What is the difference between a performance specification and a prescriptive specification?

• A. A performance spec states required outcomes; a prescriptive spec lists exact products and methods.
• B. A performance spec describes color choices.
• C. A prescriptive spec measures performance metrics.
• D. A prescriptive spec is only used for services.

Answer: (A)

This compares specifying outcomes you want achieved versus naming exact products and installation methods. A performance specification sets the required results and the tests or criteria to prove those results are met. It doesn’t mandate which materials or brands to use, so the contractor can choose the best means to achieve the outcome as long as the performance criteria are satisfied. A prescriptive specification, in contrast, lists specific products, materials, and installation steps to follow, leaving little room for alternatives. That contrast—outcome-focused versus method/product-focused—is why this choice is correct.

Color choices or other aesthetics aren’t the defining difference, and the prescriptive approach isn’t limited to services only.