Defining the Next Chapter for Thermally Modified Wood

Thermally modified wood has a low environmental impact and favorable properties, such as enhanced dimensional stability, increased resistance to decay, and often aesthetically desired darker color (through-stained). Yet the lack of uniformity in production methods can cause substantial variations in quality. The industry lacks shared definitions, test methods, and verification pathways – gaps that ultimately hold back wider adaptation. For architects, builders, designers, and consumers, it is essential that thermally modified wood consistently meets high-quality standards. Therefore, stakeholders in the wood industry should investigate what a standard, certifiable framework might look like. The following section examines why standardization has become increasingly important.

The Case for Standardizing Thermally Modified Wood

In the construction industry and architectural sectors, the sustainability and durability of materials have been a focal point for many and a growing trend for years. This shift in priorities across industries has moved away from scarce raw materials such as exotic wood species, with experts looking into alternative options.

Rooted in trust, quality, and consistency, the hardwood lumber industry has long thrived on these strengths while adapting to the challenges posed by global demand and regulatory pressures. While buyers, builders, and other experts can rely on finding quality raw materials, they have faced a somewhat fragmented and inconsistent landscape for thermally modified wood. Customers need standardized classification systems, consistent test methods, and clear quality benchmarks that foster transparency and expand product knowledge to compare options effectively.

Jartek’s Commitment to Process-Based Certification

Designing thermal modification chambers has always been a highly customized process at Jartek, where each customer’s needs are met and the chamber is planned accordingly. Our process control technologies allow operators to monitor several process parameters like temperature, moisture, and time at each stage of the modification cycle. Creating such data points indicates that the process has been prepared for certification, as defining and controlling variables enable comparison and help ensure consistent performance.

In the thermal modification process, variation between different wood species, thickness of the boards, and their initial moisture content play a key role in the outcome. A process-based standard that focuses not only on final product performance - such as dimensional stability and decay resistance - but also on how the wood is stacked, loaded, and processed - is something Jartek advocates for.

Convincing buyers requires that they know and understand precisely what they are getting and feel confident specifying thermally modified wood in large-scale projects and international supply chains. Achieving process-based certification is not about limiting creativity but instead unlocking the scalability of wood thermal modification and creating trust among buyers and industry experts alike.

Partnering with NHLA: Paving the Way to a Sustainable, Standardized Future

NHLA represents uniformity in the hardwood lumber industry and is committed to education and quality assurance. In the thermal modification of wood, consistency signals quality—and it’s achieved by precisely controlling process parameters from start to finish. Existing grading frameworks supported by NHLA create an opportunity to standardize inputs and, as a result, achieve more predictable and repeatable outcomes.

Jartek’s global market experience, combined with the success of the NHLA grading system, shows that when producers align around consistent standards, it leads to greater market confidence, improved pricing, and stronger international recognition. By working with NHLA and other partners, Jartek aims to support a framework that reflects the lifecycle of the product and its environmental and human impact. Jartek seeks to build a framework in partnership with NHLA to reflect broader building market demands and bring much-needed clarity to wood thermal modification processes.

By Jartek