Prefab poses new ways to assemble buildings

When the project team began planning construction of the Great Wolf Lodge in Perryville, they knew the project would include some extraordinary aspects and challenges. The developer of the 700-room hotel, resort, waterpark and entertainment center was determined to create an exceptional product and willing to engage in some leading-edge construction processes to achieve that goal.

The construction timeline for the six-story, 116,500-square-foot lodge, however, was tight.

“Great Wolf Lodge is a great client,” said Kurt Gavalier, Director of Offsite Construction at Turner Construction Company. “They have been pushing some boundaries of prefabrication over the years. We have done many of their jobs and included things like prefabricated bathroom pods.”

On the Perryville project, however, achieving a weather-tight structure by a set date was a priority. To make that deadline, Great Wolf and the construction team engaged in “prefabrication with a purpose,” Gavalier said.

“They partnered with a firm out of Philadelphia that specializes in modularized exterior walls and cold-formed metal framing solutions, and they prefabricated their entire roof structure,” he said. “It was like watching a wood-frame house go up with the panels and the roof trusses, but this was cold-formed metal framing for a commercial building. Great Wolf was adamant that this was needed to reduce the critical path and they were able to suck two months out of the schedule by prefabricating the roof truss structure and the exterior walls.”

Prefabrication isn’t a new operation in construction, but it is evolving.

Aided by BIM, companies are devising new ways to utilize off-site solutions to address labor shortages, meet critical path goals, and heighten both the quality and efficiency of installations. Some companies have developed highly specialized prefab offerings. Others are partnering and even merging to produce new, multi-disciplinary, prefabricated products.

Enthusiasts say that increased use and evolution of prefabrication is gradually changing the way we assemble buildings.

“One of the most impressive things I have seen up to this point is vertical, multi-trade racks,” said Langdon Lynch, Northeast Prefabrication Lead at DPR Construction. On one DPR project, “there were 10 vertical racks, 60 feet tall in four main shafts. The racks included all the conduit, all the HVAC, even the shaft walls and we lifted each rack over the building to install it. The superintendents were really thankful because that process saved time, improved safety and overall made the job easier.”

Rosendin Electric Co., which has created two prefabrication shops at warehouses near BWI and Dulles airports, has gained substantial experience in prefabricating and installing multi-trade racks, and collaborating with other trades on prefabricating products.

“Most of the coordination we have done has been with the mechanical trade, trying to share assemblies for pipe and conduit,” said Tony Esteve, Business Development Manager. “In some instances, we have gone to mechanical shops and worked there if they have big louver assemblies. We will do the wiring in their shop before an assembly gets put up on a wall.”

On a recent project, Rosendin discovered a different opportunity to collaborate with another trade and improve construction efficiency.

“We were doing duct banks,” Esteve said. “We typically have conduit in large assemblies, often 40 or 50 feet, for the underground duct banks coming off of the utility transformer into the building switchgear. We will have trenches dug and just drop the assembly in so they can be connected and you’re not putting pipe in the ground, section by section. One of the concrete trades asked if we could add a latch or clip on our strut assembly so they could put concrete boards or guards on it. That way, they wouldn’t have to build an assembly around our assembly. We said, absolutely!”

Multi-disciplinary prefab efforts are expanding to include additional trades, such as collaborations among MEP and structural steel contractors, Gavalier said.

“But some multi-disciplinary doesn’t necessarily mean dealing with multiple entities anymore,” he added. “There are some one-stop shops that do multi-disciplinary prefabrication. We’re seeing some of this happen because of M&A [merger and acquisition] in the industry. Mechanical, electrical, plumbing, fire protection, and fire alarm companies, in order to grow their revenues, are gobbling up their peers. One benefit is they are able to perform more services, more prefabrication inhouse and reduce the external complexity of coordination.”

Whether they’re collaborating with other trades or working on their own, many companies are gradually developing better, more efficient, more innovative prefab/offsite solutions.

Rosendin has refined its process of prefabricating medical headwalls — the array of connections mounted behind the head of a hospital bed to support electrical receptacles, nurse call and other communication systems and other functions.

“We prefabricate the headwalls to have all the conduits, whips and connections ready in a structure assembly so we can just set them and connect them as the building comes together,” said Brandon Jachimski, Operations Manager for Rosendin in Maryland.

To make the transportation and installation of often-large prefabricated items easier and more efficient, Rosendin also adopted a practice of sending everything out of its prefab shop on wheels and then improved the practice.

“We had a data center project where we had multi-story cable trays in 20- and 30-foot sections that we planned to roll in on carts.” Esteve said. “Someone suggested why don’t we get rid of the carts and put swivel wheels on the struts and we could just remove them after the racks were installed.”

That change led to just one hiccup.

“There was one punch list item that came back. The owner was confused about why a wheel was hanging off a strut assembly,” Esteve said.

At DPR, Sure Pod prefabricated bathrooms have become a signature, high-efficiency, high-quality item on some projects. At 20 Mass — a Washington, D.C. hotel designed around the concepts of green construction, healthy lifestyles and high tech — DPR installed 400 bathroom pods.

“It is an exceptionally nice product,” said Bill Hahner, Preconstruction Executive. “If you weren’t told, you would have no idea they were prefabricated units. And that’s one of our goals. The final product should meet the architect’s vision.”

Occasionally, prefabrication on a project becomes “fully volumetric,” Lynch said. “One of our latest projects [a pharmaceutical facility in New Jersey] was fully volumetric which is the holy grail for me. Think Lego bricks but the inside of them are completely finished — interior walls, all MEP is in place. You are just taking these blocks, setting them in place and making the final connections between them. Those projects aren’t common. They are the highest aspiration and they allow us to show the possibilities of what you can do with prefab.”

Advances in prefabrication/off-site solutions are also beginning to enable companies to apply the processes to items that aren’t identical.

“We are heading down a path of knowledge and wisdom and digital transformation where the item doesn’t have to be repeatable, it just has to be configurable,” Gavalier said. “Think about a multi-discipline rack that has ductwork and piping and conduit and steel going up in a hallway ceiling. It is something we have seen in healthcare for years. Every one of those racks going down the hallway is going to be slightly different. They are not repeatable, but they are configurable.”

Prefabrication shops, he said, are learning “how to modularize and configure systems, understand the nuances of the fabrication lines, and integrate those fabricated elements to create those slightly different products.”