BIM Estimating: Myth vs. Reality


There are a couple misperceptions in the AEC community about what is and isn’t possible when combining BIM models with the Estimator’s standard workflow.  Take this quick True or False quiz to see if you or your organization has fallen prey to one of the myths.


True or False:   In order to do a BIM-based estimate, every element of the building needs to be modeled.

True or False:   In order to do a BIM-based estimate, the Estimator needs to learn how to model.

True or False:   In a BIM-based estimate, as long as you know what buttons to press, the system will spit out an estimate.

True or False:   Since BIM models are always perfect, there is no need   to check the quantity counts for use in construction calculations.

True or False:   A savvy BIM Manager can replace a Senior Estimator if he or she has the right software.

True or False:   If you haven’t seen BIM mandated in a contract, there’s no need to future-proof your firm.


So, do you think you can tell myth from reality?  Now let me tell you a true story…


In my role here at Trimble, I get to meet with great people who are leading the BIM Initiative at their firm.  Inevitably, these folks are enthusiastic about technology and really like to dig in and thoroughly understand a topic.  This is a delight to me because I can share my “Well, back when I was an estimator, we used to…” stories and mentor these leaders as they work to bring BIM concepts and workflows to their organization.


I had been working with one of my clients.  He wanted me to “look over his shoulder” as he organized a full structural estimate.  What made this unique was that this gentleman was not a regular estimator, but rather the company’s “BIM Expert.”


He had published the models and tied them to his company’s concrete database.  Then he made great use of location-based quantities in the estimate and everything was good.


The actual Estimator on the project had to turn around a price in two days and, wanting to stay focused, preferred to stay in his comfort zone with 2D takeoff.  He was going to need to invest the full forty-eight hours in the estimate, but he knew it would be complete, cover all scope, and feel good about it.


The BIM Expert asked, “Why are you doing that?  I’ve already published the models and tied them to our concrete database.  I would really appreciate your insight, though, as I’ll never have as much estimating expertise and experience as you.”


The Estimator replied that he really didn’t have any spare time with the deadline looming and really needed to concentrate on the task at hand.


The Head of Preconstruction overheard the conversation and asked if the Estimator could spare twenty minutes to investigate the project estimate in Vico Office…and if the BIM Expert could highlight the areas where he really needed some experience.  After all, even he didn’t trust that there was a full takeoff and pricing completed in a couple hours!


The three of them went to a small conference room and projected onto the screen. 


As it turns out, there were some differences between the 2D drawings and the 3D model.  For example, one issue that popped out was $40K of missing formwork for some columns.  The item was miscalculated using the 2D process. The item was missing from the 2D drawings but luckily, it was picked up by 3D takeoff in Vico Office.


Now I know from experience that you will inevitably have ups and downs in your estimate and luckily it often seems to balance out overall.  But unfortunately that is not always the case and obviously you can end up losing money or losing the job if you have overpriced.


Finding $40K of missing formwork might not sound like a big number in the grand scheme of things, but you could buy a lot of virtual construction software with that and eliminate these issues!  There’s your return on investment: ten seats of Vico Office for just the price of identifying one mistake.


As the group was going through the estimate, they identified 3,500 cubic yards of concrete that were overpriced. That’s about $700K and an easy way to lose the project.


These two issues equated to $660K which can be a nice to have depending on the contract type, but a potential killer if you’re in a competitive bid scenario.


Having the highly-visual integrated connection between 3D, takeoff, and estimate is a massive benefit, and I think a stress reliever knowing that when you go into your bid review meeting  you can have the confidence that your base estimate is correct.



Caption: Beyond the three people working on the estimate in the conference room, Owners also appreciate this three-way view of the project: the 3D model, the cost plan, and a color-coded tree structure which indicates the building systems which are within budget, outside of budget, or missing information. With one click, the Estimator can show the Owner the specific piece of the budget in both the 3D model and then explore the line items which make up the cost assembly. No three-ring binders of spreadsheets, no rifling through drawings, no searching for assumptions – just one screen of highly-visual data.


So, which of these myths at the top of this article are true?  And which of these myths are false?  If you’re still not certain, just watch this thirty minute video: BIM for Estimators.


And here’s a plug for my colleagues who have written blogs or produced webinars to dispel these myths:

Blog: Why Trimble Offers 3 Construction Estimating Solutions

Blog: When Estimators Block BIM

Blog: Does BIM Mean Estimators Are out of a Job?

Blog: There Is No Easy Button for Quantity Takeoff

Webinar: An Introduction to Model-Based Estimating

Tags: bim-based estimating, quantity takeoff, construction estimate, bim myths, bim expert, bim manager, construction budget, cost plan, 5D BIM, bim estimating, bim true or false