Most in the construction industry should be familiar with building information modeling (BIM).
Autodesk defines it as “an intelligent 3-D model-based process that equips architecture, engineering, and construction professionals with the insight and tools to more efficiently plan, design, construct, and manage buildings and infrastructure.”
These days, it’s a must-have process.
Creating a BIM model
“Basically, the whole concept behind the BIM modeling is that, if you build the job with a computer before you go out and build it in real life, you’re finding all the clashes,” said Jeremiah Nieman, preconstruction manager, Collins Electrical Co. Inc., Stockton, Calif. “The guys in the field don’t have to stop progress of the job and write [requests for information] all the time because all of that has been done up front. The huge thing is, once you’ve done your clashes and got a model that everyone is comfortable with, you can build off of that. It’s a really great tool for us as contractors. The only time we get the owners or architects involved is when we can’t resolve clashes between trades.”
That is one instance when the collaboration between members of a construction team related to the BIM process comes into play. It can be a complicated process. Each project is different, and team members take different paths. There are no hard-and-fast rules about who creates BIM documents on any given project or if there will be BIM models. Often, multiple models are merged. Coordination is vital for BIM to be successful.
“The BIM process is very similar to the way it used to be, but now we have computers, which speed up that coordination process,” Nieman said. “We can model true-to-life objects in a BIM model with every trade in the ceiling—where the majority of your coordination happens—because that’s where the majority of your infrastructure and ductwork and plumbing is. We can see exactly what we have. Then we can move the duct work over 8 inches to clear the cable tray or move the cable tray to the other side of the corridor to clear conduit racks or plumbing.
“The advantage of using BIM is it reveals most of the problem areas, which can then be fixed. A lot of times in the modeling, we get into little hallways or along corridors where the mechanical, the electrical conduits, the plumbing and cable trays are shown in a corridor. We know that stuff is not going to fit in a normal corridor, so when we start modeling, we can say the electricians are going to take the left side of the corridors and the mechanical will go in the rooms next to the corridor. We do that really fast on a computer compared to actually sitting with a group of guys and writing it out on paper like it used to be,” he said.
It is common for architects to take the lead in drawing up the initial model, which others then work from, but that’s not always the case.
“I have come across situations where the architect was paid to do the plans and then the general [contractor] wanted to model the rest, but sometimes the model is driven by the owner and the general contractor,” said Dave Ayars, virtual design and construction/building information modeling, Morrow-Meadows Corp., City of Industry, Calif.
For example, on one renovation project, the general contractor used scanners and lasers to do its own model.
“The building had different ceiling heights and not much space to locate all the equipment,” said Ryan A. Doyle, architect and program coordinator at the NOW Institute, Culver City, Calif. “So, they brought in their own team to build upon our architectural model. They then worked with individual subcontractors to locate the mechanical, plumbing, fire protection and electrical equipment for the building and the cellar.”
On that same project, BIM also was helpful in coordinating with an entirely different entity: The Landmarks Preservation Commission of New York City. At the time, Doyle was an associate with COOKFOX Architects.
“We also needed to convince the board that the updated design for the building fit the character of the neighborhood,” he said. “The project involved replacing existing steel sash frames with higher performance contemporary aluminum windows. We were able to use BIM to model the new profiles, which showed the community board how close the look is to the original design.”
Opinions vary as to which models matter most.
“One of the most important things is the steel model,” Nieman said. “It’s really hard to coordinate a job until you have an actual steel model of what is going to be built. Usually, the steel model from the architect is not 100 percent accurate to what’s being built, so it’s very important that the steel guys get their model done first so that everyone can work around that, because we can’t ask the steel guy to move a beam for us.”
Sometimes, coordination between the construction team, using BIM, averts what could be a problematic situation.
“We had a hospital project a few years ago where there was just absolutely no way it was going to work unless we made a few structural changes in the steel,” Ayars said. “Because we caught it early on, we were able to have the structural engineer make those modifications because they hadn’t released the steel for fabrication. Once the steel’s released, it’s very hard to change any of the structural steel.”
BIM was helpful in documenting the structure of a 15-story, 1940s hybrid steel-and-concrete building in New York City.
“It had concrete-encased steel beams, which are a little uncommon,” Doyle said. “The structure in the building changed just about every floor. Sometimes the beam would be in a slightly different position on each level, and that was important to keep track of as we were going to cut holes in the slab to run mechanical or plumbing piping. We used BIM to study these conditions and produce all of our presentation and construction documents.”
Clearly, having a starting point—an architectural model—benefits the whole construction team. But what if you don’t have a model? Morrow-Meadows had two jobs with no architectural model. One was a renovation, and the other was new construction.
“We were still required to BIM model the projects, so it was an effort between us and the mechanical contractors to coordinate the complete jobs without having an actual building to coordinate around,” Nieman said.
To do both, structural models were used, which were provided and worked around. The lead contractor in the coordination effort used the 2-D architectural plans and extruded walls so they could have walls in their models as well.
Some contractors use a model to construct a physical mockup of a part of a project. Those mockups can be large or small.
On a project for the University of California, Merced, Collins Electrical Co. created a model of a 10-by-24-foot section of the project, then created a physical mockup based on the design. It was basically a full-sized structural model built to scale chiefly for study, testing or display. The project included three different types of roofing with different finishes. Samples of each were included in the physical mockup.
“What we prefer when doing a mockup is to begin with a computer, get all the dimensions and boxes we need, put it together in a model, then take that data and tell the guys in the field, ‘This is what you need to build that mockup,’” Nieman said. “Once the mockup is created, we can see if there’s anything we missed and deal with remarks or concerns. For example, dimensions or finishes the owner doesn’t like. Then we can change our model to match exactly what the owner wants, what the architect wants. We were able to take any critiques related to rooms or areas in the mockup, fix anything quickly, then enter that data into our models and just run from there. We could then build the rest of the project and know the quality was there because of that coordination.”
A new, virtual reality mockup makes the experience even more sophisticated.
“We are starting to virtually model the computer project with software that projects the space on a green screen,” Ayars said. “Wearing goggles, you can come in and virtually walk through the room, feel like you’re actually there. It’s cutting edge.”
Use of BIM also can escalate the process of a project by making prefabrication of project elements easier.
“When we use the BIM process, we get 3-D representation to make sure everyone’s materials, for example, a piece of switchgear or a panel, to fit,” Ayars said. “Then our prefab department can make assemblies. The guys in the field can look at our drawings and know exactly where to put those assemblies. It’s what we do to stay up with schedules, which get very aggressive. On job sites, especially in downtown Los Angeles, we can’t store a lot of material, so when I deliver material, I have to get that job installed that day. Knowing exactly what’s needed and where it will go makes that expedited installation possible.”
The word “expedited” is heard on most projects. Because processes that previously weren’t computerized now are accelerated, BIM can speed up the schedule.
“With BIM, we’re able to preplan and install quicker because the problems have been solved earlier,” Ayars said. “In the past, though, I used to have a month on the floor, and I now have two weeks. I have to have time to do the BIM modeling and coordination before construction starts, but sometimes the two schedules start squeezing together. I have to move some of my efforts from the construction schedule over into the coordination, preplanning and prefab side of things. I’m modeling the information from the owner, the designers and the engineering team. If they don’t have that information, it can delay the process, though, it doesn’t extend the schedule. It just compresses it.”
There’s the rub. No matter how helpful the model is or how well the construction team coordinates, at the end of the day, the most coordination is required just to get the job done on time, just like it always has been.