By Garry Myers, Senior Estimator, Clark Construction Company
The old saying “You Get What You Pay For” can be applied to conceptual estimating in many cases. An estimate with little or no detail can lead to budget problems during the design process. The best opportunity to have the most impact on the overall project budget is early in the design process. It is through this experience that Clark Construction Company has adopted BIM technology to assist our pre-construction estimating efforts.
Our main estimating software, Sage Timberline, has been used predominately at Clark Construction for over ten years. Besides the databases we have built, we have the “Model Estimating” module -- which assists in developing conceptual estimates. The issue with conceptual estimates is whether there will be a clear understanding, by all the stakeholders, as to what the estimate includes and reflects, per the design. Since estimators can only construct a building through their minds’ eye, the main struggle is how to convey their assumptions and visually communicate an estimate.
To aid in the pre-construction process, we implemented the use of a 3D macro BIM/Conceptual estimating program called DProfiler by Beck Technology. DProfiler provides the benefit of conveying what the building will look like while maintaining a real-time link to the estimate. For most, a 3D model can be interpreted a lot more easily then 2D prints. For owners not familiar with an estimate or construction, the model is something they can see and understand easily.
For four years, Clark Construction Company has been using Sage Timberline in conjunction with DProfiler technology in developing pre-construction estimates. The following are several examples of how these BIM models were used and the benefits for developing the estimates in this manner.
Project 1- A question regularly asked of an Estimator is “How fast can you get the estimate done?” As we don’t always have the luxury of time, we have to fit the detail level of the estimate to the time allotted. During the past year, one of my estimates was for an eight-story building with two additional one-story buildings and almost 20 acres of site work. The estimate was required to be completed in one day.
The final deliverable estimate included a total of 29 pages, which included an 11-page narrative of assumptions, several picture views of the 3D model, and the balance of the estimate and summary pages. As the estimate quantities and pricing are linked to the BIM model, the step of manually entering quantities was eliminated. Updates to pricing were adjusted to fit this particular project. The program included a narrative template which linked the model information to the Word document. It would have been a struggle to pull together an estimate of this magnitude using traditional estimating methods. Although we found our estimating and 3D software invaluable in this instance, we would always prefer more time to ensure the best possible estimate for our client.
Project 2- This project involved a site of over 40 acres with more than 30 feet of elevation change from one side of the site to the other. Also, located on the site were to be a dozen buildings and structures. All of the site information was based on a hand-drawn sketch. Using the recently released Site Module in DProfiler we were able to import the site topography from Google Earth. We overlaid the sketch with the buildings and set the elevations, which allowed the program to calculate the required cut and fill. The buildings were modeled with BIM and all the data linked to cost information.
Providing a conceptual estimate for a project of this magnitude would be a challenge with any method, but use of this BIM tool allowed us to graphically show the owner a live view of how the buildings fit on the site and the resultant elevation issues. Being able to show potential issues visually, with retaining walls and site grading, was of great value and is hard to convey in the 2D world.
While architects have increasingly been adopting BIM programs, there are cases where they don’t design in BIM until the program has been validated through design and cost. In those cases, we have used the Macro BIM models to help define and solve problems relating to cost.
Project 3- We were hired as the CM on a project where our first estimate indicated the design, as drawn in 2D, was over budget. We modeled a total of three buildings based on designs supplied by the architect. Through this process, we were finally able to find a design that fit the owner’s budget. In this case and many others, we are not designing the building, but making a model of a sketch or drawing supplied by the architect. If lacking this information, we would build the model based on a narrative with as much or little information as available.
We also utilize several BIM tools that allow us to use the architect’s model, such as Revit and Vico. However, for estimating, these programs require far more detail and don’t link directly to cost in the manner we like. In short, it is much faster to model with a macro BIM program and build the estimate while building the 3D model.
The main difference is being able to create “high fidelity” cost information from a “low fidelity” model. With a macro BIM program, a building mass can be quickly drawn and clad, thereby creating quantities in a user-created database or estimating program. Likewise, site work boundaries, floor and columns lines, and interior fit-out can be further defined areas with parametric formulas, all while providing as much detail as desired. For those speaking with the owner, DProfiler can generate a development pro-forma or a conceptual energy analysis - which can provide a real differentiator.
An issue for most estimators is how the costing works in a particular program. Does the program force you to change your estimating methods? Or can it adapt to your company’s way of doing business? I use BIM with three different sources of cost data, each used in different circumstances. First is simply importing costs that I define in an Excel spreadsheet. Second is an R.S. Means database. Third, I’ll link with Sage Timberline Estimating.
Depending on the project and type of estimate needed, we have used all three methods of costing in DProfiler. Each has advantages:
1. the Excel can be modified easily to fit a unique job
2. the R.S. Means offers many pre-built building types, allowing adjustment for different locations around the country
3. the Timberline link allows seamless integration with our standard estimating methods.
As we use many programs in our department for estimating, I view them along with several databases - like tools in a toolbox, selecting the one that best fits the required estimate.
As for the difficulty of implementing these or other BIM programs, it requires dedication to achieve success. Learning how to build the models takes some training. Database work can be a little more involved. It is not much different than buying any estimating software program; it requires time to set it up and learn how it functions, but the results can provide enormous time savings and competitive advantages.
Garry Myers has over 30 years of experience estimating a wide range of projects, including self-performed work, and currently with a focus on preconstruction estimating services. Garry is also a member of ASPE Chapter #17, Detroit, Michigan and works for Clark Construction Company in Lansing, Michigan. Clark is one of the top 400 general contracting firms in the United States, providing a wide range of construction services.
This article courtesy of the American Society of Professional Estimators, which serves construction estimators by providing education, fellowship, and opportunity for professional development. For more information visit www.aspeninternational.org