Through a computer screen image, building information modeling software ensures everything fits before construction is started.


Building information modeling, often called BIM, is a revolutionary process helping to improve the efficiency and accuracy of the construction design and installation process. If you haven’t heard about this industry-changing process from your customers or industry peers, you probably will within the next 12 months.

For the past few years, architects, engineers and builders have been evangelizing the merits of BIM. Additionally, most major industry groups have identified BIM and compliance as the next evolution in how mechanical, electrical, and plumbing engineers and contractors will work on projects, bringing many improvements and efficiencies to an industry that needs them badly.

One of the main reasons why building information modeling is receiving so much attention is that the core elements and its inherent value offer significant benefits to everyone in the construction process. What’s more, these benefits are equally distributed to each stakeholder, starting from the beginning of the design to when the building is completed and handed over to the owner.

Here’s what all of this means to sheet metal contractors, in terms of best practices and information you can use to plan your entry into BIM.

Building information modeling software lets contractors and owners see problems before a structure is built. In this example, the ductwork runs into gas lines.

What is it?

Basically, BIM is an integrated process that allows architects, engineers and builders to explore a project digitally, on a computer screen, before it is even built. This ensures building projects are designed, built and managed using coordinated, consistent information through the design and construction processes. With BIM, the old approach involving multiple tiers of redrawing the model as the project progressed through its phases and passed from one trade to the next becomes a thing of the past.

It provides a process for generating, sharing and managing building data during a project lifecycle, from initial design to facilities management. It uses 3-D, real-time, intelligent models and encompasses building geometry, spatial relationships, geographic information, and quantities and properties of building components.

The basic element of BIM is the ability for multiple trades to work with coordinated and consistent design models. The model begins with the design team - the architects, surveyors, consulting engineers and others. It then passes to the contractors and subcontractors who add their knowledge and data, and finally on to the owner who may provide additional input or updates.

Ultimately, the rich, detailed data within the model can be downloaded all of the way through to the plasma cutter.

The result of this process greatly reduces the information loss that occurs when a new team takes over a project. BIM can also increase field productivity of all subcontractors significantly. The key here is the use of “clash detection,” which drastically reduces the amount of time spent on coordination by providing automatic notification of conflicts detected among any of the mechanical, electrical or plumbing systems and the structure. In addition, building information modeling delivers extensive information to owners of complex structures - far beyond the level of information they are currently accustomed to receiving.

What are the benefits?

BIM is causing a revolution in computer-aided design and the construction industry as a whole because of the enormous efficiencies it introduces in every phase of a project. Many industry analysts anticipate that the adoption of BIM will be the most significant new technology change since the transition of paper design to two-dimensional digital data years ago.

To maximize its impact, every member of the construction project must be an active participant in the process. When this happens, you can realize a number of major benefits, including:

• Increased field productivity

• Decreased duplication of drawings

• A more efficient request-for-information process

• Improved visualization, simulation and analysis

• Construction documentation coordination and automatic clash detection

• Ability to embed and link vital information such as specific materials vendors, location of details and quantities required for estimation, and tendering

• Increased speed of delivery

• Reduced costs

• Increased environmental stewardship

• Increased efficiencies in ordering materials and scheduling

•Improved site safety

The problem with the gas lines and ductwork has been resolved.

Best practices

To achieve these benefits in your sheet metal business, it’s essential to follow best practices for BIM. The biggest advantage to a sheet metal contractor is using building information modeling 3-D clash detection - a new way to achieve trades coordination.

It begins by first having the steel model and architectural elements - ceilings and walls - in a 3-D model. The coordination schedule is then developed. For each area of the building, general routing areas of systems are discussed and agreed upon based on priority.

The various contractors - plumbing, piping, sheet metal, electrical and fire protection - then create 3-D drawings of their systems, which are posted onto a Web site along with the steel and architectural models.

