I AM [actually] AN ARCHITECT

Errors and omissions in construction documents are expensive.  Everybody involved in the building industry benefits when there are fewer E&O’s.  Building Information Modeling (BIM) makes it easier to reduce E&O’s for several reasons.  Among them:

• Modeling the building in 3-d forces us to see clashes and strange conditions that we often miss when drawing in 2-d

• The information is coordinated between views.  It is impossible to do things like accidentally draw a door differently on the interior elevation from one side of the wall than on the other side.  It is also impossible to draw one type of door but accidentally enter a different type into the opening schedule.  This is because you model one door, and that same information is then automatically entered into the spreadsheet and viewable from any angle or sheet view.

So it would seem a no-brainer that we architects and engineers should be using BIM to make out documents tighter.  But what if you could make your documents too tight?

We are facing a reincarnation of the problem that first arose when our profession starting using CAD.  With CAD, you can zoom in and draw things accurate to the 1/32”.  But people can’t build within 1/32”accuracy.  So if you design beautiful little jewel boxes that only work if everything is as perfectly coordinated as your computer-aided detail, it is bound to fail.

A recent article in Engineering News-Record (ENR) talks about the first known claim related to an architect using BIM.  The architects and engineers tried to tackle one of the biggest problems with complex buildings: above-ceiling coordination.  

Even with CAD, our profession has continued to draw the mechanical, electrical, and plumbing systems diagrammatically.  Then, during construction, we let the contractor try to figure out how to make it all fit up there.  When they insist they can’t make it work then we step back in and do things like thicken walls and re-route ducts.  It’s a messy, inefficient process.  It’s a grey area that involves finger-pointing.  Is the design unbuildable, or is the contractor just being lazy and unimaginative?

So this team (on an un-named project) tried to cut out that maddening process by modeling the whole mechanical/electrical/plumbing system in real sizes in their BIM.  The problem is, they did it entirely without the contractors’ input.

They designed the system that goes above the ceiling to such tight tolerances that it became very difficult to build.  Had they been doing this along-side the builders, they would have been able discuss how much room a man needs to get his hand in to turn screws, and how accurately they can place things.

When bidding the documents, they did not place a note or special bulletin alerting the builders to the fact that the MEP systems were designed to a tighter tolerance than industry standards.  Even after the contract was awarded, they did not discuss this departure from industry norms with the building team.

It was not until the building team was 70% through assembly that they realized they couldn’t execute what the design team had envisioned.  What do you think came next?  A lawsuit.

It’s a great idea to try to make our documents more accurate and complete; but the purpose of such efforts should be to verify that our designs are buildable.  Buildings are simply too complex to think we architects and engineers can decide what is and what is not buildable without discussing some keys things with the builders who will execute the designs.

Now that we are in an age of BIM, it is increasingly clear that designing without the builders at hand is just dangerous.  I, for one, will not be practicing architecture under a design-bid-build structure again.