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BIM for Bidding

Let’s face it: Quantity takeoff is time-consuming. It is the single most labor-intensive portion of the bidding process for trade contractors. No matter how proficient you become with a computer, every wall and ceiling estimator spends hundreds of hours every year performing quantity takeoff.

Now, you may say that this expenditure of time is unavoidable. Wall and ceiling contractors need detailed, accurate scopes of work in order to bid on (and eventually build) jobs. However, most of the hours that estimators spend performing quantity takeoffs are not as productive as they could be. Why? Because experienced estimators can spend a limited amount of time with project documents and acquire a working understanding of them. The balance of the hours spent painstakingly dragging lines over walls and ceilings—time not essential for understanding a project, but only necessary to create a detailed and accurate scope—is lost time.

So what if drawings were to arrive at your office with much of your scope already written up? What if drawings were intelligent so that many of the quantities you need could be generated automatically? How many more jobs could you bid on? How many more bids could you win? What would that do for your annual volume and, ultimately, for your bottom line?

A Possible Solution

Building Information Modeling has been discussed for a while now. I have been investigating BIM for the last three years, and many other contractors have been involved for much longer than that. But as I have sat through talks and read articles, one question has been on my mind: How does this new technology help me bid on jobs? I nearly came to the conclusion that it doesn’t, but now a different response is taking shape for me.

At this point I am going to narrow my discussion to projects designed in Revit Architecture, since it is the most commonly used program for architectural applications on BIM projects. And the fact is that a properly constructed Revit model already contains much of the information that wall and ceiling estimators spend all those hours (re)creating. In a properly detailed Revit model, many wall and ceiling scope items are already described, and many quantities can be generated automatically.

In fact, several programs already exist that can be used to perform automated quantity takeoff from Revit models. Two such programs that I have used are Solibri Model Checker from Solibri and Quantity Takeoff (QTO) from Autodesk. In both programs, you export an intelligent file from the Revit model to the takeoff program. You set the parameters of your takeoff, and the quantity takeoff is done automatically by the program.

So let me explicitly state my basic point: Our current methods of performing quantity takeoff are out of date. Technology that can perform accurate, detailed quantity takeoff automatically is available right now. Take a minute to think about how revolutionary this is for the typical wall and ceiling contractor’s bidding process. Think about a world where you open a file, review it, click a button, and your takeoff is done. That world is already here.

That’s the good news. Now it’s time for the bad news.


Before you dream of never having to spend days and days dragging a mouse again, let me point out some significant problems.

First, Revit models can be difficult or impossible to obtain during the bidding process. Whenever I see a set of plans with the telltale .rvt file extension (meaning that the project was drawn in Revit), I request a copy of the model. So far I have received access to a copy of only one model during the bidding process—out of six or seven that I have requested. For a variety of reasons, architects are still very skittish about releasing Revit files during the bidding process. Many projects are still being drawn in CAD anyway, in which case my proposed approach of using intelligent programming would not apply.

Second, Revit models are not always properly drawn. For example, in order to properly take off the gypsum wallboard partitions in a project, you have to be able to identify them correctly, and then you have to be able to quantify their length and height. In theory, all this information is included in the Revit model. However, in practice, this may not be the case. Perimeter furring may be modeled as part of the curtain wall, or the overall height of a gypsum wallboard partition may be incorrectly modeled. Obviously this means that your automatically generated takeoff is not going to be accurate.

And this is precisely where wall and ceiling contractors become relevant to the BIM design process. Why should architects give us access to copies of their Revit models during bidding? Because we need the models to do very specific things, such as showing accurate wall and ceiling tags and correctly modeled heights for walls and ceilings. This means that we are actually doing quality control for the architect during the bidding process by helping him or her identify problems and inaccuracies in the model. Because of our specific needs, contractor involvement in the model inherently involves quality control, and this provides incentive for the architect to share the model with us. If you objected that you don’t want to spend resources identifying problems with the Revit model, I would respond: How is this significantly different from the current RFI process during bidding?

Now you may be thinking that if you have to review the Revit model prior to performing your takeoff, bidding in BIM is not worth the effort. But stay with me just a minute longer. Some programs such as Solibri Model Checker automate the review of the model as well as automate the takeoff. In Solibri Model Checker I can first make the program identify all wall objects not drawn from deck to deck. This is called a “rule.” After I enter the rule, the program automatically checks all the wall objects in the model and highlights the wall objects that are not drawn from deck to deck. Once I identify the incorrectly drawn wall heights, I can correct them manually and proceed to take them off, automatically, by using a different tab in the same program.

