When constructing a mid-to-high-rise building more than 4 stories in general in Japan, it is necessary to have a fireproof structure stipulated by the Building Standard Law. The performance required as a fireproof structure in Japan is generally stricter than in other countries, and it is required to be structurally sound after a fire even without fire extinguishing activities. In order to satisfy this requirement, the structural member must continue to support the load during the event of a fire. In the case of wooden structure, this means that the combustion should be eliminated spontaneously, and the charring of load support portion is not allowed. Under these conditions, many wooden fireproof structures have already been developed, and wooden buildings are actually being constructed widely. The method of making a wooden fireproof structure is roughly divided into (1) a “inorganic covering type” with gypsum board and (2) a “flame die out type” using fire-retardant treated wood or heat absorbing material. In this report, we will introduce these wood-based fireproof structures, as well as the fireproof structure of “flame die out type” developed by our research group, and the cases where the wooden fireproof structure has been actually applied to various buildings.

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