top of page

What's the Difference Between CAD, CADD, and BIM?

As design professionals, we’re occasionally asked how everything happens behind the scenes and what tools we utilize to deliver results. Everyone will give you a different answer depending on where they fall in the spectrum of concept, design, production, and delivery, but there will inevitably be the utilization of one of a few tools.   


In 2024 we’re not hand drawing beyond a certain point in the process. Most of us start with hand sketches and then transition to the computer as information starts to solidify into quantifiable criteria. Depending on the level of complication, integration of other disciplines, and industry standards, we often utilize a suite of programs that talk to one another in various capacities, each refined for an individual workflow. They all have some basics in common, but diverge quickly in their capabilities, interface, and output options; some of which may not necessarily be needed for a project.


Let’s break down the acronyms off the top. The big three are CAD, CADD (yes, they are different), and BIM. Each adds layers of capabilities on top of a baseline for precise illustration and reproduction capabilities at scale, to ensure that design intent is properly documented and conveyed. Note that these examples are for architectural systems, but similar ones would apply for structural, mechanical, or electrical engineering.


Computer Aided Drafting (CAD)

CAD is the grandfather of them all, utilizing a computer to provide precise drawings that can be scaled and transferred between systems. The trick here is that CAD is manual input, meaning that there isn’t assistance from the computer software to extrapolate intent or add data to a file. CAD can be 2D or 3D, but is a highly manual process of computer design. Think of it as digital paper and pen, easy to send and reproduce, but each line or mass must be put there manually by a person. A door, for example, is just a bunch of lines. The program doesn’t realize that as a whole it’s supposed to be understood as a door.


Computer Aided Drafting and Design (CADD)

The extra “D” makes a big difference in representing the capability of the programs that are utilized. This means that the software is tailored to our industry and provides additional capability besides the simple creation of lines. Looking at our door analogy, when creating the door, there is more data in the program; it knows that it is supposed to be a door. It also is considering what kind of door: wide, tall, which way it swings, etc., more like building with a kit of parts than just lines. The same goes for the other components, typically appearing in 3D and enabling more data to be generated at a faster rate than drawing/modeling individual pieces line by line.


BIM = Building Information Modeling

BIM is a completely different approach and is a platform which is customized for creating/coordinating building systems in a manner that includes detailed information about each component’s construction, assembly, finish, etc. into the model itself. This is the “I” in BIM and what makes the software so powerful is the amount of information which is embedded into the 3D model that is generated. In a BIM model, a door can contain a great deal of information. Adding to what’s already in a CADD model (size, finish, swing, etc.), the information of a true BIM model will include the room, hardware, key type, fire rating, hinge, warranty, and so on. All of the information that you could want to know about that door can be coded into the model for coordination of construction, building maintenance, and facility planning purposes.


The amount of information contained in a BIM model varies widely, depending on how much is being coordinated through the model. On your typical house or small commercial project, there probably isn’t a great deal of advantage to having a highly intelligent BIM model, as it does take a good deal of work to input that data. On the other hand, when you consider a project like a hospital, where there are hundreds of systems, all of which need to be coordinated and maintained, BIM is an indispensable tool to the industry from concept through construction.  


Related Posts

See All


bottom of page