Siding board for clapboard boarding and a clapboard boarding structure

摘要

Siding boards for clapboard boarding are used in a clapboard boarding structure in which lower side portions of upper siding boards are overlapped frontward of upper side portions of lower siding boards for installing a plurality of siding boards to a framework of a building. The siding boards are ceramic type siding boards with vertical joint grooves being formed on designed surfaces. Lower edges of the lower side portions of the siding boards are formed at different heights with the boundaries of the vertical joint grooves. Rear surface stepped portions that have been obtained by notching the rear surface are formed at the lower side portions. Upper end portions of the rear surface stepped portions are formed in a substantially straight line in lateral directions.