This is the second of a 3 Post series on using prefabricated systems in design and construction. This Post explores one of the most significant areas of productivity improvement in the design and construction of complex structures–the use of multi-discipline, multi-trade prefabrication.
In Post 1, we discussed the design and installation of a Variable Refrigerant Flow (VRF) heating and cooling system. That system was manufactured by a single Company, Mitsubishi. It was also (essentially) designed by Mitsubishi and the local installation was done by competent, regional, Mechanical system subcontractors, M-Tech and Heating & Plumbing Engineers (HPE) with support from a local Electrical Subcontractor. In fact, most projects, today include a number of similar systems that are pre-fabricated off site and then installed at the project. The majority of the examples are in the single trades of Mechanical, Electrical and Structural subcontracting. The use of single trade pre-fabrication is now accepted as an integral part of those subcontractors’ business, and we should expect to see it used much more often.
The major productivity gain in design and construction in the future may be in the use of multi-trade/ multi-discipline pre-fabrication for complex systems. Essentially this is the bringing together of several different trades and contractors or subcontractors in a fabrication/ manufacturing environment. In that space they work together building any number of complete assemblies such as a patient room headwall system. The key is the work environment can include all disciplines working at the same time on a single, repeating building assembly.
Multi-trade, multi-discipline prefabrication brings a number of key benefits to project:
1- The potential for schedule improvement can be significant as the trades, working together, can work in parallel and pull work forward to reduce peak manpower required on site.
2- The quality control for the finished product is substantially better and more consistent than field assembly. Rework or repair is also reduced dramatically. For example the finished assembly can be viewed from 360 degrees i.e. on all sides, to identify constructability issues very early. Early decisions can be a concern for owners and the design team, but the benefit of those early decisions is optimization of the project and work flow. That is not typically possible when work is done only on a project site;
3- Early design of systems must be completed with the client and all team members in agreement. That requires earlier decision making on everyone’s part. Proto-typing and mock-ups can be used cost-effectively to speed that decision-making process.
4- The systems are being built in a much safer environment. The trades are not working on ladders or in restricted spaces, and the work space more closely resembles a manufacturing environment which reduces work site congestion.
5- Materials can be sourced world-wide, which limits the need to sole-source or to “settle” for parts and materials that are only available locally;
6- There may be financial benefits for the client in terms of materials used and accelerated depreciation- and those decisions are made on a case-by-case basis.
7- Construction waste is minimized because procured materials are pre-cut to specific lengths, widths and heights which is consistent with LEED and LEAN construction practices.
There are many examples of the use of multi-trade pre-fabrication and it seems to be more accepted—in fact encouraged- internationally. One good example, locally, is at the University of Colorado Hospital, where the team of HDR Architects, Haselden Construction, Encore Electric and U.S. Engineering developed a plan for prefabricating the patient room headwalls—which typically are consistent across all of the hospital rooms. They also developed a plan to prefabricate all of the utility routing in the corridor ceilings. The Haselden Construction website carries a video that provides highlights on how those two systems came together and were installed in each patient rooms and in the corridors. The hospital opened some four months early through, in large part, to the use of the multi-trade prefabrication systems. The hospital also opened with a cost savings over the traditional fabrication process. That video can be found at;
In discussions with the team members, the installation process provided a number of benefits to the Hospital (UCH). First, UCH had early delivery of more hospital beds; second, for the subcontractors and supplier firms that were involved in the development as they saved significant time in production; and third, for the design team as the design was completed earlier thru mockups and virtual environments which resulted in fewer field changes.
The Take-Away—What Made the Process a Success at University of Colorado Hospital?
There were a number of steps taken that made the use of the multi-trade prefabrications process a success. While every project is unique, for the University of Colorado Hospital the following steps made the difference.
1- The construction and Mechanical/ Electrical/ Plumbing (MEP) teams were selected early and managed collaboratively. Rather than use the traditional project hierarchy in the design and in the field, the team structure was flattened. Decisions were driven by the patient need and implemented with all team members “at the table”—including the owner.
2- The client was engaged early to make decisions. Specifically the team built a mock-up of the headwall units and had moveable components (attached by Velcro) that the professional staff of Nurses and Doctors could review and discuss. Team members could move components easily as they judged which arrangement of outlets, alarms and gas connections would be best. The result was a headwall that had buy-in very early from all team members, and that could go into early production. That included early material purchase and fabrication.
3- The corridor ceiling piping assemblies could also be viewed by the Hospital staff, including hospital engineering. Those assemblies also had early design input from the entire team and included an allowance for future piping installations. Again, with early approval, materials could be purchased early and the entire assembly was fabricated off-site in the protected environment.
4- One interesting benefit of having the corridor ceiling utilities prefabricated was that the corridors were open for all trades to walk thru during construction, except when a prefabricated unit was being put into place. That removed the typical corridor clutter of ladders and people and made material movement through that corridor much faster throughout the project schedule.
5- All system inspections of the headwalls and corridor piping by the client and other inspectors could occur off-site, in a well-lighted and protected environments. The inspections could also be 360 degree as noted earlier.
6- The need for skilled trades on site was reduced dramatically and a majority of the skilled trade work was completed in a manufacturing environment. That increased craft productivity and improved the resultant quality of the work. It also reduced construction activity adjacent to an operating medical facility.
7- There was limited re-work required on-site after installation. Problems were found during the prefabrication and repaired prior to the assembly being on site.
8- The insurance policy on site was an OCIP or Owner Controlled Insurance Policy—see also;
The terms of that policy were coordinated with the actual flow of the materials and work to ensure the owner was protected at each step- from assembly- to transport- to installation. The system and components were always insured.
9- Because the majority of the work could proceed in a safer work environment and at a pace that could be disengaged (to a large degree) from the on-site work, the client needed to work with the team in modifying the payment schedules to accommodate this offsite work. In many ways, the prefabricated components needed to be treated more as a manufactured assembly (which they were). The client understood the difference and was able and willing to make the adjustments.
10- The Contractor had to manage the tax implications of manufacturing components in an off-site location, and then moving them to the project site. Each local jurisdiction that was impacted needed to understand how the taxes would flow. As University of Colorado Hospital is a Colorado non-profit, that process was simplified. None-the-less the analysis had to be completed and accepted by each Jurisdiction.
In net—the project was completed 4 months early and at an advantageous price to UCH. The Hospital was able to serve a much larger patient base, sooner, and the design and construction process flow was improved as was quality control for the pre-fabricated systems. The UCH project is a good example of the construction processes all project sites will be using in the future, especially those projects that include a repeatable, complex, element such as a headwall or piping within the corridor ceilings. It also shows the exceptional promise of multi-trade, multi-discipline prefabrication in improving the delivery of complex assemblies and buildings.