TREE HOUSE

Bercy Chen Studio engineers a warmly welcoming modernist home in Texas Hill Country

- FRED A. BERNSTEIN

After buying 10 wooded acres on a steep slope along a creek in Austin, Mary Mandel and Jaime Delgado had to decide exactly where to put their house. "We didn't want to look out over the trees," Mandel says, explaining, "We wanted to be in the trees. We wanted to see owls nesting on branches and red-tailed hawks bathing in the creek and bobcats chasing rabbits. We wanted to have an intimate relationship with nature."

But, Mandel says, "there was only one place where I knew we would be able to achieve that, and it was the most challenging part of the site to build on"-a limestone shelf, known as the rimrock, 20 feet above the creek and more than a quarter mile from the nearest road. Mandel, a California native, took a while to find an architect daring enough to help her realize her vision. "Most preferred a more conservative approach," she recalls.

But then she met Calvin Chen and Thomas Bercy, who started out designing houses in Austin 22 years ago. Though they now devote much of their time to larger buildings (including affordable housing), they continue to design single-family homes. The firm approaches every project as a fresh creative inquiry. "We provide solutions that take into account the site's constraints and its natural qualities," says Chen. This was just what Mandel and Delgado wanted. After hugely successful careers that took them around the world, the couple had decided to move back to the US with their son, Drake, 12, and build a home suited-aesthetically as well as functionally for the next phase of their lives.