Examination of manufacturing conditions of cross laminated timber made with karamatsu (Larix kaempferi) or todomatsu (Abies sachalinensis) for visible use under low humidity
2020
Ishihara, W. (Hokkaido Research Organization, Forest Products Research Institute (Japan)) | Miyazaki, J. | Ohashi, Y. | Nakamura, K. | Takanashi, R.
Cross laminated timber (CLT) has dimensional stability because the grain direction of consecutive layers is oriented orthogonally. However, gaps at the edge joint and checks easily occur on the visible interior surface of used CLT because the indoor environment in northern Japan is generally low in humidity during winters. In this study, we monitored the surface appearance of small CLT specimens, made with Karamatsu (Larix kaempferi) or Todomatsu (Abies sachalinensis), under low-humidity conditions. As a result of this study, we recommend specific manufacturing methods for CLT for visible use in interiors as follows : 1) The moisture content of laminae should be lower than the standard moisture content of the structural timber, with a recommended moisture content of approximately 8%-9%. 2) Edge-gluing in interfaces between surface laminae should be used to limit the occurrence of gaps at the edge joint between laminae. 3) Use of the pith side of adjacent surface laminae facing up should restrict the occurrence of checks on lamina surfaces.
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