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The convergence of CAD standards
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by Jerry Laiserin, FAIA

Cynical observers have long said that architects must love CAD standards, because we have so many of them. In an ideal world, a CAD standard would be just what the name implies: a single set of rules and procedures for documenting and conveying building design information regardless of the software used to create it or the medium in which it is viewed. But in the real world, there are multiple, overlapping standards, each of which addresses a different set of issues regarding the organization and appearance of CAD files and the sharing of information with non-CAD applications. Steady progress has been made on these fronts over the past few years [record, May 1999, pages 57–58; October 2000, pages 185–86], but the goal of a unified standard has remained out of reach—until now. Recent advances among standard-setting organizations offer renewed hope for more widespread adoption of existing standards, convergence of standards, and perhaps even unification of the various standards frameworks.


The primary players driving this integration are the National CAD Standard (NCS), produced under the auspices of the National Institute of Building Sciences (NIBS) in Washington, D.C.; and the Industry Foundation Classes (IFCs), developed by the International Alliance for Interoperability (IAI), across the Potomac River in Alexandria, Virginia. [Note: record publisher McGraw-Hill is an active participant in IAI].

Drawn and quartered

The NCS is the result of a convergence among three previously independent standard-setting efforts: the AIA’s CAD Layer Guidelines (CLG); the Construction Specification Institute’s (CSI) Uniform Drawing System (UDS); and the Department of Defense’s Tri-Services CAD Center’s plotting standards. Collectively, these components define how design files are organized internally (CLG); what goes into a drawing, how drawings are aggregated onto sheets, and sheets into sets (UDS); and how the digital components are printed or plotted.

Having the National CAD Standard built into CAD software, as shown here in ArchiCAD, automates drawing tasks such as title blocks and sheet titles, and ensures coordination and consistency of detail and sheet formats.

Version 3 of the standard will be available later this year and will include new terms, abbreviations, and layers from architecture-related disciplines such as civil engineering, piping, communications, and so forth, as well as a new administration section that clarifies many optional components for conformity to the standard. According to Alexander “Sandy” Shaw, who coordinates NCS activities for NIBS, these incremental improvements show the maturity of NCS “in the 2D organizational direction.” He adds, “We will continue to reach out to related disciplines to expand the usefulness of the 2D information; however, we’re also looking beyond 2D toward objects and the facility lifecycle information model.”

The need to advance NCS beyond drawings is echoed by Michael Tardif, Assoc. AIA, director of the AIA’s center for practice and technology. “Of course, there’s still work to be done on drawings, especially the addition of metadata in drawings that will ensure predictability of printed output regardless of the output device or setup,” he says. “But to move past drawings, NCS must develop organization and classification information for objects, which naturally pushes NCS closer to IAI and its IFCs.”

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