There’s nothing like a limited set of options to get Austin architect Jay Corder really excited. So, it was a good day for Corder when builder Alan Muskin asked him to collaborate on a spec house on a sloping lot with a giant old oak tree in front and a live creek that wraps from back to side of the lot, designated by the city as an erosion control zone. “I love that,” says Corder. “You are forced to be humble and come to the design without preconceived notions.”

What the architect really means is that instead of feeling hampered by the restrictions placed on him by the narrow lot, the busy street, the unrepentant topography and city regulations, he refused to view them as negatives. “How can we embrace the creek?” he wondered. “How can we make our future homeowner feel that they aren’t on a busy street in the middle of town?” The black brick, white stucco, steel and Western red cedar two-story modernist dwelling stretches the width of the lot, the white stucco second story creating a horizontal layer over the cedar-and-glass first floor. Three black brick walls—one enclosing a front courtyard, another concealing the public area of the house and the third defining the downstairs bedrooms—punctuate the structure, reminiscent of the confident horizontality of Frank Lloyd Wright’s Pennsylvania masterpiece, Fallingwater. “The symmetry and rhythm of the volumes reinforces a sense of well-being,” says Corder. They made the house so appealing that the eventual buyer—a single father with two children—hired Corder and interior designer Kasey McCarty to add another bedroom and bath, as well as to orchestrate the interior design.

Corder’s plan was to celebrate the site, and the celebration begins the minute the front door is opened: A 15-foot-long entry faces a close-up view of the woods in back of the house, as if it’s a passageway into the woods. En route is a fete of domestic assets: The voluminous entry includes a sculptural stairway composed of hunks of white oak; the exterior’s black brick wall extends into the interior, accentuating one side of the central dining area and moving upward into the second-floor family room. “We needed to balance the drama,” says McCarty, who specified a sealed hot-rolled steel panel that floats high above the dining table but also functions as the back of the family room’s bookcase.

McCarty responded to the homeowner’s request for modern furniture with seating such as Mitchell Gold + Bob Williams chairs around the dining table and two leather chairs by Dellarobbia in the living room. “They fit like a glove,” she says of the swivel pieces that accompany a Restoration Hardware sofa and a classic Eames chair. Practicality triumphs in McCarty’s choice of a walnut table with a seam of Japanese butterfly joinery for the breakfast room. “They knew the table would get used all the time and it would get beat up,” she says, “but it is also beautiful.” The symbiosis of beauty and ruggedness is a theme throughout. For a site that wasn’t perfect, Corder and McCarty elicited the very best, endowing the house with an extra sensibility that makes living on a busy street overlooking an erosion control zone a daily exercise in aesthetic delight.