Bookcase Shelves That Do Not Sag

Step 6 The Bookcase

So, here's the style of bookcase I've been making and using for about 20 years. There's really not much to it beyond what we've already covered. A couple of upright 2X4 posts go on each end, and the shelves tie into them with some very simple slotted joinery. Basically, the rear slotted 2X4 is 1 1/2" shorter than the shelf, and the shelf is supported by 3/4" deep slots on each of the four 2X4 posts.

Note that you don't really need any fasteners for any of this, although I've sometimes used a few screws primarily to help hold things tight while glue is drying. Screws are really only effective when the thread is holding in a piece of 2X, not particle board. I glue the shelves into the post slots, but bolts could be used instead to allow disassembly.

If you're paranoid, or you're making a workbench which is significantly deeper than a shelf, or you just feel like it, simply add a 2X2 front support which is 1 1/2" longer than the particle board, and set it into the 2X4 side posts as shown in the first figure. The second figure shows a close-up of the bookcase shown at the start of this Instructable -- which uses a 2X4 in the front, but doesn't have it set into the posts.

This general approach also can work replacing the particle board with other sheet construction materials such as plywood or OSB. The texture of the finish is not as nice using OSB.