Every set of construction documents includes two halves: the drawings show what gets built, and the specifications describe the quality and performance of what gets built. But not all specifications work the same way. Architects choose from four distinct specification types, each with different implications for cost, competition, liability, and design intent.

Prescriptive specifications tell the contractor exactly what materials and methods to use. Performance specifications define the end result and let the contractor figure out how to get there. Proprietary specifications name a specific manufacturer's product. Reference standard specifications point to published industry standards like ASTM or ANSI.

Knowing when to use each type is a core PDD skill. The wrong choice can stifle competition, increase cost, shift liability in unexpected ways, or leave the design intent dangerously vague. On the ARE, you won't just be asked to define these types. You'll need to apply each one to realistic project scenarios and determine which type best serves a given set of project requirements.

This topic also covers how specification types interact with the CSI three-part SectionFormat, how they relate to the project manual, and how the choice of specification type affects coordination between drawings and specifications during the construction documentation phase.