Chapter 6: BIM for Contractors

The chapter discusses ways BIM can help contractors.  The chapter often mentions learning curves associated with new software and the need for early integration and collaboration; but with every topic discussed, it gets related back to being able to save the contractor time and money.

After reading this chapter, I realized why BIM has only recently caught on as a standard for construction management firms: there is a steep monetary investment.  There is a few pages dedicated to estimating and takeoffs, which cannot entirely be done in BIM.  To preform estimating, additional software or plugins are needed and a detailed model will be required. Learning curves associated with new software is an additional investment to firms.  According to the chapter, 91.6% of firms are made up of less than 20 people.  To purchase licenses to all the necessary software, getting their employees trained/hiring new employees who know the software, and making sure their computers are capable of running the software are all items a small firm will have to be able to budget for before committing to changing the way the have been operating.

Figure 1. Data collected from more than 750,000 firms collected from the US Census Bureau, NAICS 23-construction.

The chapter makes it very apparent why contractors should be using BIM, and the one I found to be the most interesting (as did Teddy Bruder) was the clash-detection abilities.  Clash-detection software is a much safer bet when it comes to potential interference with systems (whether that be other systems or building components), which can save a lot of time and money for all parties involved.  The standard way to tell if a system was ‘clashing’ was to gather all of the subcontractors’ drawings on a light table have a person try and determine if there are any overlays.  This opens up a lot of human error that will not be seen until the systems are installed - costing everyone money to reinstall/rework the systems to all fit.

Another section I found very interesting was the impact a 4D model has for the coordination and budgeting of a project.  A 4D model includes a time parameter that can highlight any shortcomings in the design that will conflict with other trades not starting on time.  Easton often states that this work needs to be done by the contractor, which will then be a great benefit to the architect and owner.  Again, relating back to how the contractor can save time and money through the use of a computer model vs hand drawn models.

Reference:

Chuck Eastman, Paul Teicholz, Rafael Sacks, Kathleen Liston; “Bim Hanbook, a Guide to Building Information Modeling for Owners, Managers, Designers, Engineers, and Contractors” Second Edition, Chapter 5; Second Edition 2011

Commented On:

Michael Kilgallon:
I've never heard of Tekla before: I'm going to guess that BIM was intended to originally help for coordination of the interior systems, which are pretty independent on the structure. Then again, I just read about how BIM helps contractors (chp. 6), so coordination of subcontractors is on my mind.

It's interesting that you pointed out that each program fits a purpose. Chapter 6 mentioned the constant need for additional software to do things such as estimating. Luckily, since AutoCAD has many of the additional program needed, using Revit would accept those plugins. Not sure how any of the other programs interface with additional software that may be needed.


Audrey Ryan 
It seems like so many aspects of the construction industry lags behind the available technology. I think it has a lot to do with the monetary investments needed on behalf of all parties. While a large architecture firm can make the investment into BIM, smaller subcontractors will still not be able to make that investment. Otherwise, I couldn't see how the old light-table checking for overlaps would have lasted as long as it has.

You brought up an interesting point about designers needing to trust the models. It are me think how many people will be working on this model: if the wrong one is chosen, the whole project struggles. Then instead of saving time and money, it ends up causing frustrations or blips during construction.

Brian Benson
I didn't realize that IPD was a result of Designers trying to pass the blame. I think it is a great incentive for designers to design buildings holistically (as we learned about in AE390/391) by being responsible for the project until its completion.  I feel, in general, that BIM has aided in the construction industry working together instead of as separate units; so it does not just benefit the systems within the building, but the industry itself.