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Why is BIM important to CAD designers? Will BIM replace CAD?

By Charles Thomson
January 22, 2019
This article is the CAD designers crash course on BIM, it will explain what it means for design and how it is creating opportunities to test new ideas and improve outcomes while reducing costs.

Computer-aided design (CAD) has played a pivotal role in manufacturing and construction for decades. A generation of designers have grown up knowing no other way to get the job done. In recent years, however, ‘BIM’ (Building Information Modelling) has arrived, particularly in construction, as the replacement for all things CAD — causing understandable consternation among professionals who have built their careers using CAD tools and techniques.

Although BIM is changing design, taking advantage of these opportunities is probably less disruptive than many CAD designers believe, while simultaneously being more meaningful. This is the CAD designers crash course on BIM — what it means for design and how it is creating opportunities to test new ideas and improve outcomes while reducing costs.   

Is BIM actually distinct from CAD?

The answer to this question is harder to pin down that it first seems. BIM is a lot of things to different people, becoming as much a marketing term as it is a means of describing something unique and different within design and technology. In some cases, BIM is simply a new term used to describe CAD software. Even at its most distinct, BIM mostly describes a set of processes that allow for the more effective application of particular types of CAD software. Either way, BIM and CAD are, at the very least, interrelated. But, to really get to the bottom of this, we need to back up and explain some of these terms in detail.

Levels of BIM and the BIM mandate

In April 2016, a BIM mandate came into force in the UK for all publicly funded construction projects. This created the regulatory terms BIM Level 0-3 that together provide a great overview of the many definitions of BIM and how CAD sits within it.

BIM Level 0 simply describes any CAD, while BIM Level 1 is used to describe object-oriented CADs. BIM Level 2 (which is the ‘level’ of BIM necessary to meet the UK BIM mandate) also describes CADs. However, to meet the BIM Level 2 requirements, those CADs need to be able to export to one of several common file formats, such as IFC (Industry Foundation Class) or COBie (Construction Operations Building Information Exchange). BIM Level 2 projects also need to create and maintain a collaborative data environment (CDE).

The still undefined category of BIM Level 3 is where things start to get a little bit different. BIM Level 3 includes what many BIM enthusiasts claim to be true BIM — database-first design that creates a single-source-of-truth for all design inputs. Rather than developing designs using separate programs and creating separate files for every different format needed throughout construction and planning, BIM consolidated that all into one dataset that is accessed by each member of the team.

This connects the design programs used by all members of the team into a single interconnected dataset. The actual programs (or at least formats) do not change. Simply, the specific CAD software choices are limited to those that are compatible with this new method of data storage. But, updating to this type of process is not fundamentally different from changing the software you use for another reason.

What database-first BIM delivers that is so important to CAD designers

What ‘true’ BIM delivers, making it worth migrating to software capable of database-first storage, is communication and efficiency. Rather than creating an administrative nightmare every time a new set of software is used to access structural or design data, everything is kept together. This improves the ability of teams to work collaboratively while decreasing the chance of creating errors or clashes within designs.

This makes it easy for CAD designers, architects, structural engineers, interior designers (and even the client) to work closely together throughout the design process. Rather than tackling the project in phases, it becomes easy to receive cross-disciplinary input throughout every stage. This allows architects to push the limits of structural possibilities, while CAD designers are not forced to redraft whole sections when engineers come back claiming that the designs are not structurally sound. Once the project is close to complete, it takes less time to acquire clash detection reports and less time needs to be spent cross-checking every element of design.  

It also makes it simple for CAD designers to deploy multiple drafting tools simultaneously and interchangeably without having to worry about updating multiple files. This can even include the use of 3D models as the project develops. Effectively, BIM delivers to CAD designers what it delivers to the entire construction and design process — flexibility, accountability and control.  

BIM’s big effect is on the construction process as a whole 

To really understand what BIM offers design and construction, however, you need to look at the process as a whole. CAD designers only play one part. BIM is about communication and information availability. This impacts the job and day-to-day of every individual involved. But, its cumulative effect changes the possible outcomes — impacting the design and steps taken along the way.

One big impact is in the use of prefabricated materials. The project information and detailed scheduling data makes it easier to reliably depend on prefabricated structural components from both a quality assurance and logistical standpoint. This creates huge efficiency and cost savings to the entire project, and impacts drafting considerations throughout the design process.

This is being further augmented by the application of laser scanning technology and LiDAR techniques to create point cloud surveys of building sites and prefabricated materials. This is one element of what is know as scan-to-BIM. Through the application of this technology and techniques, complete quality control can be guaranteed, and it is even accelerating the adoption of experimental manufacturing techniques such as 3D printing.    

Summary: CAD designers depend on partnerships to make BIM important

The fact that BIM is all about communication means that its impact is directly tied to its application within the wider environment. If a CAD designer has BIM enabled software, but is operating within a design team limited by traditional workflows, nothing fundamental will change.

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BIM is a process as much as it is a technology. For that collaborative process to be possible, everyone within the team needs to be enabled by BIM technology. What makes BIM different from traditional CAD is the collaborative capabilities it offers to its users. Otherwise, it is simply computer-aided design — and, as we have discussed, sometimes what is called BIM is simple CAD.

For CAD designers looking to benefit from BIM, the most important thing is to make sure that the teams in which they work embrace the new technology and processes. That means going past the BIM Level 2 mandate to access truly database-first, single-source-of truth software that opens the door to the experimental possibilities delivered by improved communication.

The same goes for developmental aspects of BIM including scan-to-BIM cross-checks. Like with BIM, not all point cloud workflows are the same. Advances in things such as multistage, vector-based processing software for targetless registration is enabling some survey teams to operate more efficiently than others. Accessing these types of partners further expands the possibilities for the application of this technology within a BIM framework. For example, construction sites can be scanned prior to planning and models built on top of that data. Access to this type of informed starting place might have some of the largest direct impacts on the daily tasks of CAD designers and is directly tied to working with survey teams enabled by the cutting-edge of their own field.

The true heart of BIM, however, is collaboration. Where BIM is applied beyond marketing jargon, it is a process to improve the use of CAD enabled by a new way of looking at data storage. BIM and CAD are not fundamentally different, BIM is a new way of developing collaborative workflows within a CAD enabled environment. When done appropriately, this move delivers truly transformational outcomes. But, to achieve this, CAD designers have to find partners who are as invested in technologically enabled processes are they are.

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