Field Performance of Thermally Modified Wood in a Severe Test Site

Abstract

Thermally modified wood (TMW) is a growing trend in North America in areas of low decay and insect pressure. Thermal modification improves dimensional stability, decreases moisture uptake, and results in a darkened color that resembles tropical hardwoods. More testing is needed in severe decay situations and in areas of high termite pressure to fully understand the boundaries of its material performance. Within the AWPA, the P9 subcommittee (non-biocidal wood protectants) has been working to develop test methodologies and appropriate use category designations for TMW materials. The Forest Products Laboratory has been conducting field tests at a severe decay hazard site (Saucier, Mississippi) since 2013 to evaluate the performance of several wood species with varying degrees of thermal modification and additional surface coatings aimed to increase product longevity. Results to date show that in instances of close ground proximity, almost all the thermally modified samples have failed unless they were subject to a supplementary coating or treatment. In accelerated field testing of these materials, it has been observed that sample size has shown to be an important parameter and careful attention needs to be paid when preparing future field tests to properly evaluate TMW. Five- and ten-year results of separate ongoing field tests are reported along with a preliminary discussion of findings and steps forward.

Citation

Kirker, Grant; Mankowski, Mark; Aro, Matt. 2023. Field Performance of Thermally Modified Wood in a Severe Test Site. In: McCown, C., ed. Proceedings One Hundred Nineteenth Annual Meeting of the American Wood Protection Association. Tucson, Arizona. April 3-5, 2023. Birmingham, AL: AWPA: 141-148.