Stella Betts and David Leven have been partners in design and life for almost 20 years, and one of their most recent projects has brought them back to the earliest days of their practice. Named for its straightforward geometry, the Square House—a concrete guest cottage and spa—was methodically cast in place just behind the architects’ very first ground-up residence.

Additional Information:
Jump to credits & specifications

The duo established their firm, LevenBetts, in New York in 1999 and built a spec house in the Hudson Valley four years later. It piqued the interest of their friend Andrew Zuckerman, a photographer who had visited the site on a whim to shoot the freshly poured slab. Today, those photos hang in the living room of the home, which Zuckerman and his wife purchased as a weekend retreat—and used as the locale for their wedding. More than a decade (and three children) later, the couple reenlisted LevenBetts to design a relaxing backyard getaway for their guests—and themselves. Hiding a varied section and program within a simple plan, the one-bedroom structure is inspired by traditional Japanese inns, or ryokan.

“The project was conceptualized around the idea of bathing and observing nature,” says Leven. A steam room, jacuzzi, and Japanese soaking tub, all made of hinoki wood—a rot-resistant variety of cypress native to Japan—comprise roughly one-quarter of the 1,600-square-foot structure. Operable skylights bring diffuse light to the space, which contains a small atrium with a ficus tree and looks out on a landscaped moss garden.

To further connect inside and out, the architects used oak harvested from the woody site to build cabinetry, and added oversized glazed openings—all of which can be recessed into wall pockets—to each side of the house. They also made many of the building’s amenities accessible from the exterior: the structure’s signature concrete stair leads to a roof garden, which serves as both an open-air living room and an elevated campsite for the kids; the modest bathroom opens to the yard through a narrow, retractable frosted door; and a large outdoor sink, which seems to extend through the glass as an offshoot of the kitchen counter, provides a place to wash up. With all the glazed doors retracted, the Square House becomes more pavilion than building. “We wanted the design to highlight how small the house could be but how big it could feel,” says Betts.

To that end, interior spaces were also created to serve multiple purposes. In the sunken den, a sofa designed by the architects becomes prime real estate for sleepovers, and for movie watching when a retractable screen is lowered, while a studio, with discreet doors and a Murphy bed, quickly transforms into a second bedroom.

In both form and material palette, the guesthouse, firmly rooted in the earth, stands in stark contrast to the wood-clad original. “They have two different ways of responding to the landscape,” says Betts. Where the main building adjusts to the land externally, perching and cantilevering on the sloped site, the Square House negotiates changes in topography internally, incorporating steps and drops within its section.

The architects chose cast-in-place concrete for its monumentality and texture, working with an expert contractor to build elaborate formwork that left notable striations from roughhewn boards on long faces, but smooth surfaces on doorways and entries. “It took more than a dozen pours,” says Betts. “It was a puzzle, but it was amazing.”