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Proprietary Specifying 102 - Descriptive Specifying in Proprietary Specifications

By Kevin O'Beirne, PE, FCSI, CCS, CCCA, CDT posted 08-12-2019 16:46


Editor's Note: CSI is pleased to publish this second blog from Kevin O’Beirne, PE, FCSI, CCS, CCCA If you have an idea or opinion you would like to share with your colleagues in the construction industry, please contact CSI Content Strategist Peter Kray at He would love to help publish your thoughts.

Many specifications sections include more than one method of specifying: descriptive, proprietary, performance, and reference standard specifying. Proprietary specifying—indicating manufacturers and products by name in the specifications (i.e., “Provide Model A by Manufacturer X, or Model B by Manufacturer Y”)—can be very useful and powerful. However, it also poses special challenges for the specifier. This blog post addresses how much descriptive specifying is appropriate in conjunction with proprietary specifying.

Descriptive specifying is when detailed, descriptive requirements are indicated. When the specifications rely on proprietary specifying, the extent of descriptive specifying should be limited, especially in closed-proprietary or sole-sourced specifications.

After all, the acceptable products and manufacturers have already been indicated and piling on unnecessary descriptive requirements is likely to:

  1. Create conflicting requirements, which could come back to haunt the design professional and owner during construction; or
  2. Prompt higher prices bid to the owner when descriptive requirements mandate products that are not the manufacturer’s standard items; or
  3. Result in construction stage disagreements, change proposals, or claims if the design professional attempts to enforce a requirement for the manufacturer to furnish an unusual permutation of the standard product.

The following true example illustrates the point: Before hiring an engineering consultant about 12 years ago, a project owner selected specific, unique, major equipment for its facility improvement project.  The engineer (not the author’s employer) was retained on the proviso that the selected equipment was the basis of the design, so the engineer had no role in evaluating or selecting the equipment but, naturally, coordinated closely with the selected manufacturer when preparing the drawings and specifications. The sole-sourced equipment was to be purchased and installed by a contractor, under design-bid-build project delivery.

Despite the equipment being sole-sourced, the engineer-drafted equipment specifications included approximately 15 pages of very-detailed, descriptive requirements, in addition to various performance and reference standard requirements. The equipment was procured, shop drawings were approved, and the items were installed and started up. 

During early stages of operation, an extreme condition, nevertheless within the equipment’s design parameters, occurred in which the equipment failed. The owner’s facility operations were interrupted, understandably causing great consternation and recriminations. It took months to identify the cause of the failure.

It was found that the equipment furnished was the largest the manufacturer had ever produced, and the manufacturer and its sub-supplier had little experience with equipment of that size. Certain, two-horsepower drive motors should have been a three-horsepower. There were approximately 12 identical main equipment items and each had multiple drive motors. The cost to remedy all the equipment was substantial and the irritated owner asserted that it would not pay for the remedy. In the end, the sub-supplier, manufacturer, and engineer paid the cost; the engineer’s share was $250,000. Why?

The engineer’s specifications sole-sourced the equipment to the desired manufacturer, but inclusion of approximately 15 pages of detailed, descriptive requirements later cost the engineer dearly. The specifications explicitly required two-horsepower drive motors, which ultimately proved inadequate.  The motor size had been recommended to the engineer during design by the manufacturer.

Had the engineer significantly reduced or eliminated the descriptive language, the owner would still have received the desired, sole-sourced equipment but the onus for furnishing properly operating equipment would have resided squarely with the manufacturer. The engineer would have saved $250,000.

Thus, when using proprietary specifying, include only enough descriptive language needed to obtain the required work results. For example, descriptive specifying may be necessary to properly set forth requirements for desired options not normally furnished with the basic product.

When using proprietary specifying, the onus is on the specifier to ensure that the manufacturers whose products are indicated in the specifications are capable of fully complying with the required descriptive requirements, performance criteria, and specified reference standards.

The moral of this story is that longer specifications are not necessarily better. Specifiers should clearly understand the four methods of specifying and know when, and when not, to use each.

Copyright 2019 by Kevin O’Beirne.  Used by CSI with the author’s permission.

The content of this blog post is solely the author’s work and should not be attributed to any other individual or entity.


Kevin O’Beirne, PE, FCSI, CCS, CCCA is a professional engineer licensed in NY and PA with over 30 years of experience designing and constructing water and wastewater infrastructure for public and private clients.  He is the National Manager of Engineering Specifications for HDR, a global engineering and architecture design firm.  He is a member of CSI’s MasterFormat Maintenance Task Team and is the certification chair of CSI’s Buffalo-Western New York Chapter.  He is an ACEC voting delegate on the Engineers Joint Contract Documents Committee (EJCDC) and lives and works in the Buffalo NY area. Contact: