Written by Jack McManus – Sold in standard 4 foot wide sheets since 1928, plywood has been a staple of conventional construction for nearly a century. Dimensionally strong, easily cut, lightweight and capable of creating an effective barrier, plywood and other engineered panels like OSB, particle board, and MDF is ubiquitous, particularly for their use as sheathing material in balloon and timber frame construction systems. Boats, airplanes and even automobile frames have historically been built out of plywood, predating (or replacing) steel, aluminum, and fiberglass. As a simple material capable of being manipulated and shaped in a wide variety of ways, sheet ply was also favored in furniture and architectural designs by modernists including Charles and Ray Eames, Eero Saarinen, Alvar Aalto, and Marcel Breuer.
Woodworking techniques based on adhering together thin lams of lumber have been traced back to Ancient Egypt, but modern plywood sheets have only been feasible since the mid-1800s when Immanuel Nobel (the father of dynamite inventor and prize namesake Alfred Nobel) invented the rotary lathe. This milling tool processed raw timber into raw material for plywood by peeling entire logs into thin sheets of veneer (similar to a roll of toilet paper being pulled from its cardboard tube). To this day, plywood is produced by stacking layers of veneer, gluing them together, and then joining them in a press, with the grain orientation of each layer rotated 90 degrees to the layer below or above it for uniform strength across each dimension of the sheet. Other engineered sheets are made with wood particles of various size and orientation, rather than sheets of veneer, but are similarly glued and pressed together.
Today, engineered wood sheets are used in construction at every scale, but the material has also developed a stigma as a visual symbol of urban blight. It is commonly used to seal up broken windows and doors of abandoned houses; a practice that has been problematized on the basis of aesthetics and crime prevention. FEMA now recommends clear plastic sheeting be used instead, and the state of Ohio and city of Phoenix, Arizona have even banned the use of plywood to board up vacant buildings. However, modern design technologies have created a new future for plywood as an architectural material, and designers are suddenly discovering exciting new ways to build plywood structures.
For most of the history of its use, plywood has commonly been deployed as whole sheets or cut into still-rectangular partial sheets with a panel saw, table saw, or circular saw. However, with the relatively recent invention of CNC routing and similar computerized cutting methods, it has become possible to repetitively carve sheets of engineered wood into tightly controlled, geometrically perfect shapes with a precision that cutting by hand could never match. This has opened a world of new ways to use wood sheets in projects, creating possibilities for turning the flat material into three-dimensional forms by stacking sheets as parallel planes or stitching them together. CNC routers can also turn wood sheeting into perforated or pierced screens cut with carefully-designed patterns, and designers have found that strategic cuts or kerfs can allow sheets to bend and twist in stable and controlled ways to create sculpted forms, and the convenience of sharing CAD files enables open-source building concepts like WikiHouse.
The CNC routing is also vital to the production of Cross-Laminated Timber. These thick panels molded together from boards of solid lumber rather than plywood’s thin veneers promise the load-bearing capabilities of reinforced concrete while retaining the sustainability benefits of natural timber. While CLT, wood-plastic hybrids, and the promise of revolutionary new products like transparent wood may look like the future of construction materials, these projects show how creative design approaches and inventive uses of modern technology have established engineered wood sheets as a vital material of the present.