What is BIM?

3D Floor Plan
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What is BIM?  That is an excellent question, and the answer seems to vary, depending on who is actually responding to the question.

Technically, 'BIM' is an acronym that stands for Building Information Modeling, with a Wikipedia definition of: "BIM is a process involving the generation and management of digital representations of physical and functional characteristics of a facility.  The resulting building information models become shared knowledge resources to support decision-making about a facility from the earliest conceptual stages, through design and construction, through its operational and eventual demolition."

The difference between BIM and Computer-Aided Drafting (CAD) is that BIM uses parametric models that know what they are.  A wall in BIM is not represented as two 2D lines as it is in CAD:  It is a studded gypsum wall of a finite height and width that even contains an 'R' value used to define its heat transfer properties.  If you move the wall in the 3D model, it will show up as moved in all views and sheets. In BIM, you are building a smart 3D model that is not only a digital represenation of the physical building, but a BIM model that contains engineering data that can be used for: lighting analysis, heat transfer calculations, warranty data, cost, etc.  If BIM is used correctly, you can use it for door/window/equipment inventories, construction cost, cost center tracking, and even reliably decide whether your upcoming renovation will require a new air handler or larger heat pumps (and if they'll fit through the mechanical room door).

Due to different budgets, needs, and expectations, what a Building Owner and their users want out of a new building, and what they ultimately get, are two very different things.

The same thought process can be applied to Building Information Modeling.

Through experience, we have found that the expectation of what 'BIM' is depends on who you represent:

     - Building Owner

     - Design Team (Building Owner Representatives, Architect, Engineers)

     - General Contractor

     - Building Trades Contractors

     - End User (Building Owner/Facilities Department)

To level expectations and to ensure everybody is on the same page at the beginning of a project, it is of most use to start at the end of the project, and work our way back:

1. What would the End User (Building Owner/Facilities Department) like to walk away with at the completion of the project. What are the contracted deliverables?

     - A fully-engineered 3D BIM model used to design and construct the building?

     - Manufacturer/warranty/cost information within 3D model for each component within the building?

     -  What are we hoping to accomplish, on a daily basis, with the defined finished product?

2. What will it take for the Building Trades Contractors to install the physical items?

     - Who is modeling the trades content in the model?

     - Is the 3D model used to create installation and/or shop drawings?

     - Is a robotic total station utilizing coordinates from the model used in the field?

3. Can the General Contractor maintain costs and manage expectations?

     - Can the designs be physically installed in the walls and above the ceilings?

     - Is there enough time built into the schedule to adequately allow for installation discussion AND modeling coordination?

     - Are the costs and experience associated with the high-tech nature of the project captured?

4. Is the Design Team designing/engineering while utilizing a suitable BIM program?

     - Will the 3D model be released to the General Contractor for use in their coordination/installation efforts?

     - Will the architect and engineers coordinate their designs before handing it to the General Contractor?

     - Is the Architect's model complete with component information before transmittal to the General Contractor?

     - Who makes Supplemental Information (SI) and Request for Information (RFI) changes to the model after it's handed to the General Contractor?

5. How do I (Building Owner) tell the Design Team what I truly want, and communicate that with terminology that is consistent across the industry?

     - Have I researched what 'BIM' is and realize what I'm asking for?

     - Have I realized that the project schedule will be different than what I am traditionally accustomed to?

     - The end result will be a product that is useful throughout the building's life expectancy and will give us incredible amounts of useful information. Will our team know how to use it?

     - Have I realized that I will need to budget in-house resources to operate and maintain the 3D building model, as well as invest in software/hardware for the life of the building?


BIM, when utilized to its fullest extent, is an incredibly useful tool that can save materials, energy, time, and money.  It is a tool in every sense of the word and should be treated as such.  If it is not maintained or used correctly, it will be a financial drain, dangerous to operations, and eventually become unusable.

Getting your team to discuss all of the items above will result in a common understanding of what the delivered product will be.  BIM is here to stay because it has the ability to save the Building Owner and their Facilities Departments installation materials, energy, time, and money throughout the course of the building’s life.

If you would like to discuss your upcoming project, or have general questions about the BIM process, please contact us at: info@finaldraftcad.com



Marisol's picture

I'm about to make an argument that may seem out of place and it shuold sound silly, but I'm getting to a much larger problem that I promise to tie together at the end.I fail to see how calling BIM a technology platform actually helps anything? First, let's look at your comment: Why not “construction BIM”, “design BIM”, “facilities BIM” and I would like to propose “Geo-BIM” for non-building, infrastructure related projects, above and below ground. Because I could draw a warehouse building with a carpenters pencil, cut it out to exact dimensions with a child's round tipped safety scissors, and paste it together with Elmer's glue. Technically it's a representation of a building, it has exact dimensions so it contains information, and since I glued all the pieces together it's a model. I now have paper BIM! Since this was designed, constructed and it represents a facility and we can place paper equipment inside it, it's construction BIM, design BIM, and facilities BIM!!! My technology was paper, pencil, and glue. You might argue that this information needs to be digital to be BIM. I'll take a few digital photos of my paper model and link it into a document. You next might state that a few pictures can't be BIM. Actually, I currently have software on my computer that can take the information from a few photos and create a 3D point cloud from it. Few people would argue that Point Cloud data of a building model to scale can't be considered BIM. So a pencil, paper and scissors is now, officially, been made part of the BIM process.Excel spread sheets, scanned hand drawn documents, SketchUp models they can all be BIM and technically fall into any of these categories if done correctly.Our problem isn't the categorization of BIM, it's the use of the term period. BIM has become a storage area for every piece of digital information that can be tied into a model. It's been called a process because so many things are thought of and brought into a digital model that anything, including a paper model, can now be tied back into the process of BIM.We need to stop using the term BIM altogether. It's simply a term developed to describe a building model that morphed into everything related to computers that was different than how we did them before computers. I strongly believe that BIM is now just us doing our jobs. The use of the term BIM.. I believe shuold be obsolete. When describing what we do, we shuold be stating that I'm using Revit to explorer our design options; I use Navisworks to coordinate our different models; even I practice Architecture is better as it describes what we do better than a catch all term like BIM. I don't know many people that practice BIM as their duties can be quantified better by actual architectural, construction & even IT terms.