What type of specification provides the criteria that the contractor must build to but does not include a specific design?

A performance specification outlines the desired outcomes or functionality that a contractor must achieve while allowing flexibility in how those results are realized. This approach focuses on the "what" rather than the "how," meaning it specifies the performance requirements without dictating the exact design or materials to be used. Therefore, the contractor has the autonomy to determine the methods and materials that will meet the specified performance criteria. This type of specification is particularly useful in projects where innovation or specific solutions suited to unique challenges are desired.

In contrast, other types of specifications may impose specific requirements regarding design, methods, or materials. A prescriptive specification, for example, provides detailed instructions about how to achieve the desired outcomes, which can limit the contractor's options. Project specifications generally encompass a range of details including both performance and prescriptive elements but do not uniquely focus on the flexibility in design that performance specifications allow. Preliminary specifications are often used in the initial phases of a project and may not provide the detailed criteria that performance specifications offer.