It’s been five years since I last wrote on prefabrication of exterior wall assemblies, and much has changed in the construction environment since 2011. A sputtering economy has markedly improved (though at a snail’s pace), and the focus of building activity has shifted from government work and renovations to certain target industries, such as insurance, energy and health care. Research and development in the material markets over the past five years have contributed such innovations as lightweight drywall and steel framing configurations that allow thinner gauges of metal to meet higher deflection standards (read: equivalent, or “EQ” studs). In addition, the ensuing years since 2011 have seen a rising demand for skilled manpower to satisfy the increased activity—a demand that is not being met for various reasons.
Similarly, the nature of prefabrication in the commercial drywall business has changed—or conformed, I should say, to the conditions noted above. In 2011, the vast majority of drywall prefabrication resided with the panelization of exterior skin—particularly with multistory designs incorporating EIFS finishes. The concept lent itself well to the repetition in design, the labor intensity of a multiple-phase finish and the relative light weight of the finished skin. With these conditions present, a panelized exterior still makes good sense. Framing, sheathing and EIFS are all preassembled ahead of time in a controlled environment. Onsite installation requires a fraction of the time.
But today panelization need not be limited to exterior skin. It seems that the changes in the construction environment cited above have given rise to the realization of another prefab concept: The panelization of interior partitions or, as I like to call it, assembly-line drywall. The concept is fairly simple. Shop drawings are rendered from the architectural plans and field-verified. Framing is performed in a controlled plant environment per the shop drawings on jig tables with components that are pre-cut by the manufacturer. Panels requiring plumbing and electrical are roughed in at the plant, as is the installation of drywall to one side. One-sided panels are shipped to the site in a sequence that enhances ease of installation and conformance to the job schedule. After a quick installation, electrical and plumbing are hooked up and inspected, the second side of drywall is applied, and all is ready for tape and finish.
Prefabrication of interior panels can conform to a number of scenarios, but there are several factors that optimize the concept’s application. A “through-ceiling” wall type is the most desirable condition regarding height tolerances. Three-piece “knock-down” type door frames that install after drywall are preferred for obvious reasons. A near-perfect flat concrete floor is a must to eliminate cocked racking of rigidly square panels, which would result in gapping at the joints.
The recent boom in office buildouts and medical office buildings has improved the feasibility of the interior prefab concept (read: through-ceiling wall types and knock-down frames typical of office work), while the development of lighter-weight materials has enhanced its advancement, as a 10-foot by 9-foot finished panel can be manually handled by two unskilled laborers without the need of a forklift or crane.
One advantage to prefabrication is the boost the controlled environment lends to productivity. In the plant, a two-man framing crew can assemble upward of 360 linear feet of partition per day, and one hanger with a laborer can hang an average of 3,000 square feet of board a day. On site, a four-man installation crew can set and brace 480 linear feet of wall per day. These impressive bumps in productivity are enough to offset transport costs (depending on distance), shop drawings and plant costs. The greatest advantage, though, to the extraordinary rise in productivity provided by panelization lies in the reduced demand for manpower in an environment that is severely limited in that resource.
Perhaps the strongest attraction to the prefab concept comes with the limited amount of time and reduced head count required on the site. Schedules require shorter durations for several scopes. And while the one-sided operation precludes taping in the plant, smart sequencing can allow that one side of drywall to occur on all four walls of an office, thus enabling the tape and finish of every other office as soon as panels are set and braced—another time-saver. Less time and attendance on site translates into other advantages: greater safety, less liability, less crowding with other trades, and less scrap generated on site. These added benefits are occurring to general contractors and owners who are likely to persuade designers to incorporate optimum conditions for interior panelization into their designs.
Prefabrication can be a boon to commercial drywall bidmeisters in several respects. The controlled environment of the plant allows for predictable labor productivities. Components pre-cut to size minimize the waste factor, and a drop-off delivery of material to the plant eliminates a stocking fee, thus labor and material are both positively affected for the estimate. But as owners, architects and general contractors come to recognize the time savings that goes with prefabrication, the estimator who can offer this alternative may well have the edge over others.
Vince Bailey is an estimator/project manager working in the Phoenix area.