The clash-detection capability of BIM automatically identifies conflicts and generates reports detailing each clash, its location and the systems involved. These reports are then circulated back to the team for review prior to the coordination meeting. During this meeting, the team is able to view the model, see the specific problems, and discuss how to re-route systems to eliminate them. Those systems are then redrawn and the process continues until all clashes are resolved.

Depending on project complexity, problems could be eliminated in as little as two meetings, dramatically simplifying the coordination process. And once the area is clash free, the model is signed off on and locked so that no further changes can be made. The drawings can then be downloaded directly to fabrication equipment, eliminating manual data entry and the human errors associated with it.

Real-time decisions

The 3-D visuals enabled by BIM allow team members to make real-time decisions throughout the coordination process. It also facilitates active involvement by the architect, engineer and owner, which is critical to ensure that the process runs smoothly. Experience shows that owners and engineers can more easily understand why some structural changes, such as lowering ceilings, need to be made when all of the systems are viewed in 3-D. As an initial entry point to BIM and 3-D modeling, products such as Autodesk’s Navisworks Manage provide an excellent first step for model aggregation and visualization. The project phase that Navisworks Manage best addresses is real-time team collaboration. Such programs help all of the construction team, from owner to the sheet metal contractor, by reducing change orders and project waste.

Through effective identification, inspection and reporting of potential interferences in a 3-D project model, BIM software programs reduce error-prone manual checking and enables users to check time and space coordination, improving site and workflow planning.

Construction schedules can be built to follow a completed coordination model, making scheduling easier for the general contractor or construction manager. Having a 3-D model makes it easy to understand the precise order that each system needs to be installed, which is critical to maintain the project’s integrity. The project can simply be assembled like a puzzle. It also allows the sheet metal contractor to release the drawings for fabrication based on just-in-time practices without the fear that work will be interrupted or shifted to unplanned areas due to system interferences. In addition, the contractor can deliver only the material to the site as it is needed for installation, eliminating the hassle and potential for loss from moving ductwork multiple times on site because construction areas are not ready. Instead, material is shipped by area and installed shortly after delivery.

A report generated by Navisworks Manage that shows where problems exist.

Less interference

Eliminating interferences during field installation reduces interruptions, which allows you to estimate field productivity more accurately and complete projects on schedule. Since the locked model is stored on site, should any clashes occur, the model can be referenced quickly to determine which trade is in error so immediate corrections can be made without bringing work in the affected area to a complete halt. General contractors especially appreciate this since issues can be resolved with little or no involvement on their part.

Through more efficient team coordination, accurate scheduling, and clash-free installation, BIM-driven jobs typically can be built much quicker than jobs delivered the old-fashioned way. It allows for better trade collaboration and sequencing and eliminates the need to stack trades, which also negatively affects every subcontractor’s productivity. And the locked 3-D model virtually eliminates the need for change orders due to errors in coordination. In fact, if the BIM process is followed correctly, you should have no change orders due to coordination issues.

BIM ensures accuracy throughout the process, and eliminates the need to redo final drawings based on actual installation. Essentially, barring changes to the structure itself, the locked 3-D model can be submitted before a single piece of duct is installed. Experience also shows that BIM projects have less clutter, less congestion, and allow for more efficient use of lifts, decreasing direct costs and providing a much safer job for all trades.

The future

Building information modeling requires a significant shift in the current workflow and processes used in sheet metal fabrication. Stepping forward into the revolution should be done in steps. A contractor’s first BIM project should be on the scale that the contractor is prepared to understand and manage.

Process change won’t happen overnight. But it will happen soon. Once a few final pieces are in place, taking a single model from initial design to fabrication, industry-wide BIM adoption will be in full throttle.

Matt Cramer is president of Dee Cramer Inc., a 71-year-old sheet metal and HVAC contractor based in Holly, Mich., with extensive experience in building information modeling. He can be reached by e-mail at mattc@deecramer.com. Dave E. Quigley, who holds a master’s in business administration, is director of product and business development at EastCoast CAD/CAM in Littleton, Mass. Contact him at dquigley@eccadcam.com.