Clemson’s Innovative Construction Method Offers Solution for Rapid, Low-Tech Sustainable Housing

Forget baseball and apple pie. As an architect, there is little else more American to me than wood-framed houses. A 2017 national housing census reported 92% of new single-family homes are framed with wood. This is hardly surprising, as light framing with dimension lumber has been the dominant method in the U.S. ever since the advent of industrial sawmills. It is accessible, economical and ingrained in our thinking. Wood building materials also offer unrivaled environmental benefits, owing to their natural insulating qualities, renewability, low embodied energy, and inherent sequestration of carbon from the atmosphere.

Light framing has always capitalized on standardized building elements, from lumber to engineered joists and from sheathing to fasteners. Now, new production technologies are opening the door to increasing measures of prefabrication. I recently had the chance to visit a remarkable wall and roof panel factory in New England, and was able to see firsthand the speed and accuracy of automation, along with the efficiency and safety of off-site construction.

Since 2014, I have been working with faculty colleagues and students in the Clemson University School of Architecture to leverage advanced manufacturing technologies toward a different form of prefabrication with light wood components, one that retains the precision and coordination of factory production, but with all of the nimbleness of on-site construction with lightweight, easy-to-handle pieces. First developed in conjunction with our participation in the Department of Energy’s 2015 Solar Decathlon Competition, our patented system utilizes prefabricated building components cut from plywood sheets by computer numerical controlled (CNC) routers or water jet cutters. We call the system Sim[PLY].

The walls, roofs and floors in a Sim[PLY] structure are composed of built-up studs (at 24” on-center), joists and rafters, each consisting of plywood web and flange members. All of the framing pieces are designed to interlock with each other using a variety of different joints developed for the system, from tab and slot joints connecting perpendicular members, to scarf-type joints connecting members in the same plane. There are joints designed to lock walls in place once standing (reducing the need for temporary bracing), and other joints designed to resist uplift. All of the elements are pre-measured and pre-cut, and, in lieu of nails, stainless steel cable ties are used to fasten the pieces together. This all makes Sim[PLY] construction quieter, safer and free of on-site power demands. Moreover, the components are able to be disassembled and reused, just as easily as they are assembled in the first place.

Another intriguing benefit to this kit-of-parts approach is the ease with which components can be customized for optimal performance and coordination. Imagine the insulating capacity of thermally broken, double stud walls but with reduced complexity. Imagine studs that are pre-routed and labeled for the passage of electrical wiring and plumbing pipes. This is just a small sample of what is possible with this way of building.

Using the Sim[PLY] system, Clemson’s Indigo Pine House was constructed, wired, plumbed and furnished in nine days for the 2015 Solar Decathlon – all by a team of students and faculty. This followed much prototyping as well as rigorous structural testing and verification that the frame could meet the seismic requirements of the southern California competition setting (seismic category D2). This same testing likewise proved that Sim[PLY] shear walls are suitable for the hurricane force winds of coastal North and South Carolina (up to 135 mph).

In addition to the Indigo Pine House and the full-scale prototype house that preceded it, the Sim[PLY] system has been used to build a commercial kitchen structure in Greenville, S.C., a community arts pavilion in Summerton, S.C., and an orchestra shell in Genoa, Italy, among other projects. Most recently, we’ve partnered with the Anomura Housing Society in Victoria, British Columbia, to study the application of Sim[PLY] to affordable housing in that city and the surrounding areas. Faced with escalating land and labor costs, plus high seismic demands and British Columbia’s stepped energy codes, Anomura is turning to Sim[PLY] for its structural and thermal capabilities, its ease of assembly, disassembly and reuse, and its community-building, participatory nature.

Closer to home, and through the support of Clemson’s Wood Utilization + Design Institute and the USDA Forest Products laboratory, we are studying the application of Sim[PLY] to disaster relief structures. The Congressional Budget Office estimates that 1.2 million Americans live in locations at risk of substantial hurricane damage. This office also estimates that hurricane damages cost government around $28 billion per year, and that this number will rise from the effects of climate change. Working alongside Atlanta-based partners from Perkins + Will, a global architecture firm, our colleagues in Clemson’s Industrial Engineering program recently developed a logistics model aimed at predicting advantageous locations for pre-hurricane material storage and post-event distribution. The next phase of the research will involve the design of emergency medical clinics and housing, using prefabricated systems, as test cases for the logistics model. Sim[PLY] is one of the systems with which we’ll be working. It has the advantage of being easily deployable, and rapidly assembled without power tools.

We are deeply interested in where this research will take us with the Sim[PLY] building system. We are also excited about the potential for other future partnerships with fabricators and building professionals to provide critical feedback and lead to system advancements.

If you are interested to learn more about our work with Sim[PLY], write to us simPLY@clemson.edu.

Main photo: Professors Dan Harding and Dustin Albright have been constructing a prototype house in Pendleton, South Carolina, using the new Sim[PLY] building system, a patented technology that allows a home to be built without the use of power tools or nails.

Photo 1: The Sim[PLY] building technique debuted in 2015 at the U.S. Department of Energy’s Solar Decathlon. With this technology method, off-the-shelf plywood is cut by CNC routers into interlocking tab-and-slot pieces that fit together to form a solid, tight frame. Digitally cut files can be emailed to a CNC fabricator and then shipped flat-packed to the construction site, ready to be assembled by hand.

Photo 2: Sim[PLY]’s innovation doesn’t mean compromising on design. The interior of Sim[PLY] structures can be finished to meet an individual’s personal preference, whether it’s rustic wooden floors or classic ceramic tiles. Image Credit: Thomas Kelsey/U.S. Department of Energy Solar Decathlon