Out-of-grade sawn pine: A state-of-the-art review on challenges and new opportunities in cross laminated timber (CLT)

Plantation softwood is the future timber material resource for building and construction. However, significant volumes of sawn softwood are considered out-of-grade and sold at a loss. New approaches and methods need to be implemented to value-add out-of-grade timber and increase structural yield from existing plantations. This paper provides a critical review of out-of-grade characteristics of pine timber to gain an understanding of the strengths and weaknesses of this resource as a structural building material. Methods to incorporate out-of-grade timber into current building systems are presented and building technologies that can facilitate this use are identified. Finally, it discusses developments and important considerations for design of cross laminated timber (CLT) as a prime example of a building system with good capacity to incorporate high volumes of out-of-grade timber. This provides critical information for the maximum utilisation of sawn out-of-grade pine and is anticipated to create new opportunities that can effectively incorporate this renewable and sustainable material resource into innovative building systems and technologies. (C) 2019 Elsevier Ltd. All rights reserved.