Fire-resistant wooden structure
Fire-resistant wooden structure is currently in the spotlight
【① Utilization of domestic timber is encouraged in Japan】
【② It is now possible to build fire-resistant wooden buildings]】
【③ More and more fire-resistant wooden buildings are built over the years】
||Standardization of performance by the amendment of the Building Standards Act
→ It becomes possible for fire-resistant buildings to be constructed with wooden materials
||The Japan 2x4 Home Builders Association acquires certification for fire-resistant construction
||The Japan Wooden Housing Industry Association acquires certification for fire-resistant construction
||The Act on the Promotion of the Utilization of Wood in Public Buildings becomes effective
→ In principle, all low-rise public buildings should be made of wood
||Yoshino Gypsum acquires certification for “Tiger Moen EX-B1” together with Nichiha
||Yoshino Gypsum acquires certification for “Exterior wall for fire resistant system with Duracrete finish”
||First regulatory notice concerning fire-resistant wooden construction (starting with MLIT Public Notice No. 861)
→ Exterior wall and partition wall for fire-resistant wooden structure using gypsum board are now stipulated in the regulatory notice
||Yoshino Gypsum acquires certification for “Tiger Moen EX-B2” together with Nichiha
The state of issuance of approval for the usage of Minister Certified Specifications for fire-resistant wooden building (Cumulative number from 2 Associations)
Based on documentations from the Japan 2x4 Home Builders Association and the Japan Wooden Housing Industry Association. Current data as of end of March 2017
【④ Fire-resistant wooden structure is made possible by using fire-resistant gypsum boards as cladding】
Fire-resistant buildings are required to have the ability to keep standing without breaking down even after the fire has extinguished, which is achieved by making the main structure a fire-resistant structure.
木As for fire-resistant wooden buildings, the wooden structure can usually be protected from fire by cladding the wooden structure with fire-resistant gypsum boards.*
*In case of fire-resistant wooden structure with cladding
6 advantages of fire-resistant wooden structure
【① Suitable for cramped small land plots】
By making the building as a fire-resistant wooden structure, it is possible for the construction to be done without using heavy equipment such as a large crane because its materials are lighter than other construction methods such as reinforced concrete structure or steel structure.
It can be flexibly adapted to flag lots and cramped small lands that can be obtained relatively inexpensively.
【② Excellent thermal insulation performance】
〈Comparison of overall heat transfer coefficient (heat transferablility)〉
【Reinforced concrete wall at 180mm thick + on-site polyurethane foaming at 35mm thick】
Overall heat transfer coefficient
【Wooden stick-framing construction (regulatory notice compliant specification) high performance glass wool 24k】
U=0.306 （in case of 2×6）
to 0.411 （in case of 2×4）
The inflow and outflow of heat at the exterior wall is
〈reduced by approx. 40 to 55%〉
*) The U value for wooden stick-framing construction (regulatory notice compliant specification) is calculated with QPEX2.0. The inflow and outflow of heat from the ventilation layer to outside is not included in the calculation. The effect of thermal bridge in wooden parts is already included in the calculation.
Fire-resistant wooden structures are excellent in thermal insulation performance.
Because the indoor temperature change is small, it is possible to save the running costs for air conditioning.
【③ Short depreciation period】
With wooden structures, it is possible to write off more annual depreciation than reinforced concrete structures and steel structures.
*) In case of newly-built hospital (depreciation period may vary according to the decision of each tax office)
In addition, there are tax advantages as well.
【④ Wooden construction is useful for saving costs】
〈Comparison of construction cost (example)〉
(Building with floor area of 1000 to 2000 m2)
Source: based on the “Guidelines on the Promotion of Utilization of Wood in Public Buildings” by the City of Yokohama
Useful points for saving costs
- ・With wooden construction, it is possible to use pre-cut technology, which enables the construction period to be shorter.
- ・Wooden structures are lightweight, which enables to reduce the cost of construction for footing/foundation.
【Usage and regional division of fire-resistant wooden structures】
【⑤ Reduce CO2 footprint】
Using wood may lead to the reduction of CO2 footprint, etc., which makes it also effective for companies to improve their CSR.
In addition, by using locally produced materials, it can be expected to bring the revitalization of industrial activity.
CO2 emission during construction for each construction method when constructing one house （kg-CO2）
*) Under assumption that the floor area is approx. 125m2
【⑥ Preferred “comfortable wooden house”】
When people interested in building or buying a house in the future in Japan were asked about which construction method to use , 8 out of 10 people answered that they would like to choose a house constructed of wood. Various charms such as the warmth of wood and relaxing effect are well known.
“Public Opinion Survey concerning Forest and Livelihood” Source: based on the Cabinet Office.