Installing a shelf in your home or apartment is a popular home repair project that seems simple until you try to install one. In order to avoid sagging shelves you need to know the relative span limitations of different shelving materials. And don't forget to use the proper wall anchors.
The span limit is the MAXIMUM distance you can place the shelving supports. Glass, particle board, lumber, plywood and other shelving material options can have span limitations between supports ranging from 18” to almost 5 feet! Books are usually the heaviest items you’ll put across the shelves so knowing the basic span capabilities of your shelving material when supporting books is useful so your shelving is not, well, overextended.
The following information will identify recommended shelving spans and also the recommended height or distance between shelves for common storage items such as books and media.