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

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

• A. A prescriptive specification states desired outcomes with criteria; a performance specification provides fixed materials and methods.
• B. A performance specification requires exact product brand.
• C. A prescriptive specification defines outcomes and criteria; a performance specification fixes materials.
• D. There is no difference between the two types.

Answer: (C)

Performance specifications focus on what the finished work must achieve—the required outcomes and the criteria by which success will be measured—without naming specific products or installation methods. This lets the contractor choose materials and construction approaches that meet the performance targets, with verification through tests, calculations, or performance data. Prescriptive specifications, on the other hand, specify exactly which products, materials, and installation procedures must be used. They define the inputs and methods, leaving little room for substitution, which can simplify quality control and risk for the owner but reduce flexibility and potential cost savings. So, the key difference is outcomes and criteria versus fixed materials and methods. This means performance specs allow flexibility to meet the goals, while prescriptive specs dictate the exact means to achieve them.

Performance specifications focus on what the finished work must achieve—the required outcomes and the criteria by which success will be measured—without naming specific products or installation methods. This lets the contractor choose materials and construction approaches that meet the performance targets, with verification through tests, calculations, or performance data.

Prescriptive specifications, on the other hand, specify exactly which products, materials, and installation procedures must be used. They define the inputs and methods, leaving little room for substitution, which can simplify quality control and risk for the owner but reduce flexibility and potential cost savings.

So, the key difference is outcomes and criteria versus fixed materials and methods. This means performance specs allow flexibility to meet the goals, while prescriptive specs dictate the exact means to achieve them.