How much should I model in ArchiCAD? (Part 2)
Don’t make something unless it is both necessary and useful; but if it is both necessary and useful, don’t hesitate to make it beautiful.
In yesterday’s post, I started looking at the question of “How much should I model in ArchiCAD?” If you haven’t read that yet, start there. Let’s continue with that discussion, but this time focusing on “What Should I Model” and “What Should I not Model?” And again, these lists aren’t exhaustive, but are meant to get us all thinking about the complexity of this fundamental question.
What Should I Model?
- An old rule of thumb from gurus on the forum is this: When deciding what to model, don’t base that decision on size, complexity, or drawing scale but on how many times you see the element in question. The more times it is seen, the higher the probability it should be modeled. In general if some element is shown two or more times, model it. If it is once or zero, it’s debatable (more on that later). Remember, when doing this analysis of whether to model an element based on number of times seen, an element might show up in a plan, section, elevation, 3D view, interior elevation, schedule, detail, etc.
- The answer to this question varies by project type. Baseboard is a great example. For high end custom residential, I always model it. For some other project types, say hospitals or airports, I might not. You might be thinking, isn’t that bad BIM? Doesn’t the hospital or airport contractor need that information just as much as the custom residential team? Of course. Or maybe more so. But in a project with hundreds of rooms, is there some other way that information can be documented? For instance, instead of modeling all the baseboard, could Zone Perimeter be used as a good proxy? Perhaps. The point here isn’t to find the right answer, but to remember that data doesn’t have to also mean 3D representation. Often we can just add text based data to less complex model elements to convey as much or more (this is one of the reasons I am so interested in IFC properties these days).
- The answer to this question varies by output type. What are you producing in the end? Traditional documentation? Something more advanced? A few schedules? Tons of schedules? A BIMx model? Is there one piece of documentation that is the driving factor? If your primary point of communication with your client is a BIMx Docs model, then model for that first. If your goal is quantity take-offs make sure you model in a way that supports that, even if it means less glamorous 3D views or “uglier” 2D views (not that either of those are a given). Depending on your primary output, visual 3D perfection might not be the goal.
- The answer to this question varies by collaboration requirements. Are you exchanging IFC with your engineers or other team members? Are you just doing DWGS, PDFS, or smoke signals? Depending on what information you are sharing with others, and in what format, you might decide you need to model more or less. For instance if you are working with a structural firm that will be modeling their work, then you shouldn’t be modeling any of that. Of course if you are going down that path, you’ll need to spend time COMMUNICATING those decisions and making sure the data exchange works. Here’s some advice for that.
What Should I not Model?
- Just because you can, doesn’t mean you should. Or need to. Will not modeling something make your life easier? Stefan Boeykens wrote a post a few years back entitled Improve usage of BIM during early design phases. All his advice is great (and pertinent to this topic), but it’s his sixth point that I want to highlight: “Model as little as possible…” What if we turn things around and look at the “How Much I Should Model” question from the reverse. “How Little Can I Model?” When trying to decide what to model, assume nothing should be modeled and find proper justification FOR modeling. Some things are easy (Walls, Windows, and Doors in every project of every scale). But as we dig deeper, the answer clearly becomes more complex.
- If 3D is slower, unnecessary, or harder to manage, don’t model it. There are things in much of my typical work that aren’t shown more than once. Most electrical, some structural, and a lot of site plan info, for instance. In those cases I do whatever is fastest—sometimes using a tool that results in 3D data is faster, sometimes it’s slower. But while I say this, I also know my work is going through a transition. I used to use 2D lines and groups of elements to show most of my electrical info. Now, even if I’m turning off the 3D model, I try to use Objects that have a 3D component for all my switches, outlets, and light fixtures. I am preparing to show this information. Or at least to be able to turn it on if I need it. Or if I’m not using 3D elements, I’m drafting everything with Fills because Fills can have IDs and can be scheduled. That is a forthcoming post. This technique allows me to ignore the 3D geometry but still get the benefits of model once, show multiple times (in this case showing a light fixture in both plan and schedule). The important point here is 3D isn’t always better. It usually is, but it isn’t always true.
- When you have run out of time, money, or knowledge. There are instances where you can model up to a point, but then need to leave a void. Two years ago I was working on a townhouse in the outskirts of Houston. I’ve shown the model before (here and here and here and elsewhere). It’s a hyper detailed model. We modeled things I’d never recommend modeling (when a client is also an architect and a friend, this sort of thing happens). When it came to deal with the curving, grand staircase, I hit the edge of both my ability and the capabilities of ArchiCAD 16. I started modeling the stair and it was awesome. But then I hit glitches and it was going slow because I didn’t know the Morph Tool well. And I was finding aspects of the design that I just wasn’t sure about. So I stopped modeling. I built the treads out of slabs because that was easy (and valuable) and just faked the rest. Some images are below. The rest of the section is all modeled (except for the framing, which was easy to do with the 2D Lumber Object). But that stair is a huge lie. It doesn’t matter. Our drawings weren’t going to be the basis for the construction of that stair anyways. It was going to be built in situ by experienced craftsmen who had done many stairs like it before. We’d modeled the rest of the building well enough and did the math on the stair to know it’d work fine. So I just faked the drawings and moved on with my life. It sadly meant the 3D model couldn’t be used for walk-throughs without explaining the incomplete stair, but that wasn’t the end of the world. And to be honest, drafting that stair felt so good. It reminded me of happy moments as a young intern, in my early ArchiCAD (and pre-ArchiCAD days), when creating a stair section meant making a half-lie thing of beauty out of lines where not really knowing (or needing to know) the ramifications of every single one of my actions was okay.
- When no one cares. Let’s be honest. Sometimes the only person who wants to see something modeled is the person sitting in front of ArchiCAD. Sometimes the reason we want to model a certain thing (or add a piece of extra data) is because it’d be fun or a good challenge. But that’s no always valuable to the client, the project, or the budget. It’s up to us to remember to ask the painful question of “am I fussing over this little bit of model for my own pleasure?” If the answer is yes, think about the benefits of not modeling.
I feel like these two posts covered a lot of this topic, but there’s still so much more. What do you think? What did I miss? How do you decide what to model or what not to model? What examples do you have from your own experience with this question?
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