Development of fire-resistance laminated timber Moen-Wood(Three-hour fire-resistance)- Buildings can be made of wood with an unlimited number of floors

In development of columns and beams using fire-resistance laminated timber, Moen Wood^※1, Takenaka Corporation (President: Masato Sasaki) has obtained the Minister of Land, Infrastructure, Transport and Tourism's certification for fire-resistance structural members (three hours).
After previous development of Moen-Wood and obtaining certification from the same ministry for fire-resistance structural members (one hour and two hours), this product has been applied to 20 mid-to-high-rise hybrid timber buildings up to now. This began with a project that was completed in 2013. (Three projects were under construction as of the end of October.)

When making a building, the Building Standards Act specifies fire-resistance by the number of stories. Similarly, in the case of mid- to high-rise wooden hybrid buildings, the fire-resistance required for structural members varies depending on the number of stories in the building. It is possible to build a four-story building or four floors on top of a building if using one-hour fire-resistance Moen-Wood, and a 14-story building or 14 floors on top of a building if using two-hour fire-resistance wood.
With the development of three-hour fire-resistance Moen-Wood, a wooden structure can now be adopted for buildings of any number of stories, making it possible to convert buildings of 15 stories or more into wooden structures. This had not possible with the previous Moen-Wood.
Takenaka will continue to contribute to the realization of a decarbonized society by promoting wood and wood-based construction, and utilizing domestic wood through fire-resistance and mid-to-high-rise hybrid timber technologies.

As with the previous one- and two-hour fire-resistance "Moen-Wood," the three-hour version is also fire-resistance structural wooden members (laminated timber). These are comprised of three layers: a wooden "wood structure " a " fire stop layer " made of gypsum material and wood, and a wooden " wood finish layer (char layer)." Then these are used for columns and beams. In order to ensure fire-resistance performance, Takenaka has developed and commercialized a cross-sectional configuration that combines laminated timber and gypsum material for a fire stop layer. Moen-Wood ensures fire resistance performance by creating a situation whereby the outermost wood finish layer(char layer) burns slowly to suppress heat penetration, and the gypsum material in the second fire stop layer absorbs heat. Then the wood structure will not exceed a combustion and carbonization temperature of 260°C.

To obtain ministerial certification for fire-resistance structural members with wooden materials, it is necessary to pass a performance evaluation test by a public testing facility. A sample is heated in a refractory test furnace for three hours while a load is applied to the wood structure, and after completion, it is cooled inside the same furnace. The fire-resistance coating layer of the member must completely stop burning by itself within 24 hours, and the wood structure of the structure must be undamaged and uncarbonized. In the case of three-hour fire resistance, the inside of the refractory test furnace rises to 1,110°C, and it is necessary to ensure fire resistance performance for a temperature that significantly exceeds 260°C, at which the wood burns and carbonizes. As a result, it has been proven that the fire-resistance performance is equivalent to that of reinforced concrete and steel-frame fire-resistance members.