The main consideration in stacking is to achieve economy of space while ensuring ease of accessibility for the readers to the contents of the shelves. Space is at a premium in almost all libraries and the problem of space is faced by libraries with a large and growing collection. Solutions for this problem are found in the different methods of stacking.
Double Rows on Fixed Shelves
In this method, you can arrange books in double rows on normal fixed shelves. While this increases capacity, it hinders access to the rear row. A modification of this is to use two separate shelves for ‘two layers' with the facility to swing one layer to the side to have access to the rear row.
In this method two shelves are joined together with hinges at one side. One shelf is fixed, while the other is mounted in front of it at the hinges. In this system, the whole shelf can be opened as a door to reach the books on the rear shelf In order to facilitate the operation of the hinged shelf a roller is attached to the bottom edge, running on a curved metal rack on the floor.
These are metal stack units mounted on ball bearing wheels which are placed side by side. The ball bearing wheels help the individual units to roll easily when they are pulled aside.
This method has been adopted by many large libraries throughout the world to solve the space problems particularly in the past. It consists of wooden stacks, supported by metal framework extending from basement to the roof. The load of books and shelves rests on the basement which has a strong foundation to bear the load. The vertical extension of stacks is economical than the horizontal one in this method as the floor on each stack is a temporary one, which may be either a wooden framework or a lighter steel or concrete framework.