Adding more space to an existing building is an important decision for even the most experienced building owner or facility manager. New construction or building modifications are two common solutions, but structural steel mezzanines offer a third alternative at potentially less cost and in less time.This paper is designed to help building owners and facility managers to determine if a mezzanine is appropriate for their specific need, and to cover the primary considerations that must be addressed in selecting and designing the best mezzanine solution for that need.