Dazaifu Tenmangu is a 1,100-year-old shrine in Dazaifu City, Fukuoka, Japan, that is one of Japan’s most popular tourist attractions, drawing about 10 million visitors annually. A temporary hall was required during a major renovation of the main hall. Designed by Sou Fujimoto Architects, the temporary hall features a modern ‘living roof’ concept, paying homage to the main hall’s large cypress bark roof and traditional Japanese architecture style.

Arup provided structural engineering services for this cutting-edge temporary hall, mixing old and new elements through a combination of traditional and modern architecture. With only three months for construction, a quick and simple structure was required to fulfill more complex needs. Buried cultural properties meant excavation was not possible, so our engineers designed an expedited build with above-ground foundations.

It was important to maintain the historic and spiritual uniqueness of the shrine, while still encouraging tourist visitors. The unique forest-like roof plantings create a harmonious landscape that seamlessly blends with the surrounding mountains, buildings and natural environment, while concealing the main sanctuary undergoing renovation. Doing so in a circular manner – with all of the plants being transplanted within the shrine’s precinct at the end – was a key final feature.

Temporary hall for Dazaifu Tenmangu. Credit: Masaki Iwata+Sou Fujimoto Architects
The edge of the roof achieves a thin eaves of 4m with planting on top. © Masaki Iwata+Sou Fujimoto Architects
Temporary hall for Dazaifu Tenmangu. Credit: Masaki Iwata+Sou Fujimoto Architects
The forest-like structure exudes a unique presence while seamlessly blending into the surrounding natural environment. © Masaki Iwata+Sou Fujimoto Architects

Structural engineering

Due to the presence of buried cultural properties, excavation of the site was not possible. Instead, a steel plate was laid on top of the ground and a concrete foundation was constructed. To address drainage needs, an innovative above-ground drainage system was implemented.

To expedite the construction process, early-strength cement, capable of achieving the specified strength within approximately three days of casting, was utilised. Since concrete was only used for the foundation, horizontal braces were strategically positioned to stabilise the roof surface and transfer seismic and wind pressures to the earthquake-resistant structure.

The roof tip was designed to extend 4m with plantings on top. The structure is a one-storey, braced steel frame, assembled from transportable parts that can be bolted together without on-site welding, enabling a swift construction process. The centre of the roof is thickened to provide ample soil depth for planting trees over 5m tall. This ‘bowl’ shape also facilitated the design of a lightweight roof, thin at the edges, with low eaves at the front, and upturned at both ends. This allowed for a curved ceiling in the worship hall, mirroring the shape of the roof. 

The roof is mainly covered with evergreens, including camphor trees, a symbol of the Tenmangu Shrine. Shrubs, flowers and colour-changing plants, along with deciduous varieties such as autumn leaves, cherry blossoms and plum blossoms are incorporated to create a seasonal ambiance. The roof hosts a diverse array of 66 plant species, with the soil depth adjustable to suit each plant.

Temporary hall for Dazaifu Tenmangu. Credit: Masaki Iwata+Sou Fujimoto Architects
The temporary hall was built for a three-year period of use in conjunction with the first major renovation of the main hall in 124 years. © Masaki Iwata+Sou Fujimoto Architects
Temporary hall for Dazaifu Tenmangu. Credit: Masaki Iwata+Sou Fujimoto Architects
The plants and trees will be transplanted to the precinct after the temporary shrine has fulfilled its purpose for three years. © Masaki Iwata+Sou Fujimoto Architects