Construction Begun on “Southwood,” the First Large-Scale Fire-Resistant Wooden Commercial Facility in Japan

—Realizing a wooden structure in a fire prevention district in front of a station by using “Moen-Wood®”wood material that has fire-resistant properties—

June 27, 2012Takenaka Corporation

On July 1 this year Takenaka Corporation (President: Toichi Takenaka) will begin construction of “Southwood (Tsuzuki-ku, Yokohama),” which will become the first large-scale fire-resistant wooden commercial facility in Japan. The order was received from Yokohama Urban Future Create Co., Ltd. (President: Hisayuki Tanaka). This facility, which is planned to be completed by September 2013, is located on a site in front of Center Minami Station on the Yokohama Municipal Subway, in a northern area of Yokohama where development continues. The facility will have one below and four above floors.

The total production of this project is being carried out by CIA Inc., and the design was created by E.P.A. Environment Conversion Equipment Building Laboratory First-Class Architects (structural design: Takenaka Corporation; equipment design: SOGO Consultants). With the concept of a “Green Neighborhood,” the aim was for an environmentally-friendly building with the introduction of “wooden” parts as much as possible. Specifically, “Moen-Wood®,” a fire-resistant laminated lumber developed by Takenaka, which is composed of wood material (larch) with a fire-resistant mortar layer on the inside, is being used for the main structure (columns and beams) in the second to fourth floors.“Moen-Wood®”has the one-hour fire-resistant property required by the Building Standards Act, enabling the construction of a wooden building with a large nine-meter span (space between columns.)

Up to now it has been difficult to construct large-scale wooden structures in a fire prevention district such as this project, because of the fire-resistance properties of structures required by the Building Standards Act. The use of “Moen-Wood,” which is certified by the Minister of Land, Infrastructure, Transport and Tourism as column and beam fire-resistant laminated lumber (FP060CN-0484 for the columns and FP060BM-0311 for the beams) has realized the construction of this large-scale wooden structure.

Perspective image of “Southwood” after completion

※This image shows how the facility will look after completion, but there may be differences in the building and the building use.

Background of the wooden structure market

The “Act for Promotion of Use of Wood in Public Buildings” (which came into effect in October 2010) calls for the promotion of the creation of living environments making use of domestic forest resources which are gentle on people. Presently, the national government is taking the initiative and focusing on increasing the use of wood in public buildings, where use is very low, and it is also proactively promoting use by local governments and private companies, aiming to largely increase overall demand for wood, including ripple effects on the housing and general construction markets.

“Moen-Wood®” will contribute to the spread and development of the construction of large wooden public structures such as schools and hospitals in fire prevention districts, where planning has been difficult up to now because of fireproof and fire-resistant regulations. The use of the product in commercial facilities and large offices in fire prevention districts will contribute to providing living environments which are gentle on people, the development of the construction and forestry industries, and the conservation of the natural environment.

Using “Moen-Wood®”to realize larger spans

“Moen-Wood®” was developed in 2007※ as a one-hour fire-resistant laminated lumber using cedar material for use in the columns and beams of wooden structures to enable a large span (length between columns) of 4.5 meters, and was certified by the Minister of Land, Infrastructure, Transport and Tourism. Later, in order to meet the requirements of nine-meter spans for commercial facilities and offices in city centers, the material was changed to higher-strength larch. In December 2011, the new product was also certified by the Ministry of Land, Infrastructure, Transport and Tourism. This means that a four-floor fire-resistant wood building, or a fire-resistant building with a wooden section of four floors from the top floor to the fourth floor down can be constructed with an ordinary building certification application.

In 2009, Takenaka constructed the New Fire-Resistant Laboratory, the highest-performance facility of its type in Japan (load capacity of thirty meganewtons (MN) over eight hours of heating). Fire-resistant performance can be evaluated using actual-size members, opening up new opportunities for“Moen-Wood®.”

※ Aid received from the New Energy and Industrial Technology Development Organization and the Ministry of Land, Infrastructure, Transport and Tourism.

How “Moen-Wood®” secures fire-resistance performance

“Moen-Wood®”is a fire-resistant member, consisting of a “load support part,” which is laminated lumber (layered lamina fixed together using adhesive), a “burn stop layer,” and a “substitute burn layer” on the outside.
Larch is used in the “substitute burn layer.” Should a fire break out, the “substitute burn layer” becomes a high-performance fire-resistant char layer, inhibiting burn progression. Mortar and larch are set out alternately in the “substitute burn layer,” so the mortar absorbs the heat, stopping the burning and thereby safely protecting the “load support part” from the fire.

  • Cross-section 1 of a “Moen-Wood” column

  • Cross-section 2 of a “Moen-Wood” column

Outline of the “Southwood”

As a large-scale wooden building using a large amount of recyclable circulative resources, this project has been accepted as “work implementing leading wooden construction technology” (previously “work promoting wood urban redevelopment”) as defined by the Ministry of Land, Infrastructure, Transport and Tourism. As such, some aid is available.