In Tokyo, Tetsuo Yamaji Architects has designed the Ginza Takagi Building, a twelve-storey mixed-use commercial complex on Ginza Sotobori Dori, a major thoroughfare running through the Ginza district. The structure’s top four storeys are timber-framed, giving it the appearance of a conventional steel-framed office block with a prominent wooden box set above.
Mixed-use organisation and hybrid structural system
The building’s lower floors and upper timber levels house commercial functions, while the intermediate floors accommodate offices and tenants. This arrangement results in a building whose exterior expression and structural system vary according to use.
The basement levels are constructed in reinforced concrete. Floors one to eight are built using a steel frame structure, with floors nine to twelve constructed in timber. Cedar wood grown in Tama, a city located in the western part of the Tokyo Metropolis, is used for the exterior walls of the upper levels and for the interior finishes of the ground floors.
The Ginza Takagi Building was completed in 2023 and inaugurated in May 2024. With a height of 56 metres, it became Japan’s tallest wooden skyscraper, exceeding the 55-metre, five-storey pagoda at Tō-ji Temple in Kyoto for the first time in three hundred and eighty years. Japan has a long history of tall wooden structures, particularly from the Middle Ages — however, the use of wood today is largely limited to small-scale, low-rise buildings, with little development of high-rise timber construction.
Edo-period alley typologies and partial timber construction
The Ginza district developed from an urban layout established in the early Edo (former name for Tokyo) period and is characterised by small- and medium-scale machiya — traditional wooden townhouses — arranged with their narrow sides facing the street. Between these buildings, narrow alleys extend towards the rear of the plots, where shops and galleries typical of Ginza are located.
The project replaces the former Ariga Shashinkan building on the site, originally constructed in 1966. The former building included a long-established restaurant in its basement and was a familiar presence in Ginza for several decades. From the outset of the project, the use of timber construction was considered as part of the site’s redevelopment.
During the planning phase, the possibility of constructing the entire building in timber was examined. This approach was ultimately found to be difficult in terms of compliance with fire-resistance requirements, structural performance, and cost. As a result, the timber structure was limited to the upper four floors, designed to achieve a one-hour fire-resistance rating. This approach was adopted for suitability within Ginza, a high-density urban area characterised by narrow, deep plots and tightly packed neighbouring buildings.
If a timber structure with high flexibility were used throughout the building, the structural frame would occupy a larger area. Combined with the need for two- or three-hour fireproof coverings, this would reduce the available rental floor area in a building of limited footprint. By confining timber construction to the upper floors and adopting a mixed structural system with steel framing below, the project accommodates the use of wood within a dense metropolitan context.
Each of the timber floors incorporates a balcony, with a roof terrace provided at the uppermost level. These open spaces reference the alley-like spatial character associated with the traditional urban fabric of Ginza.
Fire-resistant timber structure design
The timber section comprises four storeys formed as a continuous rigid timber-frame structure facing the street. Columns and beams are constructed using fire-resistant engineered timber members. The load-bearing members are clad with two layers of reinforced gypsum board, each 21 millimetres thick, with a 20-millimetre-thick timber layer used as the surface finish. This assembly is certified to provide one-hour fire resistance.
The design of joints is a critical aspect of fire-resistant timber construction. Fire-resistant timber members incorporating a flame-retardant layer must be detailed so that the cladding remains continuous. For this reason, drift-pin joints with inserted steel plates were adopted. The load-bearing timber members are carved to prevent bolts from interfering with the cladding. The sheathing and surface finish materials are installed on site after the structural members have been joined.
The same jointing method is used at the interface between the steel frame and the timber frame. As the accuracy of the steel frame affects the installation precision of the timber structure, the welded and installed steel plates were measured on site — both the timber joints and steel plates were adjusted accordingly. At the bases of the timber columns, steel columns extend up to 500 millimetres above the beams in bundled configurations, with base plates and gusset plates connecting the steel and timber columns. For the steel elements exposed above floor level, dry fireproof cladding using calcium silicate boards was applied to facilitate construction.
The Ginza Takagi Building’s structural system does not rely on contractor-approved construction methods and does not require a separate structural evaluation for mid- to high-rise mixed timber buildings. It is applicable to the small- and medium-scale multi-tenant buildings common in Japanese cities and offers a reference model for the broader adoption of mixed timber construction.
Fire-resistant exterior wall system
Within the timber structural section, wood is used for both exterior and interior wall construction. The exterior wall assembly consists of extruded moulded cement board, a steel-frame substrate, and panelised timber units fixed to the steel base. While the extruded cement board provides fire resistance, the timber used as the exterior surface material is also required to meet noncombustibility standards for fire protection.
The noncombustible timber exterior walls are designed for ease of replacement. Timber panels are fitted into a steel plate base and assembled as panelised units, with workability and long-term maintenance taken into account. This exterior wall system was finalised following detailed mock-ups and exposure testing.
Towards an urban timber architecture
Timber construction in Japan has traditionally been associated with small-scale housing built using conventional post-and-beam methods, supporting suburban and rural townscapes and local construction industries. In this project, related principles are applied within a dense urban context through the vertical integration of a four-storey timber structure. A fire-resistant construction system allows the timber to remain exposed on both interior and exterior surfaces, demonstrating an approach to incorporating wood into urban architecture beyond surface treatment.
In Japan, the annual utilisation rate of forest resources is approximately 0.53 percent, compared with approximately two percent in countries such as Sweden and France. Japan’s forest stock continues to increase and underutilisation contributes to forest degradation. Appropriate material use is therefore required to support long-term forest maintenance. The application of adaptable timber construction methods in urban buildings forms part of broader strategies associated with achieving carbon neutrality by 2050.
In her memoir, photographer and writer Claire Beck Loos recalls architect Adolf Loos saying: ‘He pulls a matchbox out of his pocket: “You see … this is modern architecture! … the house of the future is made of wood … Modern architecture is: Japanese culture plus European tradition!”’. Around 1930, Loos explored urban layering through the insertion of plain concrete volumes as extensions to existing buildings. While timber structures were not realised in these projects, wood was extensively used in interior spaces, combining new construction layers with existing urban fabric through material differentiation. This approach is reflected in the Ginza Takagi Building, where timber is integrated as a distinct architectural layer within a dense urban context.
