Materialised almost entirely in wood and stone, complemented by pleasing hints of water and light, and surrounded by a dynamic, transformative landscape, YEZO is a nigh meditative settlement. Developed as a private retreat by Hong Kong-based Laboratory for Experimental Architecture and Design (LEAD), on a site that is as novel as it is enviably isolated in the mountain ranges in northern Hokkaido, YEZO adopts a minimalistic approach with respect to its spatiality that is characteristic of Japanese architecture, while at the same time employing a sophisticated, computation-driven design for its swirling roof. This seemingly disparate union of design styles served as an opportunity for the designers to demonstrate how a ‘holistic’ design philosophy resulted in a structure that is “ecologically sustainable and practically feasible”.

YEZO finds itself perched atop a flat rock on the mountain slope, affording a 360-degree view of its stunning landscapes, one of many such in Hokkaido. Access to the site is envisioned through a winding timber walkway at the back of the house. Modest in size, the retreat consists of a single, unified living space: a fluid spatial layout that is centred around the concrete fireplace, topped by its elaborate roof that is visually reminiscent of the roningasa straw hat from popular Japanese culture. The face of the fireplace affronts a seating and sleeping area, connected to the outside viewing deck through continuous, peerless glazing. Apart from facilitating uninhibited access to the outside, interestingly ‘uncontained’ through an absence of rails or a parapet, the deck also peculiarly corners a three-sided hot onsen pool along its curved tip.

The central fireplace in exposed concrete serves the dual purpose of a definitive space distinction, between the living spaces in the front, and the utility spaces: the bathroom, toilet, and storage facilities, along with being the structural pivot for the pirouetting timber roof. The shell structure of the roof, defined by the architects as built on a lean tectonic system, comprises glue-laminated (GluLam) timber beams cantilevered from the concrete chimney that doubles up as a hollow column. The curved beams are designed and shaped to operate purely in tension which results in weight and material constructions of up to 90 per cent vis-à-vis conventional timber construction. Algorithmically optimised for fabrication from a single mould for economy of cost, delivery time, and a reduction in ecological impact, the beams are further tied through catenary-shaped GluLam rafters. Additional support at the overhangs is lent by v-shaped extensions of the outward curving beam, anchored to the ground.

The elaborate timber framework of the roof is finally clad with black slate, lending a contemporary look, serving even as a reinterpretation of the chalet, a quintessentially Swiss building typology. A spiraling staircase behind the fireplace provides access to a whimsically shaped, partially enclosed balcony on the first floor, overlooked by the narrowing chimney of the fireplace and the ‘tucked’ apex of the swirling roof atop it. The enclosure for this balcony is framed by a fold of the roof structure and patterned, frosted glass along its perimeter, allowing diffused daylight into the living quarters below.

While the designers at LEAD treated YEZO’s design odyssey as a testing ground for radical architectural intervention, its source of inspiration lies in retrospect. According to the designers, the processes found inspiration in “several pioneering engineers and architects who in the mid-20th century conceived radically new tectonic concepts aimed at reducing material use, and thus environmental impact”. The catenary timber roof assembly was particularly quoted to be inspired from the works of Kenzo Tange, Eero Saarinen and Frei Otto, who demonstrated the usage of similar roof geometries with their constituent structural members operating under pure tension, resulting in visually unique and functionally light-weight architecture.

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