Field Tests of naturally Durable North American Wood Species

IRG/WP 08-10675

P E Laks, P I Morris, G M Larkin, J K Ingram

There has been little field test performance data published on North American naturally durable species in general, and no published data on second growth material in particular. Yellow cedar (Callitropsis nootkatensis), western red cedar (Thuja plicata), eastern white cedar (Thuja occidentalis), and three wood species reputed to be moderately durable were installed in ground-contact (stakes) and above-ground (decking) field tests at test sites in British Columbia and Ontario, Canada and Florida and Hawaii, USA between the Fall of 2004 and Spring 2005. Where possible old growth and second growth material, with and without sapwood, were obtained and used in the testing. Results from ground-contact field stakes and above-ground mini-decks after 3 years exposure are presented. The test site with the fastest ground-contact decay rate was Florida. The fastest above-ground decay rate was seen in Hawaii. In general, yellow cedar was the most decay resistant, followed by the other two cedar species, then the three other species. There was no appreciable difference in decay resistance between heartwood samples from old-growth and second-growth western red cedar, yellow cedar, and larch (Larix occidentalis).

Keywords: naturally-durable, cedar, larch, tamarack, Douglas-fir, decay

Conference: 08-11-30/12-02 Flamingo Beach, Costa Rica

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