Onodatesho Pavilion 2026: Timber Structure in Ehime

Crafted for Japan's annual National Tree-Planting Festival dedicated to forest preservation, the Onodatesho Pavilion served as the ceremonial structure hosting the Emperor and Empress during the day-long event. Since 1950, Japan has commissioned a temporary piece of state architecture for this festival, with the ceremonial pavilion traditionally dismantled shortly after the proceedings conclude.

For the event located in Ehime, Yano Aoyama Architecture Design developed a timber structure combining large cross-laminated timber (CLT) panels with a simplified structural system centered on material reuse. The largest transportable CLT panels in Japan, measuring 12 by 2.3 meters, were kept substantially intact. Rather than relying on extensive cutting, the overall geometry was achieved through six operations: tilt, rotate, lean, taper, shift, and cut, all coordinated via a single repeating joint detail.

Stock photo for illustration only, not from the actual event

The pavilion consists of three principal asymmetrical planes rotating around an imaginary axis. One of the main wooden masses leans ten degrees toward the audience, referencing the profile of nearby Mt. Ishizuchi and supported by slender steel rods. These planes are strategically positioned according to ceremonial sightlines and sun protection needs, echoing the festival's core theme of renewal: plant, grow, use, repeat.

Developed in collaboration with local carpenters, CLT manufacturers, and drafters, the structure bridges regional timber traditions with contemporary production techniques. Cedar and cypress sourced directly from Ehime establish a tangible material connection to local forests, while the implementation of large CLT panels highlights advancements in regional timber engineering.

Material reuse permeates the entire temporary construction process by Yano Aoyama Architecture Design Studio. Off-cuts from the primary CLT panels are integrated into secondary elements such as the stage stairs. Following the conclusion of the festival, the main panels can be unbolted and repurposed within the regional school network as custom furniture, embedding the temporary lifecycle directly into the architectural strategy.

Source: designboom