Why BIM Doesn’t Work as an Independent Cost Estimator

BIM (building information modeling) is a well-recognized tool for the support of cost estimation and information exchange between the parties involved in planning, decision-making, and execution of construction projects. The most widely cited goals of using BIM are to reduce construction costs, eliminate construction conflicts and speed up the timeline of construction projects, however, leveraged by professionals with on-the-ground experience and insight, the technology has the capacity to provide even greater benefits.

Using BIM in the process of cost estimation enables the preparation of more accurate estimates as the whole set of data on the project is collected in a unique software package. Some software has the capacity to automatically render full or partial bills of materials for construction costs. However, as with any technology, issues may arise when the data rendered by BIM is not tempered by the knowledge and critical thinking of skilled professionals with real-life experience. Here are the risks and challenges associated with the use of BIM software as an independent cost estimator without the benefit of insight and analysis by experts with experience on the ground at construction sites.

Construction costs

Theoretically, using BIM in a construction project would provide an idea of what the total project should entail as far as expense. In reality, however, an estimate rendered by BIM alone can’t reflect the real cost of the project. For example, BIM won’t give you actual price variations on materials costs due to continually changing markets, and can’t factor in variables like changes in fuel costs, disruptions to the supply chain, congested work areas, performing work out of sequence. BIM alone is also unable to reconcile the range of costs associated with project elements that are not yet determined or that are subject to change.

Teams must be technology savvy

BIM makes it possible to reduce construction costs significantly. However, this can’t happen if project design and construction teams aren’t knowledgeable about the capabilities as well as the limitations of the technology. The quality of the data rendered by BIM is only as good as the quality of data that is entered into its computations, and the ability of the professionals interpreting that data to account for variables that the software can’t predict or address.

Design errors

BIM provides a 3D model and can provide a cost analysis of whatever specifications you enter into the software. It does not analyze whether those specifications are realistic, or whether they are the best option for the project. For example, BIM will build a 3D model of a theme park or sports complex using whatever materials are entered into the calculation — but it can’t analyze whether those materials work well together, or foresee if one of those materials is in short supply and therefore much more expensive than it was before. It can’t predict how a chosen material will interact with local conditions like climate and precipitation or suggest an alternative material as more durable or cost-effective.

BIM is an extraordinarily useful tool, but the nuances of complex construction projects require the skill of expert professionals. Thankfully, engaging an expert with construction experience can help check and interpret the results rendered by BIM.

Final thoughts

At its most basic level, BIM enables developers, architects, and contractors to visualize a structure virtually and gather key information such as the quantities of construction materials. The BIM-based cost calculation process trims the time required to make a thorough cost estimate, as it can use the data from the building’s virtual model.
BIM, therefore, is a highly valuable tool to a cost estimator, but it is not sufficient in and of itself, and it can’t replace the skill and insight of seasoned professionals with on-the-ground experience in the building trades. Its value is directly related to its use by qualified experts who can fill in the gaps that no software can address with real-time knowledge and the insight of years of experience.

Willis Construction Consulting, a premier construction services solutions firm, counts BIM among its repertoire of tools and resources leveraged with expert insight to advise owners and developers on complex construction project budgets, logistics, site, and materials selection, cost management, and more. Get in touch today for more information on how we provide accurate estimates from project conception through completion.

Image Credit: WinErrorFixer @ Creative Commons

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