The purpose of this paper is to study the differences between the definitions of architectural components and their representation in applications. Based on the practice and theoretical definition of construction components, the restrictions of current built-in functions in most commercial applications is addressed along with the problems encountered in modeling or recording the components. Since most CAD applications can only define simple and primitive-like objects, new definitions have to be created to describe the complexity of architectural components through pre-defined definitions, modification of definitions, or differentiation of existing definitions. Newly created definitions have to be different from old ones, supported by editing functions, and capable of performing quantity estimation. Through the exemplification of columns, beams, ceilings, wall configurations, wall openings, finishes, and room boundaries, this paper concludes that the description of components can be satisfied by the definitions created from integration, intersection, and subtraction operations. Data model for the operations is also presented.