The Indiana Hardwood Cross Laminated Timber project will explore the creation of a new value-added timber product by upcycling low-value hardwood sawn logs that are extracted from Hoosier National and INDR forests lands during salvage harvests. This low-value hardwood would be used to create hardwood Cross Laminated Timber (CLT), which can then be used as a primary structural material for mid- to high-rise buildings. Through material research and a built demonstration, this project will prove that a new timber market can be created in Indiana as well as the American Mid-west region, resulting in positive growth in rural manufacturing and forestry jobs, more responsible forest management practices, and a reduction in wildfire hazards.
Hardwood timber is the largest cash crop in Indiana with an average of 80 million cubic feet extracted annually over the last 25 years. However, over 50 percent of this material goes to producing low-value industrial products. This low-value resource represents an immense material supply that can be reassessed and optimized for higher-value use in the building material market in the form of CLT. The production and material properties of CLT effectively counter every reason that relegates this resource to be low-value in the current marketplace. By redirecting harvesting, processing, and production streams of this existing resource, a new timber product market can emerge. Hardwood CLT can offer superior structural capacity compared to traditional softwood CLT. Also, with rising global temperatures, softwoods are increasingly prone to threats by insect infestation and disease. By focusing on creating mixed hardwood species assembly CLT rather than the traditional single species CLT, a larger pool of material stock can be accessed, resulting in larger product yields as well as more diverse sylvicultural practices within Indiana forestlands.
Custom CLT layups, per APA PRG320 Section 7.2.1, would have similar strength properties (gravity in range .5-.6 and E-modulus around 1.7) and glue characteristics meeting species grouping and grading rules for hardwoods per AITC 119 listing Ash, Beech, Oak and Hickory in Group A and Maple in Groups B and D, which together account for nearly 60 percent of hardwood extracted from Indiana forest lands. The proposed assembles would explore the use of higher-grade lumber in the major strength direction (parallel lamellas) and lower quality lumber in the cores or minor strength direction (perpendicular lamellas). By changing the grade and species of wood, the layup of the individual component boards, and the type and approach of adhesive technologies, the project aims to optimize CLT products so that it can be used for a wider range of applications compared to traditional CLT.
In partnership with the Indiana Hardwood Lumberman’s Association as well as with officials from the Indiana National forests, the project will utilize specific native species that are within strength properties suitable for CLT as primary structure for large-scale buildings. The material will be processed in Indiana mills and transported to our fabrication partner Smartlam, where a series of mix-species assemblies will be laminated. The assemblies will then be brought to Clemson University’s Wood Utilization + Design Institute where, with the assistance of structural engineering partner Bensonwood, the structural qualities of the various assemblies will be evaluated. This will help determine layup configurations that have potential for commercial market applications and can be utilized for the Demonstration Project.
The Demonstration Project will be constructed in the city of Columbus, Indiana, where it will be displayed in the city’s main plaza during the 2017 Columbus Design Biennial, Exhibit Columbus. During the 3 to 6 month period of the Biennial, the hardwood CLT structure will be monitored and evaluated. The design of the Demonstration Project has already been approved for construction by Exhibit Columbus officials and the city. It will be prominently featured in numerous media outlets and publications, bringing significant attention to mass timber construction to a large public audience and educating elected officials, developers, engineering firms, and business in the benefits of using wood as a structural material in large buildings. At the completion of the Demonstration Project’s testing period, additional product testing will occur with the objective of PRG320 compliance and APA product approval in 2018.
The Indiana Hardwood Cross Laminated Timber Project aims to promote the use of Indiana hardwood as a viable and robust structural building material and to increase the demand and value of wood products already harvested from national forests within the state. This could also result in the expansion of specialty wood product markets such as wood composites, grade lumber, and framing/furniture manufacturing. In addition to benefiting local, state, and regional economies in the form of jobs and saleable products, this untapped opportunity to boost demand and value for national forestland products would provide significant revenue for the US Forest Service, allowing for continued forest restoration and management, which would in turn improve forest health, reduce fuels in wildland-urban interface zones, and improve wildlife habitats.