By Philip D. Larson

The benefits of Building Information Modeling (BIM) have been principally touted to non-residential construction in recent years. Most of these have been largely centered on initial marketing efforts showing a 3D model of the project, to time-lapsed depictions, to the ever popular “clash detection” (also known as 3D interference checking). In fact, according to the McGraw Hill Market Report in 2009, marketing scored “high/very high” by 49 per cent of those responding. Marketing was also ranked highest by architects rating the perceived benefits of BIM.
But the residential market can benefit from BIM as well, since the use of BIM is not the same thing to all people. Fundamentally, BIM is a graphical representation of a project developed by the use of 3D objects that can carry additional “intelligence”. Therefore, the real use is only limited by one’s imagination and interest.

Automating the Process
The home building industry is comprised of a wide range of individuals and companies that construct anywhere from just one or two homes per year, to as many as several thousand. But regardless of volume, at the heart of building each of these homes is the need to meet homeowners’ expectations; to deliver the quality that their budget can afford, and to complete in a timely manner.
Through BIM, contractors can take advantage of automatic count (each), length, and area calculations to develop detailed cost estimates, and even bills of material (BOM) for use on their projects, as well as detailed construction schedules.
Surprisingly enough, a BIM model does not always have to be a 3D or pictorial representation of a project, in this case a home, to be able to offer these benefits to the home builder; a BIM model can also be a tabular representation of a given project. However, the more sophisticated home builder who has capabilities of authoring a BIM model with products such as Revit Architecture from Autodesk (www.autodesk.ca) can also offer visualization capabilities.

Figure 1 depicts a 3D representation of a one-storey residence with an accessible kitchen. The residence itself can be broken down to Foundations, Superstructure (Floor and Roof Construction), Exterior Closure, Interior Construction, and in this specific case, by room.
The 2D plans for a standard kitchen layout would be fundamentally the same as that for an accessible kitchen, but through the use of BIM, items (objects) such as door handles and electrical switches, etc., could be substituted quickly to adapt each living space as necessary to not only develop a cost proposal, but a bill of materials as well.
As far as emerging standards go, the AIA Document E202TM – 2008, Building Information Modeling Protocol Exhibit, under paragraph 4.3 Model Element Table, where elements are represented by the Construction Specifications Institute (CSI) UniFormat TM classification system is an example of how the commercial industry is giving specific definition to what is expected in a BIM.
These same types of protocols can be easily adapted by the residential construction industry in adopting BIM in a more formal way. Quantitatively, home builders can significantly reduce the lengthiness and compilation of the BOM, reduce the risk of missing items, and therefore increase the accuracy and enable more realistic estimating of costs, and better estimates of time for construction.
In the example above for instance, Interior Construction can also be broken down to room by room where the floor, wall, and ceiling finishes can all be quickly calculated. Of course, the fastest and most accurate ways to perform these calculations is electronically either through a generic spreadsheet product, or through tools specifically made for estimating such as Timberline by Sage, or WinEst by WinEstimator, Inc. that also integrate with dedicated scheduling tools such as Microsoft Project or Primavera by Oracle.
The specifics of how to take advantage of BIM are really determined on a case by case basis. But be that as it may, the tools and technology are no longer obstacles, but a means to prioritize goals and determine ways to accomplish them effectively, thereby reducing costs to the homeowner while improving the home builder’s profitability.

Philip D. Larson, CCE CEP CPE PMP PSP FAACE FRICS, has been providing BIM consulting services with Project & Cost Control (PC2) since 1992. He is Past President of AACE International, a non-profit professional educational association founded in 1956, and the largest organization globally serving the entire spectrum of the cost and management profession. Currently serving as co-chair of AACE’s BIM Committee, Phil’s specific expertise has been to translate a BIM model into a detailed cost estimate, and then into a resource loaded construction schedule, facilitating the ability to build projects on time and on budget. He can be reached at drphil@att.net.