BIM: What exactly does it mean? .... Contractors Guide

This Contractor’s Guide is intended to assist in determining how to get started with
using Building Information Modeling (BIM) or Virtual Design and Construction
(VDC). Though focused on buildings, much of the guide is applicable to all types of
construction. The guide provides answers to many of the common questions asked
by both general and specialty contractors who believe that with the use of improved
technologies this process is the way of the future and are trying to determine where to
start in their own organization.



Building Information Modeling is the development and use of a computer software
model to simulate the construction and operation of a facility. The resulting model, a
Building Information Model, is a data-rich, object-oriented, intelligent and parametric
digital representation of the facility, from which views and data appropriate to various
users’ needs can be extracted and analyzed to generate information that can be used to
make decisions and improve the process of delivering the facility.

The process of using BIM models to improve the planni
process is increasingly being referred to as Virtual Design and Construction (VDC).
ng, design and construction

The New “Tool” The extended use of 3D intelligent design (models) has led to references
to terms such as 4D (adding time to the model) and 5D (adding quantities and cost of
materials) and on and on from there. Perhaps a simpler way is to think of the 3D
model as a “tool;” then the applications of its use throughout the planning, design,
construction and facility operation processes are almost infi nite. Based on this, when
coordinating construction sequencing by integrating schedule data with the model data
and calling it “4D”, or doing the same when using the model data to quantify materials
and apply cost information and calling it “5D,” seems arbitrary since these are just
two of the many applications of how the 3D “tool” can be used to improve all of the
processes. Therefore, rather than continuing on with this numbering (6D, 7D, etc.)
there is a growing trend to refer to all of the extended applications using the 3D tool
as “XD.”

Benefits to the contractors using BIM include:

• The ability to identify collisions (e.g., identifying ductwork running into structure members)
• The ability to visualize what is to be built in a simulated environment
• Fewer errors and corrections in the field
• Higher reliability of expected fi eld conditions, allowing for opportunity to do more
• prefabrication of materials offsite, which is usually a higher quality at a lower cost
• The ability to do more “what if” scenarios, such as looking at various sequencing options, site logistics, hoisting alternatives, cost, etc.
• The ability for non-technical people (clients, users, etc.) to visualize the end product
• Fewer callbacks and thus, lower warranty costs

“Who should pay for the model?” The most common question asked is, “Who’s receiving
the most benefi t and therefore should bear the cost of developing the model?” The
growing consensus is that everyone benefi ts and therefore everyone should bear some
of the cost. It is generally accepted that there is an initial cost and loss of productivity
while obtaining the necessary resources as fi rms go through the initial learning curve.
Contractors who have made it through this initial learning curve (on average between
6 and 18 months) experience the benefi ts, including improvements in productivity,
lower warranty costs, fewer fi eld errors and corrections, etc. and for a period of time,
a competitive marketing advantage. These benefi ts offset the costs and over time may
actually reduce them.

2D Conversions versus 3D Designs (a factor throughout the guide) This issue is a
critical one for contractors, and is likely to remain until such time that the majority of
design fi rms are designing using 3D design software. Projects using BIM are either
designed in 3D or designed in 2D and converted into 3D. Since most of today’s issues
are signifi cantly affected by which of these two scenarios is applicable, this distinction
is made throughout this entire guide. (For example, answering the question about the
cost of the model is greatly affected by whether or not the design is being done in 2D
and someone has to invest the time in doing a conversion. If the design is done using
intelligent 3D design software, there is no conversion and the contractor’s ability to
start using the “tool” is immediate and much less expensive to the contractor.)

Overview of the Guide The guide addresses the following:

• The 3D vs. Conversion Issue—addressed as it applies throughout each section of the document
• Collaboration and BIM Tools—groups and highlights the basic software tools that support BIM
• The BIM Process: How is it to be conducted?—explains what the BIM process looks like
• Clarifi cation of Responsibilities—highlights fundamental responsibilities relative to the BIM process
• Risk Management—identifi es the major areas that contractors should begin to think about

What does it mean to “use” BIM? What defines a project “using BIM”… It is not
necessary to model the entire project to be “using BIM” on a project. In fact, many
contractors are involved in projects with intelligent models without realizing it. The
designer and/or some of the suppliers and specialty contractors may be using models
for their own benefi t and not sharing the information with the other members of the
team. Use of the BIM “tool” is encouraged even if it is only available for a portion of
the project, such as the structural steel or the mechanical systems.

Also, contractors are making use of intelligent models for portions of the project scope

to assist them with many of their traditional activities. Many of these “partial uses” of

BIM include:

• Assisting with scoping during bidding and purchasing
• Reviewing portions of the scope for analyses such as value engineering
• Coordinating construction sequencing (even if just for two trades)
• Demonstrating project approaches during marketing presentations

Get Started Now BIM or VDC clearly appear to be the future of our industry. For
some contractors, the future is now. Contractors have a choice. For those that choose
to start now, this guide offers a place to begin. However, even if you decide to wait,
every contractor is encouraged to at least start familiarizing itself with the key terms,
the acronyms (see the Glossary) and the current available software applications.
Experience has shown that having an awareness of all of these will provide a good
framework for gathering knowledge on the subject, and better prepare you when you
are ready to get started. For those who are ready now, let’s get started…