Prefab on steroids

By Timothy Allinson, P.E.,
Murray Co., Long Beach, Calif.

In July, I was fortunate enough to take a trip to Cincinnati for a two day peer group meeting orchestrated by FMI, the Management Consulting Corporation. The peer group consisted of seven mechanical contractors of similar size as my own firm. Its purpose was to provide a forum to discuss industry trends, successes, failures, lessons learned and so on. The meeting was hosted by Grote/T.J. Dyer (aka Dyer), a Cincinnati-based mechanical firm.

After spending the morning discussing peer group business, Dyer took us on an afternoon site visit to see one of their projects, Mercy Hospital of Cincinnati. What was unique about the Mercy project was the fairly extensive use of prefab; it was very interesting to see its installation in the field.

As anyone who has designed and seen a hospital built knows, the most congested aspect of the job is usually the corridors. This is true not only from a design standpoint but also from a physical installation standpoint. Once the corridor walls are framed with studs, all of the trades need to travel down the corridors with their materials, tools and so on. This all has to happen while the trades are working overhead, often one on top of the other, getting all the duct, mechanical pipe, conduit, cable tray, water pipe, med gas and so on into the corridor ceiling. Then sheet rock has to be installed above the ceiling line for a one-hour rating, and all of the penetrations through that sheet rock have to be fire-rated and inspected. In seismic areas, the seismic bracing needs to be inspected as well. All the while, the trades are trying in vain to travel through the corridors. It’s a frustrating process on any hospital job, to say the least.

On the Mercy Cincinnati project, Dyer came up with a unique solution to this problem. They took the lead in designing a prefabricated corridor ceiling system that was built off-site and installed simply and quickly after being delivered to the site.

Dyer rented a nearby warehouse and created 40-foot lengths of corridor ceiling sections, using a tube steel frame to support the general construction as well as all of the utilities. The sides of the frame included the rated sheet-rock walls, and the base of the frame included the track for the corridor studs. The corridor ceiling space was completely finished in every respect. Pipes and ducts were insulated and labeled. Wall penetrations were fire-caulked. Each 40-foot length included fittings necessary to connect the lengths together once the sections were hoisted into place using screw jacks. Even curved corridor sections were prefabricated in straight lengths that were disguised above the corridor ceiling, hiding the fact that they weren’t actually smooth curves. The results were nothing short of remarkable in the time and money this execution saved the project. Plus, the tradesmen benefited greatly from being able to work on the ceiling components at table height in a comfortable warehouse rather than having to work overhead exposed to the summer heat.

When the ceiling modules were shipped to the jobsite they were stacked two-high, four per truck, and lifted by crane onto their respective floors. From there they were lifted and bolted into position, connected end to end, and branch stub-outs were connected to the patient room piping, ductwork and conduit.

In addition to the prefabricated corridor ceilings, the patient toilet rooms were prefabricated by PIVOTek, a sister company to Dyer. Toilet modules are built in PIVOTek’s fabrication shop, complete, ready to ship to the jobsite. All they require is field water and waste connections, power, ventilation and exhaust, as well as a sprinkler head. Everything else is included as part of the pod — walls, floor, ceiling, drain, tile, accessories and even toilet paper on the toilet roll.

In order for the module’s tile floor to lie flush with the structural slab, PIVOTek produces a form for the slab pour that creates the necessary concrete recess and has all of the necessary slab penetrations preset in the appropriate location. Once the slab is poured, the toilet module can be delivered to the jobsite and rolled into position with a pallet jack. The pod is left “under wraps” until it is time to complete the wall construction around the module to prevent damage from the elements and other construction-related hazards. Planning can be critical, since space above the module is limited by the floor-to-floor height of the project. Hospitals tend to be more generous with space and less access-critical, while hotels sometimes will have only a few spare inches above. In fact, if modular toilet construction is being considered for a project, it is important to make the decision early on, since the process can affect the layout of the toilet room and associated utilities.

Most of us have seen the YouTube videos of tall buildings being constructed in China in record time using extensive prefabrication. There is no doubt that prefabrication carries major benefits, but it is not without its challenges, especially in this country. The PIVOTek modules are not fabricated using union labor; this can be a real challenge to their application on location-specific projects, some unions being stronger and more restrictive than others. These union issues need to be addressed in advance in order to use the prefabrication process successfully.

Timothy Allinson is a senior professional engineer with Murray Co., Mechanical Contractors, in Long Beach, Calif. He holds a bsme from Tufts University and an mba from New York University. He is a professional engineer licensed in both mechanical and fire protection engineering in various states, and is a leed accredited professional. Allinson is a past-president of aspe, both the New York and Orange County Chapters. He can be reached at laguna_tim@yahoo.com.