design

Designing a Modern Day Treehouse in Austin, Texas

In Austin, a challenging site inspires an innovative, award-winning home design.

When a couple with a young daughter wanted to build a new house in a neighborhood near downtown Austin, Texas, they turned to Alterstudio Architecture, an architecture firm known for its organic and honest approach to modernist design.

“We did two previous homes for them,” explains Kevin Alter, who worked on the new house with a design team that included his fellow firm partners Ernesto Cragnolino, FAIA, and Tim Whitehill. “We knew them well, and we knew that they enjoyed the building process.”

With a request for a simple home that included spaces for the husband and wife to work from home (she’s a floral and interior designer, he’s in music management), the design process seemed like smooth sailing—until the site came into play.

The couple picked the neighborhood for its proximity to city amenities, its walkability, and the mix of modern and vintage homes. But the lot they chose was challenging. “It’s a 50’ by 150’ lot,” explains Alter, “which had an old, tiny house on it. Because the property drops off steeply from the street, it was considered unbuildable.”

The narrow, sloping lot—which overlooks a tree-filled valley—was also next to a busy street. Another design challenge: A 25-inch-wide Durand oak grew in the middle of the building envelope. With Austin city ordinances that protect mature trees and their root zones, it meant that any new house had to work around the tree.

However, a handsome, functional design sprang up from these challenges. “We like buildings that have a great deal of complexity,” says Alter, who is also an architecture professor at The University of Texas at Austin. “This design does not have single-mindedness.”

Collaborating with the homeowners, the Alter Studio design team created a three-level, 2,990-square-foot home that steps down the site’s slope. Largely turned away from the street, the home, with its cube-like forms, opens up to an inner courtyard and towards the valley’s treetops. At street level, the floor plan includes the courtyard and entry, which leads to the living, dining, and kitchen areas. There’s a small balcony off the living room that floats above the treetops, as well as a guest bedroom and bath.

The lower level is anchored by a family room, where the husband can play guitar, and a deck that offers access to the hillside. The master suite and daughter’s room are both upstairs.

To save the oak, the living room’s volume was suspended above the root zone and to one side of the tree, seemingly floating in midair, but actually balancing on two slim columns that rise up from the hill below.

“It’s very much a treehouse feeling,” Alter says of the living room, which has glass walls on two sides.

With materials that include cast-in-place concrete walls, hand-troweled natural stucco, grey-stained cypress cladding, black steel accents, perforated corten steel screening and gabion walls, the home is at once modern and low-key, blending into its woodsy site.

To fill the home with natural light, the design team took a cue from glass high-rises and used site-glazed window walls that provide unfettered views of the courtyard and valley, with solid ventilator doors allowing breezes.

“We were careful placing walls to block out neighboring houses which are very close, and to place the windows for both privacy and views.”

Inside, the home continues the simple-material theme. In the basement level, the natural concrete floor and poured-in-place concrete walls are juxtaposed with a tongue-in-groove cypress ceiling and a slatted cypress wall panel, meant to provide acoustic solutions for guitar-playing.

On the main level, the flooring is a more refined oak, and in the spare, open kitchen, sleek white cabinetry is warmed by oak display shelving and drawers. Next to the kitchen, a cypress wall hides the door to the walk-in pantry.

In the entry, a sculptural staircase, framed by a slatted wood screen, floats between floors, its chunky oak steps and steel beam construction reiterating the home’s use of honest materials. A window wall floods the stairwell with light.

Upstairs, the master bath includes a floating oak vanity, detailed with leather drawer pulls, as well as a sky-lit walk-in shower. A window in the daughter’s room seemingly pops out of the side of the house, creating space for a window seat that has views of the city.

When it came to furnishings, the homeowners kept things simple, bringing pieces from their previous homes and adding a few classics found online, such as a Hans Wegner Papa Bear chair and a Marcel Breuer Wassily chair. Art and colorful rugs detail the rooms.

“This house doesn’t need a lot,” says Alter of the interiors. “The home is a primed canvas for the owners’ lives. The shadows, the views, the breezes activate the spaces.”

Completed in 2017, the home’s design has achieved numerous awards, including a national 2018 AIA Housing Award and a 2018 AIA Austin design award.

photography by CASEY DUNN

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