Cost Estimation (Quantity Take-off)

Description:

A process in which BIM can be used to assist in the generation of accurate quantity take-offs and cost estimates throughout the lifecycle of a project. This process allows the project team to see the cost effects of their changes, during all phases of the project, which can help curb excessive budget overruns due to project modifications. Specifically, BIM can provide cost effects of additions and modifications, with potential to save time and money and is most beneficial in the early design stages of a project.

Potential Value:

  • Precisely quantify modeled materials
  • Quickly generate quantities to assist in the decision making process
  • Generate more cost estimates at a faster rate
  • Better visual representation of project and construction elements that must be estimated
  • Provide cost information to the owner during the early decision making phase of design and throughout the lifecycle, including changes during construction
  • Saves estimator's time by reducing quantity take-off time
  • Allows estimator's to focus on more value adding activities in estimating such as: identifying construction assemblies, generating pricing and factoring risks, which are essential for high quality estimates
  • Added to a construction schedule (such as a 4D Model), a BIM developed cost estimate can help track budgets throughout construction
  • Easier exploration of different design options and concepts within the owner's budget
  • Quickly determine costs of specific objects
  • Easier to strain new estimators through this highly visual process

Resources Required:

  • Model-based estimating software
  • Design authoring software
  • Accurately built design model
  • Cost data (Including Masterformat and Uniformat data)

Team Competencies Required:

  • Ability to define specific design modeling procedures which yield accurate quantity take-off information
  • Ability to identify quantities for the appropriate estimating level (e.g. ROM, SF, etc.) upfront
  • Ability to manipulate models to acquire quantities usable for estimation

Selected Resources:

  • Lee, H., Lee, Kim, J. (2008). A cost-based interior design decision support system for large-scale housing projects, ITcon Vol. 13, Pg. 20-38, http://www.itcon.org/2008/2
  • Autodesk Revit. (2007) "BIM and Cost Estimating." Press release. Autodesk. 11 Sept. 2008. http://images.autodesk.com/adsk/files/bim_cost_estimating_jan07_1_.pdf
  • Dean, R. P., and McClendon, S. (2007). "Specifying and Cost Estimating with BIM." ARCHI TECH. Apr. 2007. ARCHI TECH. 13 Sept. 2008. http://www.architechmag.com/articles/detail.aspx?contentid=3624.
  • Khemlani, L. (2006). "Visual Estimating: Extending BIM to Construction." AEC Bytes. 21 Mar. 2006. 13 Sept. 2008. http://www.aecbytes.com/buildingthefuture/2006/visualestimating.html
  • Buckley, B. (2008). "BIM Cost Management." California Construction. June 2008. 13 Sept. 2008.
  • Manning, R.; Messner, J. (2008). Case studies in BIM implementation for programming of healthcare facilities, ITcon Vol. 13, Special Issue Case studies of BIM use, Pg. 246-257, http://www.itcon.org/2008/18
  • Shen Z, Issa R R A (2010) Quantitative evaluation of the BIM-assisted construction detailed cost estimates, Journal of Information Technology in Construction (ITcon), Vol. 15, pg. 234-257, http://www.itcon.org/2010/18
  • McCuen, T. (2009, November 18). Cost Estimating in BIM: The Fifth Dimension. Retrieved September 21, 2010, from Construction Advisor Today: http://constructionadvisortoday.com/2009/11/cost-estimating-in-bim-the-fifth-dimension.html