilot holes for the screws into the plywood they will have remarkable holding power. (You would not use those lag bolts that came with that bracket).

Note that the surface of the plywood will be a far better bearing surface for the bracket as well. If you installed the bracket directly against drywall there is a good chance that over time the stresses on the bracket back and forth will dig into the drywall and cause degradation of the wall surface and let the bracket get loose.

If good quality plywood is used it can be nicely sanded and painted to match the wall. It will be hardly noticeable behind the monitor.

If you have concern with the bracket screws just into 3/4" plywood you can always use the toggler bolts to hold the bracket to the plywood.

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    I agree the metal stud could support a static load non articulating. But moving the arm side to side there is not much support other than the sheetrock. Spaning 2 studs with plywood would be much less risk that it will flex the wall. I have done this trimmed and painted the plywood to be an accent piece much like a picture frame behind the tv looks good and friends have commented on it.
    – Ed Beal
    Commented Feb 21, 2018 at 14:55

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