This post started off as a response to a comment on a previous one, then, coincidentally I had to deal with a ‘what LOD and when to specify – why remodel the same thing over and over – who is doing what – what is the point of it – etc’ type of (very typical) BIM question somewhere else and decided to give another go to bring the ‘fairy tale BIM’ sphere closer to the real world of design, procurement, construction and post construction O&M.
And to do this using a description of the lifecycle of a (fairly) typical construction detail.
Now, anyone with 2 feet on the ground of the real construction world will say, that everything written (and illustrated here) is no rocket science, but common practice.
Yet, a lot of these well-grounded gentlemen (and a few ladies) will make the ‘leap of faith’ when they get sprinkled with the golden dust of the BIM fairy and expect/believe that, the same lifecycle will not happen once linked to the magical BIM box, or if it does, they will have little to do with needing to aid the creature through its development stages, since this BIM will make it all ‘automated’.
Admittedly, my main and real reason for writing this post, is to float (again) the belief that buildings are ‘A set of 3D grids and critical points‘, that define it and the management of those will make the info management of the building succeed or fail, no matter if the approach is fully manual, pure 2D CAD, a forced conglomerate of 2D/3D or a sleek real BIM (of as many Ds you like).
That sentence I just wrote, is a mouthful, but do read it again.
Trust me, zillions of dollars (and other currencies) and just as many man hours are flushed down the loo daily all over the word, because of those involved in the process do not understand this little ‘secret’.
In the past, I tried to use all sorts of parallels to explain this idea, from the ideas of visual skeletons, to coatracks fixed in space, but I still find myself meeting blank stares when I try sharing this as the ‘BIG secret’.
So, today, I will make another attempt to describe the concept of the ‘internal grid’ of a building (any building) through the lifecycle of ‘a detail’ (any detail).
First, a little bit more musing on ‘grids and points’. Grids within buildings are not new and have been used for centuries. Those are the setout lines that drive the way building elements are spaced and relate to each other. These grids are 2D and represented (mostly) in plans. They are then, complemented in the space with the 3rd dimension (that are usually represented by stories and levels). So, with the help of these references, in theory at least, anything within a building could be located exactly within the space.
For a successful project, these references get fixed as soon as it is possible, and are not moved. Ever.
Of course, one must stop here for a moment and note, that in the current world of squashed-up design timeframes, speculative developments and general fluidity of (not just) the design but the brief and even the fundamental end-use of most construction projects, this goal of a permanent virtual skeletong it is often an almost impossible thing to achieve.
Designs evolve, grids get moved, storey levels get changed – entire floors added or deleted etc., in spite of all of that, critical efforts must be made, that the internal grid (skeleton, coatrack) is maintained and controlled. Because, if it is, the rest is sooooooo much easier.
And I mean, everything, getting IFC drawings, as-builts, shop-drawings, or magical, know it all 3-7D (+) models.
So, imagine a detail. Any detail, really, scooped out of a finished building.
Now, think of it as the cliché butterfly from the ‘caterpillar-to-butterfly’ story of your biology classes of the past.
This detail of yours will (must) evolve in a similar way, but with many more stages involved, and a ‘hell-of-a-lot’ more human intervention and a ‘hell-of-a-less’ predictability than its natural parallel.
But, it is still a pretty good example of how any part of a building must to go through its development, no matter what approach you choose, from a traditional Design-Tender-Construct, fast track to D&B.
You can bring in the ‘magic painters’ that will paint the dots on the butterfly early in, but with little use, if your caterpillar is still merrily chewing on the green leaves.
You could try though, to hasten the process by having the ‘dot painting magical painters’ being in the right place when the right time arrives, by say fixing the caterpillar to a certain place so there is no time wasted in chasing it, at the correct time.
I know, this sounds loopy, even to me.
Let’s try again.
Think of a precast wall. Someone (likely an architect) will set out, that ‘a wall’ will be a precast type.
That wall will then (possibly by a structural engineer) chopped into pieces and the sizes determined. Then, likely the pieces will be designed by a specialist subcontractor, who will prepare connection shop drawings for someone to approve.
Before that happens (or in parallel), a main contractor will likely prepare shop-drawings linked to those precast elements piles, connecting slabs, roofs etc. Hundreds of people will be involved in creating drawings, models, drawings-and-models describing this particular wall from the time it was only 2 lines drawn by an expensive pen through (maybe) a smart, but still linear 3D+ wall element, through lines again as a set of plans and elevations to (maybe) a smart prefab model for the specialist subcontractor.
People that devise sophisticated BIM workflows spend a lot of time, trying to line up the above participants and force them to use one, or at least a small number of fully-integrated and compatible models. They go into significant efforts to use and reuse models and not ‘waste them’.
Yet a properly used and discarded model part, like the chrysalis’s shell is totally acceptable collateral ‘damage’. It is the retaining of the critical spatial position of various elements and their critical relationships that will truly guide a wastage of time and efforts.
Aiming for a fluid BIM approach I still see as an honorable goal, but is unlikely to work without, (you guessed) the proper management of the virtual building skeleton (the grids and points).
So, if you want a good BIM manager, you may ask at the interview from the proposed candidate, ‘How he/she maintains the health of her building skeletons?’ (you will need to know what answer to expect too, but I leave that for another time).
As a read through this post, I feel it disjointed and all over the place – so, I do try to pull together a meaningful end. I also look for a good illustration of the point I wish to project here.
Believe it or not, I have practiced this mantra of the ‘sacred skeleton’ I am preaching here for you over at least 2 decades and on hundreds of buildings and have many good examples.
In my search I found a little 3D PDF file that I will share with whoever would like to look at (email firstname.lastname@example.org) it. You can use LinkedIn messaging to ask for it too.
I hope Naylor Love will not mind me sharing the file, but take the gesture as my nod of compliments to their visionary director Scott Watson, who some time ago walked for a while with us on our journey to reshape the world of construction.
So, rather than giving you a meaningful ending, apart from the message that I sprinkled through the post ad nauseam, I am sharing you an example of a 3D PDF – that was made a good 10 years ago (this is just a ‘make believe one,’ but we made many of real and important buildings too) – an approach and technology I am yet to see anywhere else – even close to it.
Make sure you enable the 3D features of the pdf and remember, it is a PDF.