A market of preserved wood products in Japan has two unique histories. First is the market shift to residential ground sills from utility poles and sleepers; the other is the stop of CCA treatment caused by the new effluent standard. In 2018, around 85% of preserved wood products used for residential ground sills were treated with non-CCA such as Cu-based agents. Since the market of treated wood has been so low in Japan, various types of durability evaluation methods were not needed. The in-ground field test is the only standard test in Japan. On the other hand, the exterior use of wood above ground, such as decks and cladding, is expected as a new market of treated wood. As above-ground conditions are different from in-ground, a lot of field tests for the above-ground has been conducted throughout the world. A new field test is also needed in Japan to evaluate the durability of wood products. This paper reports on the current status of durability standards in Japan, and the recent studies and future developments of durability assessment for above-ground use in Japan.

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