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A Comparison between CAD and BIM

Don’t use CAD and BIM as Interchangeable Phrases

Computer-aided design (CAD) has been a focus of the architectural sector for many years. It allows you to design accurate floorplans and models, which you can use to impress your clients.

However, the industry has evolved over the years. New concepts get introduced regularly, which means CAD is no longer all you need to think about when presenting to clients.

Building Information Modelling (BIM) is one of those new concepts. Its focus on creating sustainable buildings and collaborative environments has proven important in the industry. The rise of cloud computing has only fuelled BIM’s rise.

Even so, many people confuse the two terms. There is a relationship between CAD and BIM. However, they aren’t the same thing. BIM is not just 3D modelling, which is something that many people forget. Instead, it is a philosophy that you have to commit to if you’re going to get the most out of it.

To do that, you need to know the difference between CAD and BIM. You also need to know how each applies to the current architectural industry. This article will help you to understand both.


What is CAD?


As mentioned, CAD is short for computer-aided design. As the name implies, it involves the use of computers to help you to create designs and documents related to your projects. You will use CAD for large projects. It allows you to bring several designs together, so you can fit them into a larger unit.

CAD software originally allowed you to create 2D drawings, such as floor plans. However, the software packages have evolved in recent years. Today, many people use CAD to create full 3D models that offer more accurate representations of their ideas.

This transition into 3D has been transformative for architecture. It allows for the creation of extremely complex models. Furthermore, clients can use these models to understand the work of their designers. CAD has sped up the industry. Today, designs can go from concept to manufacture much quicker than in the past.


What is BIM?


Many see Building Information Modelling as the natural evolution of CAD. What BIM is not is a type of CAD package. Instead, it’s a design methodology that you can use independently of CAD. However, most use CAD as part of the BIM method.

Two things lie at the heart of BIM: collaboration and sustainability. BIM allows you to bring all your designs, including CAD models, into a single database. Using the cloud, BIM provides access to this database to all project members. You’ll all work on the same models, which allows for quick changes as needed. When used correctly, BIM helps the entire team visualise the project. In fact, this is one of the main benefits of BIM in construction. The team can spot project issues before construction even starts.

That’s because of the sustainability aspect of BIM. The methodology allows you to design every aspect of a building. In addition to the building itself, BIM models feature electrical wiring and other important aspects of design. This creates a more realistic digital representation of the final product.

You might think of BIM as the bridge between CAD and construction. When used correctly, BIM can expand on your basic CAD designs, providing more information to project stakeholders in the process. That’s a simplification of the relationship between CAD and BIM. However, it’s still valid.


CAD Advantages and Disadvantages

CAD has played such a huge role in the engineering and architectural sectors for several reasons. It still stands as one of the most useful technologies available. However, it isn’t perfect. Let’s now look at some of the advantages and disadvantages of CAD.


The Advantages

CAD advantages include all of the following:

  • It’s easy to use compared to the clay and paper-based modelling techniques that it replaced. The best CAD software packages offer all the tools that novices need to create basic 2D and 3D models.
  • Recent CAD software incorporates a host of features. Advanced users can use these features to create extremely complex models.
  • CAD software can help you spot errors. If you can’t get something to fit together in CAD, you probably won’t be able to in real life either. This makes CAD a valuable learning tool for student, architects, and engineers.
  • Many CAD packages create documentation for you. Anything you design has a paper trail attached. This is very useful for complex projects because you always have something to refer back to when needed.


The Disadvantages

As mentioned, CAD isn’t perfect. It has the following disadvantages:

  • The ease of CAD can make its users complacent. With so many tools at your disposal, it’s easy to slip into just using whatever’s in the software’s library. This can lead to your designs looking similar, which could cause issues if you provide regular work to the same client.
  • CAD allows you to pull parts together without considering any real-world issues. In reality, such parts need to be welded or fastened. It’s easy to forget the work that goes into this when building a CAD model.
  • Even with their ease of use, CAD software does have a learning curve. You’ll need to scale that curve to get the most out of the software. Failure to do so results in basic designs that pale in comparison to those of your competitors.


BIM Advantages and Disadvantages

Though many in the industry have switched to Business Information Modelling, it’s still not perfect. BIM comes with its own pros and cons, so let’s look at them here.




