This master bath breaks the mold of the traditional lavatory: not only is it uniquely integral to the success of its adjacent bedroom, it also contends with challenging site conditions. One would hardly suspect all that is at play here, thanks to a meticulous execution by Chicago-based Studio Dwell Architects.

Although the partly underground bedroom features large windows that frame and overlook the river, it receives relatively little sun until late in the day because of their westward orientation. To rectify this, the architects built an 18-foot-wide, 8-inch-thick concrete wall between the sleeping and bathing areas that stops 2 feet short of the ceiling, allowing the bath's abundant daylight to spill over.

“When [the clients] wake up in the morning, they have this nice eastern light coming in across the ceiling plane,” says Mark Peters, principal of Studio Dwell Architects. In the evenings, both rooms benefit from artificial light that is concealed within a recess in the top of the wall.

In addition to the clerestory, the architects applied other design strategies to accentuate the length of the 8-foot-6-inch-wide-by-24-foot-long bath. Rectangular porcelain tiles create a grid pattern that moves across the floor and up the walls behind the glass corner shower, further enhancing a forced perspective. Two 12-foot-long rows of drawer units (one used as a vanity) were mounted to the wall in parallel with the lines below. They were staggered to further create the impression of depth.

The washroom's neutral palette and clean design instill calm and render the space a canvas for the dramatic light streaks painted by the sun throughout the day. The large-format tiles have a sandy-gray hue, while the vanity features a wenge-veneer finish and concrete-tinted quartz countertops. Save for the concrete, glass, and tiled walls, the remaining vertical surfaces were painted beige, making the white freestanding, oblong tub a sculptural focal point.

Finally, the generous shower-with-a-view and its neighboring private terrace reinforce the spa-like feel. The shower window faces the outdoor enclave, which is accessed from the bedroom and outfitted with smooth stones and ipe wall paneling. The layout affords bathers vistas down to the Fox River, while a partial wall at the end of the terrace helps shield them from prying eyes. Like the rest of the house, the terrace is partially embedded in the earth, with one side functioning as a retaining wall, connecting this retreat both figuratively and literally to the surrounding landscape.