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The stark wall serves the double function of providing a security barrier and, because it is physically separate from the house, moderating the inner environment by absorbing solar energy from the northeast. This is the sun's most powerful direction in the southern hemisphere, and such a barrier is essential during Santiago's very hot summers.

The blunt concrete street facade is broken only by a monumental wood door that seemingly extends from the floor to the top of the house. But this is an illusion — a standard-size door is topped with a panel of the same material, a feature used on doors throughout the design.

Dwelling Elements and Circulation

The street door opens into an inner courtyard. A second door opens into the house, which has three staggered levels connected by a spinal column of connecting wood-floored ramps lined with a canal of recessed floor lighting.

The switchback ramp network mirrors the topography of the site and opens up a light, airy space in the heart of the house. A bank of windows allows light to enter from the narrow bamboo garden that separates the wall from the house, which receives more light than one would expect considering the proximity of the concrete wall.

The ramps all dogleg, mimicking the irregular profile of the mountains, creating a counterpoint of jagged lines within the boxy shell. Where the ramps angle, holes are created that allow light to pass through the house from a skylight that matches the shape, dimension, and positioning of the ramp doglegs.

The ramp descending to the children's level houses a bank of storage closets serving the three bedrooms. The ascending ramp leads to the intermediate central level where the dining room, lounge, and kitchen are, before it switches back and rises to the upper level that contains the master bedroom suite and roof access.

Materials and Form

The house maintains a low horizontal profile from the street in accordance with the client's desire to maintain the scale of the countryside. The cornice is horizontal and cuts across the mountain plane, while the "floor melts with the existent topography," according to the architect, descending with hillside.

The structure is a practical, reinforced concrete shell supported by pillars. It gives a rigorous formal economy complemented by an expansive glass facade that provides a humanizing counterpoint, maximizes the view of the mountains, and allows natural light to enter each bedroom and the family room.

"We used simple, traditional technology," says Undurraga, citing design influences such as Louis Kahn and Frank Lloyd Wright. "Its strength is in its relation with the geography as it is a project that is deeply rooted in the physical place."

The construction is "high-low tech" in that it combines traditional materials and construction techniques with the benefits of modern technology. "I like to work with traditional materials but using technology to improve the quality of the building," Undurraga says. "Nothing is prefabricated. Concrete is primitive and artisanal, while glass is the material for the 21st century."

He thinks of concrete as "synthetic rock" that sympathizes with the mountains. The material is overtly presented throughout the house as undressed columns, in bare concrete ceilings with a precise wooden slat pattern, and with rectangular imprints of metal moulds into which the concrete was poured.   >>>

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SUBSCRIPTION SAMPLE El Mirador, by architect Cristián Undurraga, presents a sober concrete face to the street. Photo: Guy Wenborne High-ceilinged living spaces front the terraced back yard. Photo: Guy Wenborne A narrow courtyard separates the house from the concrete facade. Photo: Guy Wenborne Small openings in the concrete facade protect the occupants' privacy while admitting light to the glazed inner wall. Photo: Guy Wenborne Lower floor plan. Image: Cristián Undurraga Upper floor plan. Image: Cristián Undurraga Building sections. Image: Cristián Undurraga Building elevations. Image: Cristián Undurraga   Click on thumbnail images to view full-size pictures.