Friday, September 15, 2017

My Kingdom for a Dimension...or Two...Three

A Friday thought...

I've spent the last couple years doing a lot more modelling work than I expected to do. If you asked me in years before I'd have told you 80-90% percent of my time was dedicated to training and implementation activities.

Much of the modelling I do these days is from the contractor's point of view, for them. I quite enjoy it. I learn a lot and it keeps me on my toes.

This work is requested often because the documents they are using are not created from models to begin with. Sometimes they are but they (the contractor) have to build based on drawings so they find it informative to attempt to build things in the computer before doing it in the field. Where have I heard that notion before?

Chief among the things that trouble me doing so is the lack of dimensions. If there are lots of dimensions then the issue is their message or rather the lack of clear intent.

All too often I find a slab edge plan is lacking that one dimension, between adjacent slabs for example, that I could really use. In other instances the decision to start plotting the dimensions is based on a datum that involves a fussy site related angle (like based on a property line); when other orthogonal options are available.

I've also seen far more effort and devotion applied to dimensions for parking stripes in a parking garage than for the structural elements that make it possible to paint those stripes eventually. Then you have the dimension value bust. Such as, setting out the building grids reveals a subtle mathematical inconsistency or outright typographical error or override.

Then there are the dimensions that describe how to place something relative to other elements that get installed later during construction. How do we place a concrete column by referencing interior partitions...when those dimensions don't relate back to grids or structural elements? That issue is both missing dimensions and logical progression.

Often I have to endure the game of look over there, as if a hockey puck is getting smacked back and forth, when one says look at those guy's drawing for more information and then the other says the reverse. Slab edges that are required to overlap (per nearly matching details) are a real chore to sort out when you have to flip back and forth constantly and double check against the reflected ceiling plans...oops they're inconsistent with the plans...note to generate an email...

Then there are arcs. Thanks for all the radius and diameter information. Could I get dimensions for their endpoint locations and chord height/width? Better still, could I get something that tells me where their origins are supposed to be? Yes I do realize that one or two might be located somewhere on the outskirts of town. Then again if doing so exposes that issue up front when they are sketched, maybe we could get some other localized notion of how to place them on site too?

Though I've rarely encountered it in real life, I've really learned to appreciate the my documents stand on their own philosophy. In other words, a structural set of documents could be used in isolation to build all the the structural elements required, correctly, even if the rest of the work never got funded. It IS harder to do because it requires concerted effort to coordinate the disciplines well.

Yes I know, it's complicated, building stuff is messy. Now that I mention it, have you noticed, like me, that those ugly fractions people don't like seeing on drawings still crop up everywhere in real life.

Ah well, enough complaining. I've got some slab edges to reconcile. Back to grumbling to myself again. May we all enjoy a dimensionally accurate weekend!


Andy Milburn said...

Hi Steve

I enjoyed this post. Rang a lot of bells for me, things that concerned my when I used to lay out drawings using pencil and paper. What dimensions does the builder really need? How can I make this drawing easier to read? What is the purpose of this particular view?

One of the reasons I have continued to be an architect working on live projects rather than a full time BIM specialist is the need to stay in touch with those kinds of issues.

Anyway, I miss you buddy, hope our paths will cross again before too long.


Steve said...

Thanks Andy, me too!

Leslie Smith said...

Thanks Steve,
As always I enjoy your expressions!
So true...I am working with a new montra is..."how are they gonna build it if you don't tell them...(fill in the blank). Dimensioning fits right to the discussion.
I think for those of us from the way back drafting-on-the-board days, we grew organically. After all you needed to actually look at a scale as you worked.
But for the newbie's with lots of computer playtime...I've noticed a bit of a disconnect from thinking things through start to finish. It's so much more fun just to build a model.

AnthonyB said...

Great post. Thank you for sharing. There will always be issues of what Revit can do quickly versus what you should do; getting team-mates to think about the consequences of their actions: for the documentation, the model, and for the physical building; constructability and timing; single place or multiple documentation annotations. I look forward to the day we can issue the model, period.

mgonzalez said...

Hi Steve,

While I understand your frustration (I've modeled many an existing structure myself), the "my documents stand on their own" philosophy is simply not real life. At least, not in my experience in the structural discipline. I would simply NEVER dimension something that is the architects responsibility to lay out unless the dimension is structurally necessary. Legally speaking, a dimension on the structural docs overrides anything on the architectural set so every dimension I snap gets me more liability. Obviously, a certain amount of that liability I signed up for and will gladly accept but there is typically no sense in taking on more than I signed up for. Also, where I currently work each discipline has a horrible habit of designing in isolation. Forcing them to look to other disciplines for what they were each meant to provide in the first place has been a very good thing.

Don't get me wrong, I have encountered the problems you mentioned (disagreeing details, overridden dims, dims to illogical things) so I feel your pain. But at a minimum someone should need the arch and struct set in order to model (or build) a building, even just to get the structural elements in place.