Marcela Carranza Arquitectura Lifts a Single-Level Home for Elderly Owners above a Steep Costa Rican Slope

Steep sites usually invite one of two responses: cut the hill into terraces, or stack the house down the slope in a cascade of half-levels and stairs. Marcela Carranza Arquitectura takes a third route with House in the Air in San Mateo de Alajuela, Costa Rica. The 268 m² home, completed in 2023 and led by Marcela Carranza Vargas with Juan Carlos Sotela and Jorge Cordero, is lifted off the ground on slender posts. The hillside keeps running underneath it.

What makes this more than a dramatic structural gesture is who the house is for. The owners are elderly, and the brief asked for a home that would stay accessible and comfortable as they age. A stilted house on a steep lot sounds like it would work against that. Here the elevation does the opposite: it lets the entire program sit on one continuous floor plate, so the slope is solved by the structure and not by the people living above it. We think that inversion is the real story.

Touching the Hill as Little as Possible

The architects describe their approach as minimal intrusion, and the photographs make the idea legible. The house reads as a long timber volume held up by thin steel columns, with grass, boulders and an old mango tree left in place below. Only a dark plinth wall marks where the building actually meets the ground at its uphill end.

The environmental logic is direct. Raising the house cuts down on earthwork, keeps ecological continuity beneath the floor, and lets rainwater run off the slope along its natural paths instead of being redirected around foundations. On a tropical hillside with heavy seasonal rain, preventing flooding by not damming the slope is a smarter move than engineering drainage after the fact.

A Lantern on Stilts

In low evening sun and at dusk, the house changes character. The glazing that dominates the downhill faces turns the volume into a lit box hovering over dark rock, and the steel posts nearly disappear. The sloping roof and the curved, cantilevered deck give the composition its silhouette, so it reads more as a pavilion than as a conventional suburban house.

There is a risk in this much glass on an exposed slope, both thermally and in terms of privacy. The deep roof overhang and the dense surrounding canopy seem to be doing much of the work of moderating that, though the available information does not detail any passive climate strategy, so we would treat that reading as visual rather than confirmed.

The Deck Is the Main Room

If one space defines daily life here, it is the covered deck. Exposed timber beams carry over from the interior, black pendants hang above a long dining table, and the view opens straight across to forested mountains. It is set up for eating, hosting and lingering, which fits the project's later name, Casa Tertulia, a nod to unhurried conversation.

The deck also follows a curve along the edge of the house, and that curve matters. It softens the transition from the rectilinear volume to the landscape and produces a long, continuous outdoor promenade at floor level. For older residents, a level outdoor room reachable without a single step is worth more than any garden down the slope.

Edges That Invite You to Stay

Sliding glass walls fold the living room into the deck at the corner, erasing the threshold. Steel railings, some with fine cables, keep the edge transparent so the view stays uninterrupted from a seated position, which is a detail that pays off precisely for people who spend more time sitting than standing.

The hammock is a small but telling inclusion. It signals that the deck is meant to be inhabited for hours, not just crossed on the way to the view.

Living Under Exposed Timber

Inside, the living, dining and lounge areas share one open volume beneath exposed timber rafters. Woven pendant lamps, pale wood furniture and a white sofa keep the palette quiet, letting the structure and the tree reflections in the glass carry the atmosphere. The roof pitch gives the shared space more height than the private rooms, a simple way to rank the spaces without changing floor levels.

The open plan is also practical for accessibility. Fewer doors, wide sightlines and furniture arranged loosely in one room make movement easier, whether with a cane, a walker or simply slower steps.

Private Rooms Facing the Canopy

The private side of the house is calmer and more enclosed. A timber-clad corridor with a round mirror and a floating console leads toward the deck, and the bedroom opens through black-framed glass doors, carrying the timber ceiling and rattan pendants from the public rooms. The kitchen, with pale wood cabinets and a dark counter, looks directly into leafy canopy; being lifted puts you at branch height rather than at root level.

The bathrooms continue the material discipline: stone basins, slate flooring, open shelving and a slatted ceiling. Forest light reaching the vanity keeps these rooms from feeling like service spaces. We would have liked more information on accessibility details such as grab bars or step-free showers, which the photographs do not clearly show.

Plans and Drawings

The drawings confirm the central idea. The floor plan shows a single level, with bedrooms and bathrooms lined up along the west side and an open living area spilling onto an L-shaped deck. The section is the clearest diagram of the project: a pitched-roof house on thin posts, with the ground falling away beneath it.

The elevations reveal the structural strategy in more detail. Cross-braced steel supports handle lateral loads on the downhill side, while the west elevation shows the house almost meeting the ground, its row of framed windows sitting under a low roof. That uphill side is likely where the level entry happens, and it explains how a stilted house can still be reached without stairs.

Why This Project Matters

House in the Air shows that lifting a building is not only an ecological gesture or a way to grab a view. Used carefully, it is a tool for accessibility. By letting the structure absorb the slope, Marcela Carranza Arquitectura gives elderly owners a single, level home on a site that would normally demand stairs everywhere. That is a lesson many hillside houses, especially those built for retirement, could absorb.

It also makes a quiet case for restraint in landscapes that are easy to damage. Less grading, uninterrupted runoff and an undisturbed ground plane are modest ambitions compared to sculptural form, yet they shape how the house feels to live in. The result is a home that sits lightly on its hill and serves its residents well as they age.

House in the Air (Casa Tertulia) by Marcela Carranza Arquitectura, San Mateo de Alajuela, Costa Rica. Area: 268 m². Completed: 2023. Photography: Andres Garcia Lachner.

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