There are several BIM advantages, including the following:

  • BIM offers a more complete representation of a building’s design. It takes more than the building’s core components into account. For example, BIM allows you to design electrical and HVAC systems, as well as the building itself. This means the project team can take full advantage of the space and resources available.
  • BIM pulls your documents into a single database. Several people can work on the same model and save it to the cloud. This allows for instant updates, so you won’t waste time searching for documents when you need to make changes.
  • A BIM model will allow you to prefabricate important components ahead of time. You won’t have to adjust them based on the building design. Instead, such components are part of the initial design.
  • You can provide much more to your clients using BIM than you could with CAD. The models you give to your clients update constantly as you work on your project. Your client can check in any time, which leads to quicker approval for milestones and more efficient project development.
  • Resource tracking is a key component of BIM models. You’ll be able to figure out how much of each resource you need during the design stage. This improves the flow and efficiency of construction.



There are drawbacks to using BIM, some of which are related to the methodology’s newness:

  • Many in the architecture and engineering industries have not yet adopted BIM. As a result, you may run into problems trying to use it with some partners. As time goes on, this will become less of an issue. BIM has already grown as a concept because firms are rapidly converting to the methodology.
  • The newness of the methodology also means there is a lack of experts in BIM when compared to CAD. This becomes obvious in the extra training you must undertake to understand the model. You may find it difficult to locate suitable professionals for your BIM training.
  • You will need to spend a lot of money on new technology and software if you make the switch to BIM. While the BIM methodology will pay back its initial outlay over time, you may find the initial investment too large.


Should You Convert from CAD to BIM?


As you can see from this comparison between BIM and CAD, you need to consider several issues before you make the switch. BIM is an entirely new way of working. This means you’ll have to invest in new technology and training to make the most of it. Even if you do that, you may find you run into problems when working with people who haven’t adopted the BIM methodology.

However, by making the switch you prepare your firm for the future. BIM may not be as all-encompassing as CAD is now, but it’s heading in that direction. Like virtual reality, it is a concept that is taking root in the industry. Early adopters will have some hurdles to jump. However, doing so means they’re well-placed to be industry leaders and influencers in the future.

So that brings us back to our question. Should you convert from CAD to BIM? At the end of the day, the best choice for you depends on the needs of your firm. Smaller firms may find the initial investment excessive. However, they’ll also benefit from using a methodology that gives them a competitive edge over other firms. If you switch to BIM, you ensure your firm is prepared for the continued evolution of cloud computing technology. As others follow suit, you’ll find it easier to work within the BIM environment.

As such, you should switch to BIM if you want to make the best use of current and emerging technologies. You should also consider converting if you want to get ahead of your competitors.


Making the Switch to the BIM Methodology

Let’s assume that you have decided to convert from CAD to BIM. How do you make the switch?

There are several things that you need to do. Your choice of BIM software is crucial. Not all digital design software packages have incorporated BIM into their programming, so you need to make sure you choose one that has. The most popular of these is Revit, which you can combine with a range of rendering and virtual reality software packages to create complex 3D models.

Training is also important. BIM encompasses all aspects of your firm’s workflow, so everybody needs to undergo training. Everybody must understand what Revit or your chosen BIM software can do, otherwise, you will fail to use it to its full capacity. Some estimate that it can take as much as three months to develop your understanding of BIM. Understand this and prepare your firm accordingly.

You may also need to confront some resistance when you convert from CAD to BIM. Many of your firm’s employees will be comfortable using CAD and may not want to move away from it. The time it takes to implement BIM properly compounds the issue. Explain how BIM benefits the entire process, rather than just the creation of models. Yes, you can probably build a basic model using CAD faster than you will using BIM. However, you don’t get the benefits that speed up the rest of the process.

Finally, remember that you need to work on much of the above with your clients as well. Even if your internal team is on board with BIM, your clients may resist. Some prefer the CAD model because of its familiarity. As a result, you may need to explain what BIM has to offer to your clients as well as your team.



While there are parallels between CAD and BIM, they are two very different things. CAD deals almost exclusively with the process of designing models and floorplans. That’s an important part of BIM as well, but BIM includes so much more than your designs. BIM is a methodology that your entire firm needs to accept if you’re to stand any chance of succeeding in its use. Your firm needs to make this switch if it is to survive in the future.

Understanding what BIM does is crucial, as is finding the right software. This is where ArchiStar Academy can help. In addition to offering courses in many BIM software packages, ArchiStar Academy offers industry-best prices. For example, you could buy the Revit BIM software through ArchiStar Academy, then complete ArchiStar Academy’s BIM Revit training to learn how to use it. Contact ArchiStar Academy today to find out more.

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Posted on 20 Jan 2020

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