At 3,500-square-feet, the three-story house is firmly embedded into its sloped site, which overlooks a valley with a densely forested hill in the distance. The ground floor, is a basement bunker used as a guest apartment. This submerged level gets natural light through a lightwell above. The first floor, or “garden” floor contains kitchen and living areas, and is, according to Kratzenstein, “a composition of boxes and levels embedded into the topography of the site, and glazed all around to make the transition between living area and orchard lawn as seamless as possible.” Then there’s the top floor, an aluminum-composite clad wedge that seems to hover above the ground. Adding to the aerospace effect are two remote controlled, trapezoidal shaped roof overhangs that are mounted on a shaft rotated by a telescope-motor. A push of a button raises or lowers the overhangs, letting a sky view and light from above flood the living room, and shading the space from harsh sun as needed. “The aluminum relates to automobiles and planes,” says Kratzenstein. “We wanted to amplify the look and feel of a moving vehicle instead of a static object.”

The three children and their parents each have bedrooms on that top floor, oriented toward the east and southeast for morning sun. There’s an outdoor deck on this upper story made of a tropical hardwood called Bangkirai (Kratzenstein says it came from a certified source). Interior furnishings and materials are common and functional—parquet floors and plastered walls on the top floor and concrete floors on the two lower floors, as well as slate in the entrance and bathrooms, and inexpensive plywood with a matte finish for built-in furniture throughout. Outside the house, layered concrete shapes persist, as a sunken cement pool and stepped patio area provides the family with extra space to live and play. “The family loves how the house integrates living areas into the garden space,” says Kratzenstein, who says the site itself is incredibly beautiful. “The house has a view to where no further construction is possible,” he says, adding, “there's a little zoo nearby and you can hear giraffes and elephants roaring in the evening. On the terrace of the top floor you even get a glimpse of Frankfurt's skyline.”