NCS: Common Language for CAD Users

2 May, 2012 By: Gregory L. Jordan

Version 5 of the U.S. National CAD Standard is available in an online, searchable format to further streamline collaboration at every stage of a building project.

United States National CAD Standard

For CAD-dependent firms in the fields of architecture, engineering, construction, and even facilities management, there exists a simplified, consistent approach to finding, understanding, maintaining, and sharing information in every set of drawings at every stage of the project. That approach is the U.S. National CAD Standard (NCS). Today's NCS is seamlessly integrated with building information modeling (BIM) and is available in an online, easily searchable format.

A Common Language

For many CAD users, coordinating between design and engineering firms on projects can be complicated. Individual companies typically have unique standards — an internal set of preferences that have been developed over the years that dictate how work is to be completed. Moving from one project to the next, CAD users may get confused, as every organization involved essentially speaks a different language. Moreover, on any given project, a CAD user often must coordinate across multiple software platforms and file types, piecing together details from different contributors, each with their own standard. Deciphering and translating the various approaches takes a substantial amount of time, slowing productivity and contributing to costly revisions. How much easier would it be if there were a common language for design data?

Thankfully, NCS is such a language. More than 5,000 workplaces across the country and overseas recognize NCS as the "language" of design data, just as many countries acknowledge English as the language of business.

Since 1997, professionals and companies have been using NCS to simplify their workflow. NCS is an evolving document that continues to respond to the needs of its CAD community through the National Institute of Building Sciences (NIBS) NCS Project Committee. The NIBS NCS Project Committee, the body tasked with the continued update of the existing standard, vets and approves through the NIBS NCS consensus process, input from users and industry leaders to refine the standard. This process ensures broad, democratic participation by all interested persons and organizations. It provides a framework for coordinating and integrating previously independent parts. Additionally, it establishes a mechanism for revising the constituent documents to meet the needs of the broadest possible spectrum of users.

NCS History

In 1997, building design and construction industry experts expressed the need to develop a national CAD standard. A memorandum of understanding was signed that formed a cooperative relationship for the development of the NCS. Publishing signatories, who agreed to maintain and support the continuation of the NCS, included the American Institute of Architects (AIA) , Construction Specifications Institute (CSI), National Institute of Building Sciences (NIBS), DOD Tri-Service CADD/GIS Technology Center, and the U.S. Coast Guard. Additional signees included the Sheet Metal and Air Conditioning Contractors' National Association (SMACNA) and the U.S. General Services Administration (GSA).

Today the NCS includes

  • the NIBS' Foreword, Administration Guidelines, AIA CAD Layer Guidelines, and the CSI Uniform Drawing System;
  • DWG files of the Uniform Drawing System symbols;
  • Microsoft Excel files of the AIA CAD Layer Guidelines, Uniform Drawing System terms and abbreviations, schedules and regulatory information, and tables of the plotting guidelines; and
  • appendices including the Statement of Conformance, Optional and Recommended Items, Rules of Governance, and Implementation Guidelines.


NCS Version 5

In May 2011 AIA, CSI, and NIBS released the newest edition of the standard. NCS Version 5 contains a number of refinements and additions over the previous version, which was released in 2008. The greatest improvement: Version 5 is now exclusively available in an online electronic format. Instead of storing and thumbing through a 1000-page, two-volume set, users now have a simple, bookmarked, searchable document on the Internet. Not only does this new format improve readability, it increases a firm's capacity to implement the standard and simplifies users' ability to access and share the information.

Another significant addition to NCS Version 5 is the inclusion of guidelines for implementing NCS in an organization. Laid out in an actionable, step-by-step approach, these guidelines are a tool for CAD users and managers who implement NCS, and they demonstrate to upper management that the transition to a single standard can be an easy one.

Other revisions in Version 5 are notable as well.

  • New Discipline Designators for Distributed Energy and for Real Estate (a new Level 2 resource) and an expanded Discipline Designator for Survey/Mapping.
  • New layers for additional structures, wind and solar power, fire ratings, air barriers, architectural curtain walls, and electrical cathode protection.
  • New and revised symbols for interior elevation indicators, azimuth indicators, architectural scale, electrical, and more.

Benefits for CAD and BIM Users

Just as English is not specific to one country, NCS is not specific to one discipline. CAD users in architecture, engineering, surveying, construction and development, and even facilities management can adopt, understand, and apply NCS. The consistency of a single standard provides common terms, symbology, and naming conventions across the board; information appears in the same place in all drawing sets, so translation between formats is predictable; and time for file formatting and error checking is reduced.

With the standard in place, a user doesn't have to think about what this line indicates or what that symbol represents. Rather, everyone from the designer to the facilities manager can find, understand, and maintain the information in every set of drawings at every stage of the project. For example, the surveyor can input initial data, the architect can layer in the conceptual and final designs, and the engineer can fill in the building design details — all in the same set of plans. Because of a common understandable standard, all these elements can be isolated or displayed easily at the designer's discretion. Out in the field, the construction crew can confidently translate the information to build the project. After construction is complete, the facilities manager can use the same set of plans to perform FM functions.

NCS is, and will continue to be, a key element of the language of design, especially with the widespread adoption of building information modeling (BIM). Although BIM's 3D capabilities can be invaluable, designers and engineers still need a reliable method to communicate information to people in the field. The best method is to apply NCS to the printed output of the building model; in fact, one of the greatest benefits of NCS is its seamless integration with BIM. Some members of NIBS' buildingSMART alliance serve on both the NCS and the National BIM Standard (NBIMS) project committees. NCS provides designers and engineers with an understandable method to communicate the detailed, 3D information from BIM to the people in the field.

If you're already using NCS, you may be interested to know that the next NCS revision cycle is planned to start in early summer 2012. Anyone owning a copy of NCS can apply to join the NCS Project Committee and participate in the revision process. All you need to do is demonstrate that you own a copy of Version 5 and submit a NIBS/buildingSMART alliance application.

About the Author: Gregory L. Jordan

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