I am building an adjustable shelf 96"x20"x12" (hxwxd) adjacent on both sides to an inside wall corner, anchored to cinder-block wall - does it need a back?

Since this will be kind of tall and slim, I will probably install a fixed shelf board in the middle to make it more stable and rigid. This shelf will will be used to store boxes with smaller tools, larger tools, etc.

It will sit 1" away from each wall because there is electrical conduit on that wall. Since it is at the top, I might choose to cut the side panels to allow them to get closer to the wall and eliminate the gap at the back.

As mentioned, I will use some furniture anti-tip brackets to make sure it is secured.

Do I need a back board for these shelves? My concern is the stability and the rigidity of the entire structure, not that things will fall through the opening in the back.

In case I decide to install a back, what is regularly used for this?

The material is 5/8 melamine, side panels predrilled.

Here is a drawing as requested in the comments. There is 1" distance between the shelf and the door.

enter image description here

Here is what I can use to secure this to the wall.

enter image description here

  • Shelves are also the 5/8" MDF? Jun 28, 2023 at 3:26
  • Yes all 5/8" melamine boards
    – MiniMe
    Jun 28, 2023 at 4:54
  • @MiniMe ah, that helps. I think if you use those L-brackets to fasten the shelf to the walls at least at the top of the shelf unit, you don't really need a back. The more brackets, the better, of course. And it would help to have some near the bottom too, just to keep the box from getting kicked or something.
    – Huesmann
    Jun 29, 2023 at 13:37
  • I alreadybiilt the thing. I added a back and fixed that in place with T50 9/16 " staples with a pneumatic stapler. That made it very sturdy. After putting thingw on the shelves the whole thibg became really haed to move it out of balance
    – MiniMe
    Jul 1, 2023 at 2:35

1 Answer 1


Something needs to provide diagonal bracing.

If the unit is going to be firmly mounted to the wall, such that the wall functions as its "back", an actual back may not be needed.

Otherwise, yes, it needs a back. Or something else which provides support against racking, which could be diagonal braces or similar solutions, but a back is often simplest, strongest, and retains options of using it to partition space if desired.

  • 1
    Simple 1/8" 'hard board', fiberboard, flooring underlayment or other thin, inexpensive, stiff material can be used for the backing. Heck all the flat-pack furniture in the world just uses stiff cardboard...
    – FreeMan
    Jun 28, 2023 at 13:37
  • @FreeMan The old cardboard never really worked all that well. I considered it cosmetic. Screws through a back cross-piece (if it had one) into the wall or add some metal brackets from the sides or top into the wall. Jun 28, 2023 at 15:49
  • 1
    I dunno @manassehkatz-Moving2Codidact... all the flat-pack stuff I've assembled over the years has all had a heavy cardboard back and I always found it sufficient. I wouldn't do that if I were making it myself, but it was fine when supplied. Maybe it's because I didn't have kids using it as a jungle gym.
    – FreeMan
    Jun 28, 2023 at 15:54
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    @FreeMan kids using it as a jungle gym That is actually the key. It is standard now to include some nearly useless (because manufacturers do the bare minimum) extra brackets/screws/straps to secure furniture to the wall, but it has not always been that way. I can't say I've always done that, but I have for many years due to the kid factor. Jun 28, 2023 at 16:04
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    I have too, @manassehkatz-Moving2Codidact. My kids are far too old to be climbing on the furniture, but they're now producing ones young enough to not know better... I've also up-rated the anti-tip brackets on some of the larger items we've installed...
    – FreeMan
    Jun 28, 2023 at 23:51

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