As BIM continues to gain traction within the industry, one of its components—5-D model-based estimating—has been responsible for significant innovation and automation. 

5-D BIM connects objects in the 3-D model to assemblies and components within an estimating database. Whenever a change is made to the model, the estimated costs can be easily—if not automatically—updated. This allows estimators to quickly see the cost implications of design changes throughout the project evolution, often referred to as iterative estimating.

When used to drive estimating best practices, 5-D BIM provides unprecedented efficiency, along with the flexibility and accuracy to turn around big estimates quickly, inform better decision-making and drive cost predictability. More importantly, 5-D BIM saves estimators time by avoiding tedious takeoff exercises and allows them to focus on more critical factors, such as risk mitigation and owner and subcontractor relationship management.

Post-Recession BIM Boom  
The economic downturn of the past decade actually played a significant role in accelerating the BIM evolution—and more specifically, model-based estimating. In the height of the downturn, money dropped out of the construction industry, project scaled way back and budgets waned. Accuracy, efficiency, transparency and predictability became necessities on the work that could move ahead post-recession. At the same time, many subcontractor and trade partners were embracing BIM for 3-D coordination and prefabrication.

Today, a perfect storm is building as more contractors are becoming aware of the benefits models can provide and linking them to model-based estimates and schedules. As a result, 5-D is beginning to find its stride within the industry.  

In fact, a 2015 Dodge Data & Analytics Smart Market Report, “Measuring the Impact of BIM on Complex Buildings,” reveals increasing recognition among general contractors, trade partners and owners regarding the positive impact of BIM-based estimates. According to the study, 42 percent of contractors report a high or very high impact from BIM on estimating, likely reflecting an increase in their hands-on role in the process.

Advances in estimating technology continue to improve and are breaking down barriers that have prevented more rapid adoption of model-based estimating.

General contractors typically report that models are very helpful for takeoff of high-quantity elements, such as structure, facade and MEP; however, 2-D plans are often referred to for detailed work, such as finishes and blocking. Traditionally, these tools acted independently of the estimating software managing assemblies and costs, which added time and risk to the estimating process. But new best-of-breed takeoff and estimating tools integrate the disparate nature of 2-D and 3-D quantity takeoff/costing, such that everything can be done within a unified environment.

Design data exchanges using BIM also have evolved considerably in the last several years. As 3-D has taken root as standard practice within the industry, more design teams are learning the benefits of creating constructible models. Several project experiences begin to demonstrate the immense benefits that can come from smart modeling practices, such as standard name and code conventions, intelligent trade and phase breakdowns within a model, and even lessons learned about what does not need to be modeled in order to help construction teams. 

Interoperability also has gained traction in the past several years, allowing contractors to focus more on their internal estimating practices instead of becoming experts in data management.

Benefits of Model-Based Estimating

Estimating with BIM enables general contractors and construction managers to increase efficiencies, win more work and maximize the profitability of projects.

Significant reduction in the amount of time it takes to perform quantity takeoffs and generate cost estimates. Using BIM, contractors say they can perform takeoffs three to five times faster than before, while cutting down the overall time to estimate projects by up to 50 percent. Further, it enables cost estimators to add more value in the early phases of planning, where cost calculations are more central to the iterative design process.

Expedited change management. Nothing is worse than finishing a large takeoff only to find out a new design or addendum has nullified the effort. Using BIM, design changes can be isolated and evaluated quickly, allowing estimators to reuse more of their previous work while focusing primarily on what has changed. This is especially useful with design-build and integrated project delivery.

A strong foundation for digital information exchange throughout the course of the project. The collaboration and communication that can occur via a digital model in the early phase often sets the entire project team at ease for more models that will come in to support coordination, scheduling/simulations and shop drawings.

How to Be Successful
As 5-D gains momentum and more projects require estimating in BIM, contractors and professional estimators are working to define a new process and capitalize on the opportunities available for improving cost estimating with BIM. Knowing where to start and how to incorporate model-based estimating will ensure success. 

Start now. Many contractors have reported a desire to get started after the models are refined and perfected. The truth is, few things in construction are ever perfect and the process is already being refined. Waiting too long to get started often results in missed opportunities.

Start small. Don’t anticipate unplugging the firm’s existing systems and making a change overnight. Learning to estimate with models often takes a year or more to get started. Work to identify ideal projects and teams so that proper opportunities can get the time and focus necessary to learn valuable lessons toward establishing a new process.

Make the most of what you get. Take what is available and leverage it for all that it is worth. At the same time, be prepared to augment the model-based takeoff with traditional methods wherever necessary. Look for an estimating system that makes it easy and efficient to blend 2-D and 3-D estimating practices.

Measure and share successes. It’s easy to fall back on familiar territory, especially when the clock is ticking and accuracy matters. Set some small measurable goals, such as “we want to use BIM for the structural scope on two projects,” and then celebrate the achievement once completed. Next, evolve the goal to a second or third scope. Sharing successes will help inform others in the company about the evolution that is taking place and is also likely to attract more millennial talent to the estimating team.

Technology matters. Don’t try to use yesterday’s tool for today’s challenge. Fully integrated cost planning and estimating applications are available and enable construction-caliber quantities, iterative cost planning, precise budget tracking and complete target cost analysis. Look for solutions that allow estimates to be created from a single knowledge base that has been designed to support 2-D and 3-D inputs, while supporting the movement toward a “single source of truth,” versus trying to maintain the same items and assemblies across multiple tools.

Establish a core team. Technology aside, people are a company’s most important asset. Assemble a team that is willing to pioneer new technologies and processes together to get the job done. Ensure the team has skill representation from estimating, constructability analysis and BIM management, and is united and committed to the cause of seeing things through. There will be hurdles along the way, and it is imperative that the team is strong enough to break through them.

With the right tools and team in place, it’s possible to unlock the full potential of 5-D BIM to shorten project schedules, lower costs, and improve the overall quality of design, construction and operation.  


Duane Gleason is product manager with Trimble’s General Contractor/Construction Management Division. For more information, visit gc.trimble.com.