Donghua South Road in bustling Taipei, Taiwan, is not unlike a busy street in your average Asian metropolis—say Shanghai, Hong Kong, or Bangkok. The district mixes mid-rise and high-rise, commercial and residential. Also something of a hyrbrid is the Donghua South Road apartment that Ivan Tsai, a bachelor in his 30's, commissioned from CJ Studio.

Tsai asked principal Shichieh Lu to take the 3,200-square-foot floor-through and carve out a self-contained unit for his parents, who come to stay regularly. In essence, as the architect puts it, he designed a "house within a house." The resulting apartment works equally well as a single unit or as two distinct ones, each with a bedroom and even a sitting area. Lu describes the setup as "modern—but with a little bit more freedom."

After gutting the apartment, Lu installed a cement floor and coated it in smoky-gray epoxy, polished to a high gloss. Then he divided the long space in half, creating a shared open kitchen and living area in the middle. The parents' end is a bit more conventional, with a standard bedroom and bath. At the other end is the bachelor's house-within-a-house, a freestanding structure built of white-painted plywood and MDF and oriented on a diagonal.

This futuristic intervention starts out as the platform floor of the master bedroom, then rises behind the bed to form a wall that, in turn, folds down to become, first, the ceiling of the master bathroom and, next, its rear wall. In this way, a single element simultaneously unites and partitions bed and bath while playing with the idea of inside and out. "I like to create an exterior feeling on the interior," Lu says. "Here, the bedroom platform becomes the outside, and the bathroom is the inside."

Clear glass encloses the otherwise open sides of the bathroom, where custom fixtures and fittings appear in pairs. Below a pair of rectangular mirrors, suspended from the ceiling, two boxy white Corian basins are mounted at the foot of a square soaking tub. Stainless-steel showerheads, two of course, are actually outside the bathroom: They're mounted on the back of the enclosure's rear wall, which also contains plumbing for the bathroom as a whole.

Lu specified stainless steel for the appliances in the kitchen, too. "My style could be described as industrial minimalism," he notes. But that's certainly not the case for the showstopping kitchen island, a faceted iceberg of white acrylic.

On the outside of the island, he placed a leggy Marc Newson table and surrounded it with chartreuse polypropylene shell chairs by Charles and Ray Eames, whose seating designs are sprinkled throughout the apartment. A white-upholstered lounge chair and ottoman sit alongside Rodolfo Dordoni's sectional in the living area. A sky-blue rocker occupies the no-man's-land between the living area and master suite. And aside chair accompanies Jasper Morrison's zip-together modular sofa in the master bedroom's own sitting area.

The sitting area faces the back of the bedroom's plasma-screen TV, which is mounted on a 2-foot-high pole, like a squared-off lollipop. So Lu had the white-painted stainless-surface laser-cut in a computer-graphic pattern that could be digital artwork. "Sometimes, the back is as important as the front," he says, sounding as wise yet inscrutable as an ancient Chinese proverb.

In this apartment in Taipei, Taiwan, a freestanding structure of painted plywood and MDF houses the master bathroom.

From top: The enclosure separates the master bath, with its custom Corian sinks, from the master bedroom, where bed and table are also custom. Showers are mounted on the opposite side.

Right, from top: Ducts for heating and cooling are concealed in the dropped ceiling. Epoxy covers the cement floor. Cotton curtains and glass partitions partially close off the master bedroom's sitting area.

Clockwise from top left: Jasper Morrison designed the sofa in the master bedroom. The kitchen island is acrylic. Rodolfo Dordoni's sectional anchors the living area. The kitchen features chairs by Charles and Ray Eames and a table by Marc Newson.

SINK MATERIAL (BATHROOM): DUPONT. SHOWER FITTINGS: COSMOS. SOFAS (BEDROOM, LIVING AREA), TABLE (KITCHEN): CAPPELLINI. CHAIRS (BEDROOM, KITCHEN): HERMAN MILLER THROUGH YAHO. HOOD (KITCHEN): EURO-MOBIL. FLOORING: ARDEX. LIGHTING CONSULTANT: JU-XIN LIGHTING. GENERAL CONTRACTOR: YAO HONG DECORATED CONSTRUCTION.