Avoiding the most common BIM mistakes
Articles • Central Innovation • 27 March 2018
BIM – Building Information Modelling – is an open system software suite which combines geometric and other data relating to construction components to create a digital model of a building.
While open sharing, exchanging and reuse of data is a laudable concept, it’s important to recognise that BIM – like all systems – can only work to its full potential when those inputing and sharing data are doing so in line with processes designed to minimise error and maximise efficiency.
We asked our BIM Professional Services Consultant Nando Mogollon what are the most common mistakes when using BIM and how to avoid them.
NOT HAVING A BxP (BIM EXECUTION PLAN)
Don’t make the mistake of thinking BxPs are only necessary for major projects. As with most things in life, even a less than perfect execution plan is better than none at all.
At the basic level your BIM execution plan or BxP should lay out the necessary rules of collaboration and information exchange. The rule of thumb to follow is ‘the simpler the better’ – some BxPs are overthought to the point that they are simply impractical, and end up forgotten because no one can follow them.
What your BxP needs to cover is the fundamentals – file exchanges and file types, naming conventions and the content of the files themselves. When you need additional information to be included in a particular file, that needs to be covered off in your plan specifications.
Having all expectations are set down and agreed to can save you a lot of trouble down the track. For example, knowing who is responsible for overall file coordination, which software tools are to be allowed and which technologies will be used. This is simple stuff – you can put it together in less than 10 pages.
HAVING THE WRONG HARDWARE
If you’re thinking “I don’t need the most expensive, most powerful computer” you may well be right. But what you do need is the right tool for the task – depending on the software you’re running and type of project you’re working on.
Everything from the speed of your device’s CPU to the number of cores, amount of system memory, type and size of hard drive and type of graphics card will directly affect performance and speed. Many people don’t realise that the most common graphics cards available have been configured for games and not professional CAD applications, so there’s no point buying the most expensive gaming graphics card when the one you need for your CAD work is half the price. So you don’t necessarily need the most expensive hardware but you do need the right hardware.
When it comes to CPU speed, multicores and so on, some CAD software can be more resource-hungry than others. Revit is predominantly a single threaded application meaning the majority of the time it only uses 1 CPU core, and only for a limited number of tasks will it use the remaining cores, so the most important factor for Revit is CPU clock speed. ARCHICAD on the other hand can utilise as many cores as you have available with a lot of these cases being where ArchiCAD utilises the additional cores to update all your view ports in the background with what you are doing in the open view port. While in the open view port there are still a lot of commands that are still processed in a linear way, so to have the optimum setup for ArchiCAD you need the fastest CPU core speed in addition to gaining additional time savings from additional cores. It is really only operations such as CPU based rendering, file opening, & exporting BIMx files that are truly multithreaded hence using all of the available cores to 100%. So unless you are doing a lot of CPU based rendering or exporting an enormous number of BIMx files there is no need to look for a workstation with more than 6 super-fast CPU cores. Regardless of your chosen software and workflow Central Innovation have workstations to optimise your workflow. For this reason it’s always beneficial to seek out specialist advice as to what hardware will best fit your needs. Our hardware team has over 15 years direct Architectural CAD experience and understands your software and workflow ensuring we offer the best hardware solution that will result in the maximum ROI.
IGNORING THE ‘I’ IN BIM
The I stands for Information contained in the database embedded within the BIM model. Remember your model is a replica of what will one day be a physical asset – i.e. a real building. As such, information such as costings, maintenance issues, the building plan history over an extended period, can all be included. You need to ensure the information within the model is not only correct, but not open to misinterpretation – in architect terms, if it looks like a wall in the model then it should actually represent a wall, complete with all its physical and non-physical properties including maintenance notes, history etc.
The point here is that the data embedded within your model turns it from a simple geometrical diagram into a highly valuable digital asset that customers are willing to pay for. Your BIM database can include mutilayered information – not only how many lightbulbs are needed for the building, but the life cycle of those bulbs and how much they’ll cost to replace. All this information is invaluable for the owner of the building so it’s imperative to take the time to ensure it’s accurately included.
