Kumagai Gumi Co.,Ltd. obtained 2-hour fire-resistance certification from the Minister of Land, Infrastructure, Transport and Tourism for CFT columns using “Dress Wood®,” a steel structural member with timber fire-resistant cladding. The certification was obtained for technology jointly developed with ホルツストラ.
Kumagai Gumi Co.,Ltd. applied “Dress Wood®,” a steel structural member using timber as fire-resistant cladding, to CFT columns and obtained 2-hour fire-resistance certification from the Minister of Land, Infrastructure, Transport and Tourism. This enables the technology to be used from the top floor down to the 14th floor of a building. Combined with existing fire-resistance certifications for columns and beams, it is expected to expand the options for mid- and high-rise timber buildings.
A feature of this construction method is that the timber thickness of Dress Wood CFT columns is at least 30 mm, while the net covering thickness, including insulation, is at least 60 mm. This is equivalent to the thickness used for 1.5-hour fire resistance and achieves a slimmer finish than the conventional configuration with a sprayed rock-wool substrate. Flame-retardant treated timber can also be used as the surface finish, allowing the method to accommodate interior-design restrictions.
Going forward, the company plans to actively promote the use of Dress Wood in actual projects and develop structural members suited to various fire-resistance requirements. Through wider use of timber and advances in fire-resistance technology, it aims to help realize a sustainable society.