Cladding boards in wooden facades: Selection of wood species, cutting direction, thickness

Weathering of wooden cladding is caused mainly by solar radiation and moisture. Moisture changes causes stresses in the cladding boards that leads to warping and cracking. The aim of this study is to investigate the possibility to reduce the amount of warping and cracking of the cladding board by the selection of wood species, cutting direction and thickness of the board. The selected variables were radial cut spruce, tangential cut spruce and glued spruce, pine sapwood and pine heartwood, and board thicknesses 23 mm, 28 mm and 38 mm. The investigation was performed by a two-step test: cracking test and dimensional stability test. Both tests showed that cutting the cladding boards in the radial direction instead of tangential direction, increasing the thickness of the board and avoiding pine sapwood can reduce the amount of cracking and warping in cladding boards.