This is a common mistake which takes two forms. Firstly, you may be working with an excessive amount of elements – like modelling right down to a level of nuts and bolts that won’t even be visible in the drawings. Secondly, you might be adding unnecessary details – such as a particular model of a fixture, say a branded tap which you might have pulled off a manufacturer’s website, when a simplified version would do. You may have chosen this because it’s readily available, not knowing it’s complex enough for fabrication or 3D printing! In such cases you will significantly increase the geometrical complexity of your model, slowing its loading speed and making it more cumbersome to navigate through. This leads us to the next two mistakes.
OVER (OR UNDER) UTILISING 3D CONTENT
Having more 3D content than you need – too many families in Revit terms, or too many embedded objects if using ArchiCAD – is just as common as not having enough, and both situations are problematic.
In the latter scenario you may end up creating essentially the same chair or table over and over, simply because you don’t have a suitable 3D model ready to be used. On the other hand, if you have too many and load them into the file you’ll end up with a project file whose libraries take up more size than the actual building model itself. If you have a building model that’s 10MB and libraries that take up 50MB, it’s akin to carrying 10 pairs of shoes around with you when you only need to wear one. It’s surprising how many projects have this problem.
OVER UTILISING EXTERNAL 2D REFERENCE CONTENT
The above principle also applies to external 2D reference content – think DWGs, PDFs, images and other common content. If you’re importing and merging such content without consideration for the consequences then you’re setting yourself up to fail. You should always check for total file size, attributes and metadata – and ask yourself is this going to conflict with my working file’s content? Better sure than sorry. It’s better to link files as opposed to merging or importing them – which can lead to file bloating and performance issues.
Bringing in a lot of external content may include data that was relevant for older software but not for the software you’re using. So it’s always advisable to audit the file first.
INADEQUATE BIM TRAINING
As with all technology, BIM software continues to evolve and it’s imperative to keep up to date. So even if you’ve been using your software for some time and are confident in your knowledge, the fact that you have developed a skillset on an earlier version won’t make you an expert on the latest version. The only way to keep up is to make sure you have the latest software and are aware of any new features or modifications.
Bear in mind that with software developing as fast as it does, if you’ve bought the latest release but you’re still using it the way you were using an earlier version 10 years ago then you’re likely missing out on much of its potential, which makes the cost of upgrading a waste of money. So as you invest in renewing your software, you should also invest in renewing your skills.
NOT RUNNING QUALITY CHECKS
In the past architects would take a set of drawings and mark them up with a red pen – this ‘best practice’ process of checking and auditing ensured that where there was room for improvement, it would be made. The principle is the same with BIM – if you check and audit your models, then you’ll identify the potential for improvement.
Overlooking quality checks will take you down the path to slow, clunky files that don’t do the job well and slow everything down. So check your models for duplication, misplaced elements, constructability (can this building really be put together the way I’m modelling it?) and standards (are your doors all a standard size that you can actually go and buy?).
Regular checking will improve not only the quality of your models but the final quality and consistency of your drawings, and the eventual constructability of the building.
FORGETTING ABOUT DELIVERABLES
You’re working on a project, you have a good strong BxP, the right hardware and software, and everyone knows what they’re doing. Sounds great – but don’t make the mistake of concentrating so much on the modelling that your typical contractual deliverables – i.e. drawings – start falling behind your own standards. In other words, don’t let the effort you’re putting into BIM workflows get in the way of your desired outcome.
It’s unfortunately common to see this with some younger companies who are trying to take the leap to become fully BIM implemented. The right approach is to take control over the models with the aim of automating and improving the quality of your drawing deliverables – that is where the most basic value of using BIM lies.
That way, not only will your drawings be easier to produce (via automation) and more consistent – you’ll also increase the type and quality of your deliverables, by producing digital assets for your client to take over and work with.