Situated on a plateau a full mile from the main house, Lake|Flato’s 2,375-square-foot pool house has nearly wraparound views of Texas Hill Country. The clients, who own a large ranch where the firm has designed multiple buildings over the years, asked for a contemporary outdoor room like the open-air pavilions in Thailand, where the husband frequently travels for work.

Years ago, the spot had been marked informally with a fire pit and vintage Airstream trailer, smartly remodeled, that sat in the hot sun. “They thought we should pull the trailer away, but we said, ‘We love it, let’s design for it,’” says project architect Karla Greer. The new pool pavilion is composed of three simple elements whose materials echo those on the main house: ipe decking, an open steel superstructure with a roof that tips up to the south, and two thick Texas limestone boxes that run perpendicular to each other, blocking the summer sun and winter’s northwesterly winds. The smaller masonry volume holds a full kitchen and media center, both of which can be closed off with slatted Western red cedar doors. “The owners are huge cooks,” says Greer, so kitchen fittings are deluxe, including a Viking grill, a wok cooker, an oven, and a dishwasher. The larger box houses an indoor-outdoor bathroom, laundry, and storage. Through an opening is the Airstream, shaded by oaks. It sits under an arbor and was given a new deck. “The trailer was remodeled years ago with old longleaf pine floors and decorated with leather, and looks like something Ralph Lauren would have worked on,” Greer says. “But no one seemed to want to go there.”

In summer the pavilion collects the prevailing southeast breezes, and the tilted roof mimics the land’s natural topography. “We strove for a light, delicate structure whose job is just to shade people from the sun,” Greer says. Its Tinker Toy–like steel frame arrived on a truck and was bolted together in a day, then topped with Douglas fir planks and a standing seam metal roof.

With the fully equipped Airstream nearby, the pool house has evolved as another guesthouse, minus the walls, windows, and doors. The living area contains a custom furniture piece that invites lounging, naps, and nights under the stars. “When the couple is here, they use this space actively,” Greer says. “With so little light from any town, there are fabulous views of the stars.”

The visual context was as carefully considered as the structure. Using an enormous oak tree to the west as a reference point, the architects pulled the pool house back from the hill’s edge. “Rather than looking down the hill, you feel like you’re on an island in the landscape because all your views become distant views,” Greer says. “On misty mornings the mist comes just below the top of the plateau, so you feel like you’re floating in the clouds.”

Those effects are amplified by a planting design that blends in with the big picture: a swath of drought-tolerant zoysia turf where the grandchildren play, and a sea of native grasses that move with the wind. The pool interior, too, is covered in sandy-colored plaster that evokes the limestone bottom of the region’s rivers and creeks. All these gestures defer to the land, while rendering a formerly inhospitable site relevant again.