Shelving for furniture and built-in fitments is often installed simply supported at the ends only and deflection can be excessive if spans and board thickness are not related to expected loading.

Shelving that is continuous over two or more spans provides an efficient construction. So too is the provision of support at the back of the shelf. Shelving supporting mixed goods such as linen or kitchen ware is not as heavily loaded as book shelves. Books need special consideration because they pack together tightly and impose high distributed loads. Some books, such as paperbacks may only load half the shelf depth while others of A4 size, may load the full shelf depth. All these points should be considered when designing bookshelves and selecting board thickness, shelf span and shelf support details. As a guide the following recommendations are made for maximum shelf spans:

Shelving supporting miscellaneous items or small books (ie. not extending over full shelf depth)

Loading over full shelf depth (eg. A4 books)