Abstract: An add-on shelf has a pair of legs at least one of which having a locking structure that is configured to removably lock the leg to an existing structure and a support structure that supports a shelf deck. A void space is positioned between the legs, shelf deck, and existing structure. Alternatively, a width adjustable storage apparatus has first and second sections operable to engage each other in a plurality of adjustable positions each corresponding to a different width of a shelf surface formed by the sections, and first and second supports that engage an existing structure for supporting the first and second sections. The shelf surface is positioned in a generally horizontal plane and the first and second sections do not extend above that generally horizontal plane.