In general, good air circulation should be maintained in storage areas. They should be stored three inches away from walls to allow air circulation.
Books should be arranged so that shelves are full, but not so tight as to cause damage when they are removed. Bookends should always be used for shelves that are not full. Shelving should be wide enough so that books do not extend beyond the edges. As a rule, books should not be stacked in piles on shelves.
At the same time, books on shelves should be kept even with each other on the shelves and not in a ragged, haphazard, or "any old way" fashion -- even if shelved upright and with bookends.
Most bindings are weakest at the joint or hinge area. When a book is shelved fore edge down (two pictures below), gravity will eventually and inevitably pull the text block from the case at the hinge.
Library bookcases should be constructed of steel with a baked enamel finish. Wooden shelves should never be used because of the possibility of the wood outgassing harmful compounds. The shelves should be smooth and solid, without rungs or slots, and free of jagged edges and protruding screws. The bottom shelf should be no less than four inches above the flooring order to avoid problems from rising water and splashes from cleaning.
Books should rest vertically on the shelf so they are supported by other books or a bookend. Books should be upright on shelves, and not allowed to lean to one side or the other.
A user may remove a book from the shelf and then try to re-shelve later and not find a space -- or is unsure of the correct space. Volumes should not be left on top of each other or on top of other upright volumes. These situations are potentially harmful to books. If you see these kinds of situations, please correct them.
Bookends should also be made of steel, with a baked enamel finish. They should be free of sharp edges and rust, and high enough to support over half the height of the book. Wire bookends that hang from the shelf above should be avoided, because books tend to slip under them and slide into a leaning position. Take care to avoid knifing the text of the book (shown below).