Descriptive vs Prescriptive Specifications

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Lauren Craig

August 30, 2023 00:59

Doing some research on the different types of specifications and I came across both Descriptive AND Prescriptive construction specifications. From my understanding, these two are essentially the same thing, right? I know the other types are proprietary, performance, and reference and I understand how those are all unique, but I'm struggling with Descriptive vs Prescriptive. Thank you in advance!

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  mariesamek August 30, 2023 12:03

  Hi Lauren,

  According to the CSI Practice Handbook, Descriptive and Proprietary specifications are both types of Prescriptive specifications. Prescriptive specs provide the means to achieve the desired results (either by way of a describing them or by naming proprietary products that have the desired characteristics), whereas performance specs specify the results and not the means to achieve them. CSI PH gives an example to differentiate between the two: Specifying a "non-sag" ceiling hanger is using performance specifying, while saying "straightened No. 11 wire, tightly wrapped two times" is using descriptive specifying. 

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  lyfian0924 September 01, 2025 13:43

  Hi Lauren, I'm confirming if there is a typo. Did you want to say "Descriptive (not prescriptive) specs provide the means to achieve the desired results"? 

   

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  jgo1999 April 01, 2026 22:34

  Hi, from my understanding the difference is this: 

  Prescriptive: details the means and methods of construction, steps of installation etc. while also listing a specified manufacturer?

  Descriptive: details the means and methods still but does NOT list a specified manufacturer.

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  anthonypriest April 01, 2026 22:37

  The only primary difference is descriptive requires someone to write what the specification entails. It may it may not include manufacturers

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  kkgalicinao April 03, 2026 19:09 (Edited April 03, 2026 19:10)

  Lauren Craig jgo1999 great question! Descriptive and prescriptive specs are actually pretty different. Prescriptive specifications typically name specific materials, products, or even approved manufacturers that must be used. Descriptive specifications focus more on describing the required characteristics, materials, and workmanship; basically outlining what the end result should be without necessarily naming a specific product or brand.

  Hope this helps!

  Kiara | Black Spectacles | Community

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