Sunday, November 2, 2014


First of all, a big thank you to Zach for some very kind words, for running his inimitable competition and for motivating me to get carried away again.

I intended to clean up my Desert Pumpkin families for upload during the course of last week, BUT work just got too hectic.  Towards the end of the week I got wrapped up in an exercise which I thought worth sharing.

It's a design and build project for a hotel with prefabricated bathroom pods.  The exercise involved enlarging the pods while maintaining the minimum area requirement for the guest rooms, which happens to be 24 sq m.  There are several different permutations of pod type and bedroom type.

We had to come up with a drawing that explains our proposal in order to achieve client sign-off before committing changes to the model.  A classic case for 2d BIM, which is my nickname for "drafting over model views" It would be possible to make a second copy of the model and implement changes in 3d.  But it seemed to me this would require more effort, and it would be difficult to show existing and proposed as overlays in the same view.

We are familiar with the concept of 2d BIM as a detailing technique, but I believe that it has many other analagous uses, and as such it is a method that deserves much more attention and respect.  It is particularly useful in a situation where you are exploring planning options, where it is directly analagous to laying sheets of tracing paper over hardcopies and sketching as you talk during a design workshop.

So I created a parametric detail item with 3 types, representing the 3 main pod types. There are a number of dimension strings that lock various fixed relationships in place, plus 3 variable parameters (also one visibility control).

Overlay this on a plan callout and dimension it up.  I'm using two colours of dimension for existing and proposed.  The resulting diagram is quite busy, but for team members who know these pods inside out by now, it's immensely informative.  Also you can go on generating variations until the cows come home, either by duplicating views with detailing, or by simply swapping out family types and printing off the sheet.

These same detail items are placed in a key plan, and used as guides for the edges of filled regions, one for each of the permutations of guest room/pod (we have six at present)  The edges of the filled region are stretched to align with the outer edges of the detail item and give a readout of the resultant area.  Unfortunately we can't tag the area of a filled region (seems like an unnecessary limitation) but it's no biggie.

So we have a key plan which summarises all the different situations and together with the various callouts for the pod types tells a very rich story.  Furthermore, the 2d world represented by this sheet is a very productive design space.  It's a great place in which to work while grappling with the problem at hand.  2d BIM is a very powerful tool for thinking out problems, analysing and abstracting, defining the critical issues, staying fluid and flexible.  We should use it more often.

So there you go: a nice, short, practical post to contrast against the epics of the past few weeks.  Call me schyzo if you like, but I enjoy using Revit to range all the way from drafting techniques to the conundrum that we call art.  That's why I call it my BIM pencil.

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