Estudio Diagonal Terraces a Red Steel Refuge into a Chilean Rainforest Hillside

Most hillside houses treat slope as a problem. The architect flattens, excavates, retaining-walls the grade into submission, then plants a house on the newly horizontal slab. Estudio Diagonal, led by Sebastián Armijo Oyarzún, took the opposite position with Casa La Ladera in Puyehue, Chile. The steep incline above Lake Puyehue is not a constraint to be neutralized; it is the organizing principle of the entire plan. Two gabled volumes, clad in red corrugated metal, step down the hillside at staggered heights, each elevated on stilts to leave the forest floor almost untouched.

What makes the project genuinely interesting is how that two-volume split maps onto a domestic program for three generations. One volume, tied to the arrival point higher on the slope, holds communal life: kitchen, dining, living room. The second drops lower and contains the private rooms: bedrooms, bathrooms, a secondary sitting room. Between them, a planted courtyard acts as both a hinge and a pressure valve, letting grandparents, parents, and children share a house without sharing every moment. At 220 square meters, the house is generous but not sprawling, and its compactness keeps it legible against the dense canopy of native hualle trees.

Red in the Green

Red corrugated metal is a deliberately confrontational material choice in a temperate rainforest. It reads industrial, agricultural, even utilitarian, and that is precisely the point. The house does not pretend to dissolve into its setting. Against a wall of deciduous hualle trunks and deep green understory, the crimson cladding announces human presence without apology. The visual contrast sharpens the boundary between architecture and forest, which paradoxically makes the surrounding landscape feel more present, more wild, more itself.

Elevating the volumes on steel stilts reinforces this logic of separation. The ground plane flows beneath the house uninterrupted. Roots stay intact. Drainage patterns hold. The building hovers over the slope rather than sitting on it, a tactic that reduces earthwork and keeps the structural footprint small. It is both an ecological strategy and an aesthetic one: the gap between floor and grade makes the house appear lighter than its corrugated shell would suggest.

The Courtyard as Social Hinge

The planted courtyard between the two volumes is the most spatially sophisticated move in the project. It transforms a narrow gap between buildings into an outdoor room that feels sheltered without being enclosed. Red walls rise on two sides, native planting fills the ground, and daylight drops straight in from above. For a house designed to hold two families at once, this intermediate space is critical. It creates a threshold where you can see across to the other volume without being forced to engage. Privacy becomes a matter of position, not closed doors.

Inside, the courtyard functions as a light well. The atrium space that opens onto it receives a tall wall of glazing, pulling diffuse forest light deep into the plan. The sloped timber ceiling amplifies the height, giving a room that could feel compressed by its corrugated exterior an unexpected airiness. A staircase facing the courtyard doubles as informal seating, an in-between perch that belongs neither fully indoors nor out.

Timber Interiors, Warmth Against the Rain

If the exterior is assertive, the interior is generous. Exposed timber beams and planked ceilings wrap the communal spaces in warm, tactile surfaces. White walls below the timber ceiling keep the rooms from feeling cabin-dark, and corner glazing pulls the forest canopy into the living area at eye level. The material palette is restrained to the point of severity: timber, white plaster, black steel framing. Nothing competes with the view.

The kitchen and dining area occupy the social heart of the communal volume. A black island anchors the kitchen, while a timber stair climbs along a fully glazed wall, layering vertical circulation against the trunks outside. Designed as a year-round refuge in southern Chile's demanding climate, the interiors need to perform in both the long, wet winters and bright summers. The heavy timber ceiling structure absorbs and radiates heat slowly, a passive strategy that keeps the rooms comfortable without requiring complex mechanical systems.

Private Rooms and the Forest Edge

The private volume steps lower on the hillside, and its bedrooms open through black-framed glass doors onto railed balconies that cantilever into the canopy. The experience is intimate: you wake up level with the treetops, looking through deciduous branches toward the lake. A covered timber deck on the building's edge extends the private realm outdoors, its vertical wood cladding and steel railing defining a secondary exterior room sheltered from rain.

Detailing at the junction of materials is careful and deliberate. Vertical timber cladding meets metal fascia in clean lines, and the elevated steel railing reads as furniture rather than structure. These joints matter because they are visible from every balcony and deck; sloppy connections would undermine the precision the house relies on to hold its own against a chaotic forest backdrop.

Reading the Slope from Above

The aerial view reveals how tightly the gabled roofs cluster together, their angular forms echoing the irregular rhythm of the surrounding treetops. From above, the red metal reads as a geological event, a seam of color exposed on the slope. The roofscape is not monolithic; ridgelines shift and break, reflecting the internal split between communal and private volumes. That fragmentation keeps the house from reading as a single mass dropped onto the hillside, and instead presents it as a series of smaller interventions stitched together by the courtyard.

Plans and Drawings

The site plan makes the topographic logic legible: contour lines compress tightly across the slope, and the building footprint is oriented perpendicular to the grade, threading between existing trees. The ground floor plan shows the two rectangular volumes connected at a narrow point, with the courtyard wedged between them. Rooms stack along the short axis of each volume, keeping corridors minimal and circulation tight.

The section drawing is the most revealing. It shows how the pitched roofs respond to the slope, rising and falling to maintain headroom while the floor plates step down. The stilts are visible beneath, their varying heights absorbing the grade change without any cut-and-fill. Four elevations document the house from every cardinal direction, and in each one the forest trees are drawn at the same scale as the building, a useful reminder that the house is, by design, subordinate to its context.

Why This Project Matters

Casa La Ladera is a quiet argument against two common tendencies in vacation-house architecture. The first is the reflexive desire to hide a building in its landscape through camouflage: green roofs, mirrored glass, earth tones. Estudio Diagonal opts for visibility, and in doing so gives the forest permission to be wild rather than scenic. The second tendency is the open-plan cult of togetherness, the assumption that a family house should be one big room. By splitting program across two volumes, the design acknowledges that families are not monolithic, and that proximity and privacy can coexist if the architecture provides the right thresholds.

The project also demonstrates that building on a steep slope does not require heroic engineering or environmental sacrifice. The stilts, the compact footprint, the minimal site disturbance: these are straightforward tactics executed well. At 220 square meters, the house proves that a multigenerational retreat does not need to be enormous; it needs to be organized. That organizational clarity, rooted in the slope itself, is what gives Casa La Ladera its coherence and its staying power.

Casa La Ladera by Estudio Diagonal (lead architect: Sebastián Armijo Oyarzún), Puyehue, Chile. 220 m², completed 2021.

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