Wood-strand sandwich panels for panelized construction

Abstract

Changing resources and demand for reduced energy dependency have led to consideration of combining energy and structural performance codes for construction of sustainable buildings with low embodied energy materials and reduced operational energy (residential and commercial buildings account for almost 39% of the total U.S. energy consumption and 38% of U.S. carbon dioxide emissions). Washington State University has developed a wood-strand sandwich panel with a thin walled 3-D core that shows promise for use in building envelopes. This lightweight sandwich construction with a thin-walled 3-D core creates a structural panel using undervalued timber from forest thinning or fast growing plantations. Research is focused on replacing typical construction products such as oriented strand board (OSB) as sheathing with the possibility of creating a thicker built-up panel geared toward panelized construction similar to cross-laminated timber (CLT) and structural insulated panels (SIPs). Small-diameter ponderosa pine woodstrands were utilized in manufacturing of a sandwich panel that has a bending stiffness that is 21% stiffer than commercial OSB, but a density of approximately 300 kg/m3. The desirable mechanical and thermal results allow for this material to be utilized in designing panelized wall, floor, and roof elements for countless building construction applications. Compared to currently used OSB, which represents over 60% of the sheathing market, the thicker lightweight sandwich panel is significantly stiffer in bending with increased R-value while utilizing over 40% less material than OSB of equal thickness. Resin consumption, which accounts for approximately 30% of the production costs in a typical composite panel plant, is reduced by over 40%. Incorporation of foam insulation into the cavities of the sandwich panel further increases its flexural stiffness and thermal properties. This presentation will focus on manufacturing, mechanical and thermal properties, and application of wood-strand sandwich panels.