Case Study: Tree House by Aidlin Darling
Dense suburbs are a challenge for architects trying to give their clients both privacy and a restorative view of the landscape. Some houses reconcile the two startlingly well, even on a third-acre lot—and without fences or walls. For example, the house that Aidlin Darling designed for a young family in Palo Alto plays off its two mature stands of trees, flipping back and forth between introverted and extroverted, nested and exposed. Like a tree house, it gets the family close to nature while screening them from the neighbors.
“One thing we like to explore is the psychology of spaces, and in certain residential projects, the dynamic between public and private space,” says principal David Darling, AIA. “The earliest sketches started to suggest this idea of nests—sleeping nests—in the canopy of trees.”
The house’s position on the site underscores this quality. The flat, flag-shaped lot is narrow at the street, widens toward the back, and contains a majestic grove of redwoods on the left near the front and two monumental-scale live oaks on the right, “midway up the flagpole,” David says. He slipped a slender, two-story house between those trees, with interlocking vertical and horizontal volumes and a floor plan that shifts to grab living and viewing zones outside the building envelope. The result is an almost magical house that balances expansive outdoor living with pockets of privacy. Either way, nature is never far away.
Palo Alto takes neighborliness seriously; its planning code called for respecting people’s privacy while also showing evidence of life at the front of the house—no turning your back to the street. “They would encourage a garage in back and living in the front, but this lot was so skinny that it wouldn’t have made sense to do that,” David says. He drew a one-story garage that overlaps the glassy two-story façade behind it and incorporates a sheltered entryway. Zinc detailing ties the garage to the rest of the house, and glass slots emit light to the street.
Both levels of this bar-shaped, steel-and-glass structure are organized along a central spine that runs from front to back on the narrow leg of the lot. The first floor’s kitchen, dining room, and living room are arrayed on one side of the spine facing west into the oak trees. The side yard is an extension of all those spaces—cooking, living, and dining can occur inside or out.
To the left of the corridor are an office, family room, and workout room. Upstairs it is the bedrooms—“floating sleeping pods”—that gaze into the trees, while another study, a laundry, and a master bath line the other side of the hall.
A theme recurs: the blurring of indoor-outdoor boundaries verging on illusion. To the left of the two-story entryway, a glass wall frames the stand of redwood trees. “Once you’re in the house and look back, it’s pretty pronounced as a frame,” David says. “One of my favorite pieces of architecture is the VDL house by Neutra. It was very experimental, and after it burned down and was redesigned it had all these interlocking spaces. He even used reflection, either with water or a mirror, to play a Cubist-like game with the volumes. We tried to create those interlocking spaces so that when you enter the house, there are mirrored surfaces that allow you to see the redwoods behind you.”
Translucent glass in the stairwell and corridors refracts daylight into the center of the roughly north-south-oriented house. The design also makes liberal use of skylights and clerestories, which wash ceilings in light.
With the landscape bracketing the architecture, the material palette was kept simple and modest. The garage volume’s sawn red cedar reappears inside, providing a warm inner liner that resonates with the trees. David used it to wrap some of the walls and ceilings and domesticate the outdoor seating space that extends the living room into the landscape. The living room wall opens on a sliding track, and the ceiling carries the wood beyond that line.
In keeping with their intimate tree house vibe, the second-story bedrooms have oak floors and punched windows that frame views of the leafy canopies, though the master suite opens to a large deck above the back porch. Most of the upper-level walls are white-painted Sheetrock—a canvas for the constantly changing shadows cast by sinewy trees. Downstairs, the concrete flooring has a terrazzo-like finish—an echo of the river rock outside.
That concrete floor turned out well despite the fact that it’s also the structural slab.
“With a bigger budget, we’d do a structural slab reinforced with rebar and then pour the architectural slab over it, which gives us more control over finish and cracking,” David says. “Concrete is such a dynamic material and if not mixed perfectly, poured at the right temperature, and cured at the right speed, it tends to crack—where and how much is the question. We had a contingency plan in case it didn’t go well, but they hit the nail on the head.”
Indeed, every project forces decisions about balancing the budget—especially when surprises like poor soil are unearthed. Construction manager Brian Blackford recalls that the top two feet of soil turned out to be expansive clay. The solution was to use grade beams anchored down to the stable soils—a less expensive alternative to pier construction. “On top of the grade beams was a structural slab, which became the concrete floor,” Brian says. “That floor was ground and polished, and then we had to protect it throughout the entire length of construction. We couldn’t polish it after the walls were up.”
The resources saved by forgoing a second pour were likely diverted to craning in the 7,700-pound cantilevered beam that draws a clean line across the atrium above the living room, supporting the master bedroom and deck. “Contemporary homes are very challenging to build in general because there is no decorative trim to hide variances in ceilings and walls,” Brian adds. “I think it turned out quite well; it was a nice design to execute.”
Going High, Going Low
The lot’s location in a flood plain also informed the design. Lifting the building about 18 inches on a concrete plinth put it above the high-water mark and created an ad-hoc bench that people can sit on outside the main living spaces. A reservoir near the fire pit at the back of the lot absorbs excess water.
As this project shows, site-specific architecture can call out the salient qualities of even a small suburban plot. And a close reading of the landscape can infuse architecture with a lightness it might not otherwise have. For example, the living spaces at the side and back of the house have a horizontal connection to the pool and a vertical relationship to the tree, David says, and lights hanging from the live oak reinforce those physical extensions.
“Privacy is afforded just by virtue of being low in the landscape with things floating above you, and on the upper level by being in the canopy of trees,” David says. “That concept is one I’d like to play with again on another project, but it’s particularly relevant to this site because of the dense suburban context. The goal is that when you walk into the house, you forget where you are—out
of sight, out of mind.”
Palo Alto, California
ARCHITECT: Principals Joshua Aidlin & David Darling; project designer Melinda Turner; project team Kent Chiang, Zac Rockett, Aidlin Darling Design, San Francisco
BUILDER: De Mattei Construction, San Jose, Calif.
LANDSCAPE ARCHITECT: Surface Design, San Francisco
STRUCTURAL ENGINEER: Berkeley Structural Design, Berkeley, Calif.
PROJECT SIZE: 5,870 square feet
SITE SIZE: .30 acre
CONSTRUCTION COST: Withheld
PHOTOGRAPHY: Adam Rouse
COOKTOP AND OVENS: Miele
COUNTERTOPS: Carrara marble, Corian
DOORS AND WINDOWS: Fleetwood
EXTERIOR CLADDING: VMZINC
FAUCETS: Elkay, Waterworks, Hansgrohe
FINISH MATERIALS: stained rough-sawn cedar
GARBAGE DISPOSAL: Insinkerator
HVAC: AO Smith, Taco Comfort Solutions radiant floor system
LIGHTING: Halo, Lutron
PAINTS/STAINS/COATINGS: Benjamin Moore
PHOTOVOLTAICS: Design Build Solar Thermal
SINKS: Blanco, Kohler, Elkay
STRUCTURAL GLASS: West Coast Insulated Glass Products
TOILETS AND TUB: Duravit
VENT HOOD: Arc Zephyr
WINDOW SHADING SYSTEMS: Mecho Shade Slimline