I'm looking to install some floating shelves (I originally wrote "cabinets", sorry) in my apartment and want to put some moderately heavy things on them (likely under 100 pounds over a 48 inch long span).

I'm 95% sure there are metal studs and I can reasonably identify their location (though not necessarily their center) via my magnetic stud finder.

My only real question is how would I know which length toggle bolt to purchase?

I know I'd need 1/4 inch width bolts but I'm uncertain on the optimal length (presumably 3 or 4 inch)

Also, if the shelving bracket has 3 holes

angle brackets

should I use three toggle bolts per bracket or is that overkill (or perhaps would just weaken the drywall/stud?)?

  • I'm confused about why you'd be using angle brackets for a cabinet, which is usually mounted through its back panel or rails. Did you mean shelving? – isherwood Dec 19 '18 at 20:32
  • I was dumb - I meant shelves not cabinets – Dave84981654 Dec 19 '18 at 21:55

One does not use toggle bolts in studs. They're for hollow-wall applications and would require you to drill very large hole through the stud flange, which isn't a great idea.

It's also fairly difficult to drill the cabinet for toggle bolts, transfer the locations to the wall, drill larger holes for the togglers, insert the togglers in the cabinet, then get all the togglers into their respective holes in the wall. It's a real hullabaloo and a thing to be avoided.

Use three or four screws with sheet-metal (fine) threads in each of the available studs and you'll be fine. Since most of the pull-out force is at the top of the cabinet, you might use two screws near the top.

To answer your actual question, though, toggle bolts should usually be just long enough that, when the wings are folded back and the bolt is inserted, they can open up behind the wallboard. Whether they can be longer depends on clearance, of course.

  • Of course, you would never use toggle bolts with wooden studs. With metal studs it seems logical because they are hollow. However, if the toggle opens the "wrong" way then one side hits the stud and then the toggle doesn't open, making it basically useless. – manassehkatz-Moving 2 Codidact Dec 19 '18 at 21:11
  • perhaps just using 3 sheet metal screws in each bracket for the shelves would be sufficient? – Dave84981654 Dec 19 '18 at 22:20
  • 1
    I'll need to revise my answer, which was geared toward cabinets. – isherwood Dec 20 '18 at 2:28

You're absolutely right on using toggles. But, there's no way to know for sure what length to get without drilling at least an exploratory pilot hole to confirm the drywall thickness, if the stud's hollow (could be filled with a 2x4 or double metal studded) and that you're not going to be interfering with plumbing, electrical or communications lines.

However, the benefit of toggles is that they can be readily cut-down after the toggle's threaded-on. I normally go for 3-inch toggles and just pop them down with my bolt cutters to what I find (3/16th's toggles are done with pliers that have built-in bolt cutters...most do). Typically though, you'll be safe in most residential construction situations with 2-inch long toggles.

Finally, I'd suggest the toggle in just the top hole and sheet metal screws in the bottom 2 holes. If the stuff you'll be storing on the shelves is fragile or valuable, then I'd suggest toggles in all 3 holes...in case the weight exceeds the drywall and/or stud compression capacity and the fasteners start to tear slots down the wall.

  • thanks - this explains it intuitively better than anywhere I could find :) – Dave84981654 Dec 20 '18 at 5:02
  • Glad to help and very happy to see you staying away from any and all of the plastic garbage! – Iggy Dec 20 '18 at 6:42

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