flat timber slabs extend educational facility by NIKKEN SEKKEI

Nikken Sekkei expands educational facility using mass timber

Tokyo-based architectural, planning, and engineering firm NIKKEN SEKKEI constructs Showa Gakuin Elementary School West Wing, an expansion of an existing school in Ichikawa City, Japan. Attending to the protection of forest resources through a proper harvesting and planting cycle, Nikken Wood Lab, a department of Nikken Sekkei specializing in the research and development of wooden architecture, pursues sustainability and explores new possibilities for CLT as mass timber with the use of domestic wood. For the first time in Japan, a project utilizes two-way CLT flat slabs for the construction of a contemporary educational facility.

Located on a site featuring a two-kilometer stretch of cherry trees along the Mamagawa River, the project employs the two-way CLT flat slab method that requires no beams following urban planning regulations restricting building height and changes to the townscape. The construction allows for minimal floor-to-floor height and total building height while maintaining the same ceiling height as the existing school. The use of CLT reduces the weight of the structure and minimizes its load on the foundation.

The floor plan consists of regular classrooms on the south side and specialized study halls on the north side, using a simple 9-meter grid, a module of one regular classroom. The fittings are designed to fully open to the central activity plaza, forming an integrated and continuous space for class visits, open school events, and other occurrences.

all images by Gankohsha – Harunori Noda

exposed CLT slabs adorn the exterior and interior of the school

Exposed CLT is employed for the interior, generating an abstract composition of seamless continuity where the timber transcends the functions of the building, promoting students’ spontaneous creativity and spirit of exploration. Two layers of exterior eaves exhibit an expression of exposed timber base ends and shade, achieved through the detailed shifting of the top and bottom surfaces of the two-way CLT flat slab. Various parts of the building feature carefully designed CLT details with slits that create intricate light and shadow effects and emphasize the timber’s volumetry. The new building by NIKKEN SEKKEI design practice is filled with natural wood and aims to familiarize children with nature, stimulate their imagination, and educate them about forest resources and the global environment.

the project pursues sustainability and explores new possibilities for CLT as mass timber

wooden construction evokes awareness of forest resources

The diverse design approach promotes curiosity and awareness of forest resources and the environment, proposing an affordable scale of wooden construction. The building’s main parts, such as the wooden columns and beams, have a higher level of fire-resistance performance than legally required, with extra thickness that would prevent them from combusting in the event of a fire. This eliminates the need for compartment walls, providing a more flexible and expansive space where CLT is used as both the structural and interior material. The lean design, which fully exposes the structure and MEP, incorporates corridors and staircases designed to stimulate various activities and provide a space that encourages a sensory perception of the architectural process. Each element of the building is labeled with its species, origin of the wood, and equipment function to raise awareness of environmental and forestry issues. This environmentally conscious building contributes to the realization of carbon neutrality.

two-way CLT flat slabs are applied for the construction of a contemporary educational facility