Building Code to Allow Visually Exposed Wood Structures in Midrise
Under the current Japanese building code (Building Standard Law: BSL), fire resistive structures are required in all midrise buildings (exceeding 16 m in height or 4 storeys or more). The common method of making wooden structures fire resistive is to clad them with gypsum board. However, there have been discontent to this requirement among designers claiming that the occupants cannot visually appreciate wooden materials in such structures. To address this issue and encourage further wood use, MLIT (Ministry of Land, Infrastructure, Transport and Tourism) recently announced that they are amending the BSL so that quasi fire resistive structures can be used in midrise buildings. Quasi fire resistive structures are achievable by char margin design (sacrificial layer approach) for large wooden members that are visible. With this amendment, it is anticipated that building occupants will be able to see exposed wooden structural members are used in such midrise buildings – leading to proper promoting opportunities for wooden building products sector.