Third, BIM takeoff software is expensive. Not only is the software costly (actual cost varies greatly depending on the program or programs you purchase), but you may need to upgrade your computer hardware as well. However, the biggest investment is going to be personnel training. I see no way around this. Not only do you have up-front costs for software, and possibly hardware, but you will have to invest time and money in training if you want to use this approach.

Fourth, BIM takeoff software is not easy to use. Popular takeoff programs are easy to learn and
use. The tradeoff for a program intelligent enough to automatically perform takeoff is that it is more difficult to learn. For example, since you are not manually recreating the partition schedule, you have to be able to manipulate the partition schedule that the architect has already created in Revit. This requires more skill from the program user, but the payoff is that you don’t have to recreate the partition schedule in your takeoff program.
The Way Forward
Now is the time for the wall and ceiling industry to lead the way in creating modern quantity takeoff methods. The necessary technology is already here, and the industry is already excited about it. Many architects and general contractors, as well as some trade contractors, are using the new technology. What is lacking is a clear vision for using this technology in everyday wall and ceiling estimating applications. Let me suggest some steps that can be taken toward making automated quantity takeoff an everyday reality for wall and ceiling contractors.
First, nationwide BIM standards need to be developed for our trade. An official industry task force would be the most efficient means of developing these standards, and the Association of the Wall and Ceiling Industry will take a leading role in bringing together contractors, manufacturers, architects and software vendors to create such a task force. We don’t need to be trailblazers here, since the concrete and structural steel industries have already developed BIM standards for their trades. The buildingSMART alliance™ is already working on developing national BIM standards, so the proposed wall and ceiling industry task force will likely be able to work together with them. Also, the SEEK database from Autodesk gives Revit Architecture users access to industry-specific resources, so there is already a simple way for architects to use resources that our industry develops.

The BIM standards for the wall and ceiling industry should address certain requirements that are necessary in order for our trade to use the models. Wall objects need to be tagged accurately, and wall heights need to be modeled properly. Ceilings need to be modeled at the correct height and clearly labeled by type. If the wall and ceiling industry could generate standards that include the key information points needed by our trade, and if we could get architects and general contractors to refer to our standards as they build their models, we could have a productive, model-based conversation going on among designers, general contractors and trade contractors. The wall and ceiling industry has an opportunity here to help create trade-friendly modeling.

Second, we need to encourage architects to release copies of their models during bidding. Right now the requests for copies of the models are too scattered and disorganized. Wall and ceiling organizations should corporately begin to create industry pressure for access to these documents. We need to capture the interest of architectural firms and general contractors who can see the benefit of allowing trade contractors to regularly bid in BIM. Once we can get a few respected architectural and general contracting firms to work together with us on bidding in BIM, others will follow. But wall and ceiling organizations need to get actively involved to get the process started.

Last, we need to develop a viable workflow for estimating in BIM. We all know how the current workflow goes: The architect exports his drawings to PDF files, sends them to the general contractor, and the general contractor sends out an invitation to the trade contractors with a link to the PDF files. Most wall and ceiling contractors are accustomed to this workflow by now. What we don’t know is what the new workflow will look like. What file format—.rvt, .dwf, .ifc—will be broadcast? Our industry needs to decide which format works best for all parties. How much editing ability should trade contractors have? All? Some? None? What makes this question even more complex is that some file formats limit the options you have for takeoff programs. For example, .dwf is a great format because it is read-only and still has automated takeoff capabilities. However, these files will lead you to use Autodesk’s QTO program, and the troubleshooting capabilities of that program are limited.

For bidding in BIM to become a reality, our industry needs to lead the way in developing a new workflow. That way we can demonstrate what we are trying to accomplish and how we intend to accomplish it, which will go a long way toward encouraging architects and general contractors to work with us.

While BIM for bidding is very close to becoming an everyday reality, it is also very far away from becoming an everyday reality. We obviously have a lot of work to do to make this new technology part of our everyday bidding processes. However, because of the number and size of the architectural and general contracting firms that have already made the switch to BIM, I am convinced that this change will happen, and I firmly believe that the wall and ceiling industry should take the lead in making it a reality.

Steve Clark is an estimator at Cord Contracting in Woodbury, N.Y.

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