2

I bought some shelf brackets. They are the same length on both sides, and both sides have three screw holes. However the screw holes on one of the sides are not in a straight line.

Here's 2 photos:

Straight Wonky

Why are they slightly offset, and which side should go to the wall?

0

3 Answers 3

1

I believe freeman has it backwards. The screws in line are for attaching to the studs. The 2 at the top create the strength or ability to resist pullout While also in conjunction with the 3rd provide the lateral support to handle the weight.

The offset spacing would be to hold the shelf board / plank in place.

I have put up many homes shelving this way and believe it to be accurate. You want your fasteners in the center of the stud.

7
  • No. Shelf brackets nearly always have a longer horizontal leg. This puts the staggered holes on the wall. Evidence
    – isherwood
    Sep 3, 2021 at 20:51
  • I'm pretty sure you are correct! I found this out when I realised that the holes in a line are actually bigger than the holes at the top. I bought some pretty hefty bolts (these brackets are for a 40cm wide shelf!) and it turns out they only fit into the holes that were in a line. The difference was small, but enough that they wouldn't go in the wonky holes. Now, smaller bolts would have gone in both, but I am guessing bigger holes for bigger screws to go into the wall. Thanks!
    – NibblyPig
    Sep 3, 2021 at 20:52
  • @isherwood I agree, however in this case both legs are identical in length.
    – NibblyPig
    Sep 3, 2021 at 20:53
  • Strange. Anyway, the three screws would go into the wall. That's where you need the most pullout strength.
    – isherwood
    Sep 3, 2021 at 20:54
  • If you look at the pics, both legs have 3 screws. I've always installed them with the offset holes on the vertical and my wife has always severely overloaded the shelves and I've never had one fall. Long story short, it probably doesn't really matter much which way they go.
    – FreeMan
    Sep 3, 2021 at 22:08
1

The side in the top pic has the two holes closer together and centered. This is the "up" side - the shelf will sit on this. The side in the bottom pic has them offset and farther apart, this is the wall side.

On the shelf side, they're closer together because these are simply to keep the shelf from slipping off the bracket and to tie the brackets together with the shelf to keep the whole thing from wobbling side to side.

On the shelf side, they don't need to be offset because:

  • Shelves will either be particle board with no grain to split, or
  • Real wood, but these go cross-grain so the two of them cannot get into the same growth ring, so there's limited ability for them to cause a split.
  • You use short screws to go into the fairly thin shelf, so there's more room for screw & driver before you hit the angled brace
  • You probably don't actually need to use screws into the shelf in all 3 holes. Use the one closest to the wall and the one at the end. Put the 3rd screw in if you're feeling ambitious.

On the wall side, they're offset for a couple of reasons:

  • So that both screws don't end up in the same growth ring of the wall stud. This decreases the chance of the wood splitting

  • So that you can get a screw & driver straight up into the hole instead of driving it at an angle.

    If you notice, that screw by your pointer finger (2nd pic) would be hard to get a long screw plus screwdriver into the space between the bracket and the angled brace if it were centered.

    Driving them straight helps ensure each screw is fully embedded in the wood (instead of possibly blowing out the side).

    Having the screwdriver straight on to the screw prevents it from slipping out of the screw head and stripping it.

1
  • This is right. I was initially confused by the "closer together" thing in the first paragraph, so I wrote an answer. Now I see that we agree.
    – isherwood
    Sep 3, 2021 at 21:04
0

I realize now that FreeMan's answer is basically the same. I'll leave this here as additional info, but he's right.


While the bracket could be used in either orientation, unless you're carrying extremely heavy loads the longer leg goes on the horizontal. This is to provide more shelf depth with less intrusion into the space below. It's also adequate for most loads. You might do the reverse to make the diagonal brace more vertical for max-load situations. (I've learned that the legs are of equal length in the case above. Read on.)

Also, the offset holes are in pairs for greater holding strength. Most brackets have just two on the horizontal leg, but three on the vertical. Since the most pullout force occurs near the top of the vertical, extra fastener holes are provided. Countless product photos testify to this fact.

The holes are offset for two reasons:

  • Because putting two large fasteners into a single framing member on the same vertical line could result in cracking, and therefore reduced holding power.
  • Because it's difficult to get a drill or driver in behind the diagonal bar, so you'd be required to either tilt the fastener to the side or tilt the drive tool with respect to the fastener. Neither are ideal. This is less of an issue for the small screws used to fasten the shelf to the bracket.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.