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