To the north of Luxembourg City, an origami of a house clings to the steeply sloping terrain. Step inside and it is clear this is a home with an utter disregard for symmetry, straight walls or conventional geometry.
"So many houses just look the same. We did not want to build a house which looked like a shoebox," says Eliana d’Alimonte, a 40-year-old high-school teacher, of her home in the small European country of Luxembourg.
Mrs. d’Alimonte and her husband, Valerio, 45, spent 18 years saving up to build a modern home. They bought a small apartment in Luxembourg City in 1998 and patiently worked their way up the property ladder from there, renovating homes and even building two apartments.
In 2008, the couple paid €400,000, or about $450,000, for a sloping 4.5-acre lot that had formerly been used to grow fruit and vegetables in Mühlenbach, a leafy neighborhood 2 miles north of the city center.
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They asked François Thiry, a partner at Polaris Architects in Luxembourg, to design something fresh, relaxed and creative. "We wanted a house which appeals to the senses, like an artwork, and that was maybe a little experimental," says Mr. d’Alimonte, who works for an organization that promotes Luxembourg tourism.
After six months of design work during 2009, Mr. Thiry came back to them with a plan for a geometric, four-story, concrete house molded into the slope of their tricky site. Inside the 2,691-square-foot home, the lower floor features a double-height kitchen and dining room, with one wall sloped sharply inward. A window has been carefully inserted into this inward-sloping wall, while to the rear of the room double glass doors lead out onto a small deck, with a short path leading down to a lawn.
Above the kitchen—and at street level—is a cutout mezzanine giving space for a living room and study overlooking the dining area.
To help furnish the oddly shaped space (no room in the house is a simple square or rectangle) built-in cabinetry and shelves display books on art, design, architecture and film. To bring in maximum light, a large picture window overlooks the garden.
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On the two upper floors are bedrooms for the couple’s children, Carlotta, 8, and Edgar, 6, and a family bathroom. There is a also "parents’ apartment" consisting of a double-height sitting room and, up a flight of stairs, a master bedroom tucked right into the very peak of the building, with an en suite bathroom and a small, private balcony.
Work on the two-year, $928,000 project began in the fall of 2010. Simply preparing the site and building the structure were engineering challenges that took more than a year to execute. First, a section of the hillside had to be dug out to provide a level lot, and deep foundations dug to prevent the house from slipping down the hillside. With the cast concrete structure, reinforced with steel, in place, work was able to begin on the interior.
The kitchen walls are clad in panels of concrete formed in timber molds to imprint a wood-grain pattern; still visible are circular marks in these walls made by the horizontal steel poles that supported the building during its construction.
"We did not want a polished house, and you can see the hands of the men who worked here," says Mr. d’Alimonte. "We also wanted to use a minimum of different materials so that it would be as simple as possible. We did not want a house that showed off."
The kitchen floor is pale gray polished concrete, and the room itself is skewered with sloping supporting columns. To complement this industrial feel, the kitchen cabinets and work surfaces are stainless steel.
An L-shaped sofa in a marmalade-orange is the only splash of color in the room—a deliberate decision. Mr. d’Alimonte says he wanted a house that was about "architecture not decoration" so as not to detract from features like a central staircase with concrete treads, and balustrades made of engineered wood.
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With its hard surfaces and sharp lines, anxious parents might see the d’Alimonte family home as something of a deathtrap. Carlotta and Edgar have adapted well, but when their friends come over, things are a little different. "The children want to climb up the walls and jump—we have to explain that it is not a playground," says Mrs. d’Alimonte.
And it isn’t only children who are fascinated by the origami house. "Sometimes we have been here and have been able to see a person with their nose up against the glass of the front door, trying to see what the house can be like inside," says Mr. d’Alimonte.