What Is CAD? What Is BIM?

Computer Software Applications for Architects and Builders

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What's Next in Computer Design?. Photo by Sean Gallup / Getty Images News / Getty Images (cropped)

The letters CAD stand for computer-aided design. The letters BIM stand for Building Information Modeling. Architects, drafters, engineers, and artists use various types of software to create plans, construction drawings, precise lists of building materials, and even instructions on how to put together the parts. The first two letters of each acronym define the software and their derivatives. CA- is computer-aided software for many design projects, including computer-aided engineering (CAE) and computer-aided three-dimensional interactive application (CATIA).

BI- is all about building information. CAD and BIM are usually pronounced like words.

Hundreds of years ago, structures were built with no written plans or documentation. Before the age of computers, drawings and blueprints were drafted by hand—a process that begat the "change order." CAD and BIM are more efficient because the software records lines as vectors based on mathematical equations. Using the algorithms or set of directions that drive the software, portions of a drawing can be twisted, stretched, or moved. The picture as a whole will automatically adjust in 2D, 3D, and 4D.

About CAD:

CAD Software will let the designer:

  • Switch between two-dimensional (2D) and three-dimensional (3D) views.
  • Zoom in and out for close-up and distant views.
  • Rotate images to view them from different perspectives.
  • Change the scale of images: When one value changes, related values are automatically adjusted.
  • Manipulate the shape of images: Changing one portion of an image automatically changes the entire picture.

    CAD is also known as CADD, which stands for Computer-Aided Design & Drafting

    Examples of CAD Products:

    Popular CAD programs used by architects, engineers, and home designers include:

    Simplified versions of CAD tools can be found in home design software tailored for non-professionals.

    About BIM:

    Many building and design professionals are moving from CAD to BIM or Building Information Modeling applications because of its advanced capabilities for parametric modeling. All components of built structures have "information." For example, imagine a "2-by-4." You visualize the component because of its information. A computer can do this for thousands of components, so an architect can easily change a design model by changing the information that makes up the design. After a design is complete, the BIM application lists the component parts for the builder to put together. BIM software not only digitally represents the physical, but also the functional aspects of a building. Combined with file-sharing and collaboration software ("cloud computing"), BIM files can be tweaked and updated across all parties in the project—sectors of the Architecture, Engineering and Construction (AEC) Industry.

    Some call the process Smart Geometery. Some call the process 4D BIM. In addition to the length, width, and depth dimensions, the fourth dimension (4D) is time. BIM software can track a project through time as well as the three spacial dimensions. Its "clash detection" abilities red-flag system conflicts before construction begins.

    Some call BIM "CAD on steroids," because it can do what 3D CAD can do and more. Its most common use is in commercial construction. If a project is very complicated (for example, the Transportation Hub in Lower Manhattan), more complicated software is often used in order to save money in the form of time and effort. But the Transportation Hub in New York City is famously over budget by millions of dollars. So, why doesn't BIM always save money for the consumer? Saved money on design can be moved into more expensive construction materials (why not use marble?) or overtime pay to hurry the pace of construction. It can also line the pockets and coffers of other projects, but that's another story.

    BIM has Changed the Way We Work:

    This change in software use also demonstrates a philosophical change in doing business—from paper-based, proprietary ways (the CAD approach) to collaborative, information-based operations (the BIM approach).

    Construction law attorneys, such as Thomas L. Rosenberg of Roetzel & Andress, have addressed many of the legal concerns surrounding an inclusive, shared process of design and construction (see the PDF document "Building Information Modeling" (2009). Issues of risk and liability should be clearly defined in any contract where information is shared and design drawings can be freely manipulated.

    Examples of BIM Products:

    CAD and BIM Standards in the United States:

    The buildingSMART alliance,™ a council of the National Institute of Building Sciences, develops and publishes consensus-based standards for both CAD and BIM. Standards help the many groups involved in building projects to more easily share information.

    Help Deciding:

    Change is difficult. It was laborious for the ancient Greeks to write down their temple plans. It was frightening for human drafting machines to sit next to the first personal computer. It was awkward for the CAD specialists to learn BIM from the intern right out of architecture school. Many companies make changes during construction slowdowns, when "billable hours" are few and far between. But this everyone knows—many commercial projects begin with a competition and are put out to bid, and a competitive edge becomes more difficult without change.


    Computer software is complicated even for the technically savvy architect. Private companies have grown up around these complications, with the aim of helping small businesses and corporations buy the appropriate software for their needs. Companies like the online Capterra will help you for free in a business model similar to travel agents helping you for free. "Capterra's service is free for anybody looking for business software because software vendors pay us when we help you find the best match." A good deal, if you trust and respect your consultant and know what you're getting into. Check out the Top Architecture Software Products from Capterra.

    Source: Capterra website accessed February 11, 2015.

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    Your Citation
    Craven, Jackie. "What Is CAD? What Is BIM?" ThoughtCo, Jan. 26, 2017, thoughtco.com/what-is-cad-or-bim-178399. Craven, Jackie. (2017, January 26). What Is CAD? What Is BIM? Retrieved from https://www.thoughtco.com/what-is-cad-or-bim-178399 Craven, Jackie. "What Is CAD? What Is BIM?" ThoughtCo. https://www.thoughtco.com/what-is-cad-or-bim-178399 (accessed May 28, 2018).