Before the Covid-19 pandemic, the owner of the River House frequently travelled from Hong Kong to Niseko in Hokkaido, Japan, for skiing holidays. Enamored with the area, he tasked Japanese architect Tomoyuki Sudo of SAAD (Sudo Associates, Architecture and Design) to build a holiday home in the town for his family.
A few years later, he decided to construct a summer home in the same region—and he again engaged Tomoyuki, who received his architecture training at the Southern California Institute of Architecture (Sci-Arc) and the Architectural Association School of Architecture in London.
The owner wanted an oasis where he could be surrounded by nature and isolated from close neighbors—and the site at the base of Mount Yōtei, right next to the Shiribetsu River, perfectly meets these needs. There are dense forests up north, and to the south the cheery, sunflower-colored Niseko Bridge rises above a crown of dense foliage.
"Here, his family can indulge in outdoor activities, such as swimming in the river, cycling, camping, and barbecuing in the open," says Tomoyuki. He designed the simple, 3,356-square-foot River House so that it would not distract from the serene environment. The single-story plan provides every room with direct access to the outdoors, bringing the occupants as close to nature as possible.
The straightforward interior plan prioritizes the picturesque views. "The ambiguity of space between indoors and outdoors is the central concept for this project," says Tomoyuki.
Two parallel walls along the north-south axis form the main organizing elements in the plan. Eight shorter, perpendicular walls on the left direct views toward Mt. Yōtei while dividing up the principal bedroom, living room, sheltered veranda, and kitchen, which are laid in a linear sequence along the home’s length.
These interiors open to a terrace that edges the home’s east elevation. "This in-between space is intended to be an interactive zone in any weather condition," says Tomoyuki. The extended eave of the flat roof provides ample shade in the summer and shelter from snow, should the family decide to visit during the colder months. Tomoyuki sloped the roof toward the rear to prevent snow stacks from falling on the exterior living areas.
Some of the perpendicular walls extend onto the terrace, drawing the focus outward while bridging the internal and external spaces. Sliding glass doors connect the interiors visually and physically with the world outside.
Tomoyuki designed the home’s circulation to mirror a walk in nature, where where the topography dips and rises organically. The sunken living room brings the landscape close to eye level when one is lounging on the sofa. In the principal bedroom, a timber platform provides an elevated view of the scenery from the bed.
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The central corridor is capped by a picture window that frames another natural scene. To the left of the corridor, Tomoyuki aligned two bedrooms and an onsen-style bathroom. Full-height sliding glass doors connect the latter to an outdoor terrace, where timber portals frame the verdant landscape.
Tomoyuki thoughtfully chose materials that harmonize with the context. "We selected natural and rough-textured materials for a more outdoor feel—so that it’s more like a pavilion than a house," says the architect, who employed two kinds of timber. Locally grown Hokkaido cedar clads the exterior, as well as the short walls aligned eastward. The material’s sinuous grains and knots lend visual texture and artistic character to these areas.
The home’s custom furniture and internal partitions are made from plywood. "Its simplicity and less pronounced wood grains contrast well with the Hokkaido cedar panels," says Tomoyuki. "Both materials are rough but rich in texture." The warm timber balances the cool concrete floors, dark-textured plaster on the long corridor wall, and light-gray, textured ceiling paint.
Beyond its plan and siting, the home’s strongest link to nature could well be its sustainability. Local wood has a lower carbon footprint than similar lumber shipped from far away, and eco-friendly insulation and double-glazed windows fulfill energy standards. In the winter, hot water pipes embedded in the concrete floors provides the occupants with comfort underfoot. The stored heat continues to warm the floor all through the night.
In the summer, the extended roof keeps the exposed concrete walls cool. Strategically placed, operable windows ventilate the house so efficiently that the air-conditioning system rarely needs to be switched on. Clerestory windows above the internal walls bring daylight deep into the plan, so the occupants don’t need to rely on electric lighting in the daytime.
Instead of a homogeneous lighting scheme, Tomoyuki concocted a mixture of cozy shadowed spaces, dim illumination, accent lighting, and daylighting. This chiaroscuro effect mirrors the spontaneity and contrasts found in nature.
Builder: Sudo Construction Ltd.
Structural Engineer: Kenchiku Keikaku Atelier
Photographer – Ikuya Sasaki
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