西崎組が小豆島で手掛けた、CLT工法で島の建設課題に応える〈港のオフィス〉

Shodoshima Island in Kagawa Prefecture, situated in the Seto Inland Sea, is widely recognized as a major producer of olives. However, it has also been a source of granite—known since ancient times as “Shodoshima Stone”—and high-quality stones from the island were transported across the sea to be used in the stone walls during the reconstruction of Osaka Castle.
The site is located on the eastern side of Shodoshima Island, and Fukuda Port, situated right next to the construction site, serves as a key transportation hub for traffic from the Kansai region, connecting to Himeji Port via a shipping route. The area surrounding the site offers views of the calm waters of the Seto Inland Sea, with the steep mountain ranges—where Shodoshima’s distinctive granite is exposed—rising behind it.

A construction company headquartered in Kobe operates a crushed stone business on Shodoshima and is seeking to expand by establishing a new facility there. Employees spend their days in the mountains, covered in dust as they repeatedly extract and crush stone—a grueling line of work. However, the president felt that precisely because of these harsh working conditions, he wanted to create an office where employees, at least when they return to the company after a day’s work, could not only escape the heat and cold but also enjoy Shodoshima’s beautiful scenery and a moment of tranquility.
Viewing this as a major issue for the future of this “island of stone” amid a significant decline in the number of workers in the crushed stone industry, he sought to express an architectural style true to the region without overreaching.
The goal was to create a building that embodies “a new hub for business expansion,” “a warm architecture that contrasts with the harsh working environment,” and “design that solves problems in the local community.”

Rather than fighting the site’s irregular shape, we segmented and arranged the space to create a large, functionally cohesive main area alongside smaller spaces, such as wet areas. Between these two volumes—one large, one small—we omitted a traditional corridor. Instead, we designed a staircase that creates an engaging sequence of spaces, allowing people to move about intuitively. Situated along an axis connecting the mountains and the sea, the building occasionally offers glimpses of the surrounding landscape, creating diverse spaces that transcend the specific functions of individual rooms. While the use of traditional post-and-beam construction methods—such as “makabe” (exposed timber walls) and “ōkabe” (large-panel walls)—tends to diminish the perception of the wood’s surface, this design employs an “open-and-closed” approach to the surfaces to allow occupants to experience the inherent texture of wood and the beauty of its grain when it absorbs light. This space, which is gently connected yet subtly segmented, creates an atmosphere where one constantly senses the presence of others and remains aware of nature, even within a multi-story office environment. Here lies a unique charm that could not have been achieved without CLT. Freed from harsh working conditions, employees will be able to relax in this warm space and enjoy a moment of respite.

We took on the challenge of realizing a CLT double-skin system composed of structural panels that leverage CLT’s strength and fire resistance, and finish panels that utilize their lightweight nature and high thermal insulation performance. The finish panels are 36 mm thick—the thinnest in Japan—and bear no structural load. While the structural panels support the weight of the finish panels, the installation of 60 mm vertical furring strips creates airflow between the two CLT panels due to their own weight. By applying “Silicone-Based Super Hydrophobic Coating S-100” to both sides of the finish panels, we can prevent water from penetrating the wood. While UV exposure will cause discoloration over time, the wood’s natural texture will be revealed, allowing one to appreciate the passage of time. Furthermore, even if deterioration is discovered, the impact will be limited to the finish panels alone, since they are lightweight and replacement is relatively easy. By leveraging these advantages, the building’s form will likely remain a lasting presence in this area for many years to come.

Issues in the construction industry—such as the aging workforce, labor shortages, and stagnation in workforce development—are likely to become major regional challenges for Shodoshima in the near future. For this project, we brought together our own veteran carpenters and young carpenters dispatched from Takamatsu to work collaboratively. Thorough prefabrication led to reduced material waste, shorter construction schedules, and fewer labor hours, and also facilitated “joint technical training.” Although all team members were inexperienced and this was their first time working with the CLT construction method—and progress was not as smooth as hoped at first—the project was completed through a fusion of the veterans’ experience and adaptability with the younger workers’ flexibility and efficiency. We felt that “collaborative skill development” is one solution to the challenges facing the construction industry that will lead to a brighter future.
(Nobuhito Nishizaki)

Location: Shodoshima-cho, Shozu-gun, Kagawa, Japan
Principal use: Office
Client: Shinei Kensetsu
Completion: 2025

Architects: Nishizakigumi
Design team: Nobuhito Nishizaki
Structural engineer: Kurashiki Structural Design Office, MEIKEN LAMWOOD
Equipment: Itami Facility Design Office, Tomiyama Setsubi Sekkei
Design cooperation: 4FA
Construction: Nishizakigumi

Photographs: Miyake Nobuki

Construction type: New building
Main structure: Mixed (Wood, S, RC)
Site area: 323.75m²
Building area: 181.34m²
Total floor area: 412.96m²
Design term: 2024.01-2024.07
Construction term: 2024.08-2025.04