First step: 2D Plan
The 2D plan is created using 2D (or 3D) CAD or CADD ("Computer-Aided Design and (or) Drafting") software. Drawing entities are created in this program which represent construction assemblies. Colors are used either for clarity in presentation or for the convenience of the operator in identifying and organizing entities, line weights, and other properties.

Lines and entities are placed in separate logical "layers," or independently accessible storage areas within the program which can be displayed and worked on either independently of other layers, with other layers, or not at all. This advance in designing and creating illustrative drawings has made coordination of construction assemblies considerably easier than was - and is - the case with manual drafting.

In addition to drawing, CAD systems have the potential to store building-related information in association with the drawn lines. Examples include lists and quantities of materials represented by the lines, labor required to erect the assemblies, thermal characteristics of the assemblies, and links to information about other building systems, to name a few.

Next: Creating the Wireframe.