IDIN Architects Keeps a Retirement House on the Ground and Lifts Its Pool Toward the Khao Yai Hills

Retirement houses usually get designed as if the owners have already stopped moving: one storey, wide doors, nothing ambitious. IDIN Architects take a more interesting position with CN House, a 956 m² residence in Nai Mueang, in the Khao Yai area of Nakhon Ratchasima. The family commissioning it is entering its retirement years and wants to live here for the long term. The brief names universal design, simplicity and natural ventilation as priorities. All three show up in the plan. What the brief does not ask for is a timid house, and IDIN does not give them one.

The key move is a vertical split. Everything needed for daily life, including the bedrooms and a semi-outdoor living area, sits on the ground floor, so the owners never have to climb stairs to sleep, cook or sit outside. The second floor is a social level built around a guest lounge and the main swimming pool, raised to catch the mountain panorama. Daily life stays level. Pleasure, guests and the view go upstairs. On a long, narrow plot running from the public road to the foothills, that split also gives the house its shape: a heavy stone base under a light timber and glass crown.

A Stone Base Under a Timber Crown

From the road, the house reads as two materials doing two jobs. River stone and rubble walls anchor the ground floor and hold the edges of the deep site. Above them, a shingled pitched roof and timber-lined soffits sit low and wide, closer to a sheltering hat than a second storey. The front facade has a broad gable that reads as a single generous gesture. It does not announce a large house.

The aerial views show how the massing steps down to the lawn and settles into the trees. The roofs break into several pieces rather than one continuous lid, which keeps the 956 m² from looking bulky against the forested hills. We think the scale control is one of the project's quieter strengths. You get a substantial family house that still looks like it belongs to the slope.

The Semi-Outdoor Room as the Real Living Room

Folding slatted timber doors are the most useful device on the ground floor. Opened, they turn a covered sitting pavilion into a terrace that runs into the lawn and the reflecting pool. Closed, they filter light and keep air moving while giving some privacy. IDIN says this semi-outdoor area is designed to maximise airflow, and in a hot, humid climate that matters more than any amount of glazing.

Stone walls flank the pavilion, so the space feels sheltered on two sides and open on the others. It is a simple arrangement, and it suits ageing residents well: a level threshold, shade, a breeze and a view of water. You can spend most of a day here without deciding whether you are inside or out.

Sending the Pool Upstairs

Putting the main pool on the second floor is the decision that defines CN House. At ground level, a pool on this site would face lawn and hedges. Lifted, it lines up with the hills, and the long rectangle of water extends the horizon toward the forest. A glazed slot in the roof above the lap pool lets daylight onto the water while the timber soffit frames the view like a lens.

A translucent canopy on steel beams covers part of the pool terrace and leads into the glazed living room. It is a more industrial note than the rest of the house, but it earns its place by giving shade without darkening the deck. At dusk, the steel bench, glass balustrade and pebble roof edge make the terrace read as an outdoor room for guests. That is exactly the social role the plan gives this level.

An Upper Room Built Around the View

Inside, the pitched timber ceilings carry the roof form straight into the rooms. The upper lounge faces floor-to-ceiling glass and green hills, with a ceiling fan doing the work an air conditioner might do elsewhere. The living and dining hall opens to treetops, so the room feels lifted into the canopy rather than perched above it.

The material palette stays restrained: timber overhead, glass on the long sides, very little ornament. That restraint is the point. On a site with views like these, the interior's job is to frame the landscape and not compete with it, and these rooms do that without fuss.

Stone Brought Indoors

The rubble stone of the exterior walls carries into the kitchen and living area as a feature wall. Oak cabinetry and open shelving sit in front of it, and the contrast between rough stone and fine joinery gives the space warmth without clutter. Teak lounge chairs and a ribbed round table keep the furniture in the same tactile register.

A slatted timber panel door set into a pebble-faced wall shows the same idea at a smaller scale. The house keeps returning to two materials, stone and wood, and lets the junction between them carry the detailing. The approach is economical, and it will age well.

Stairs, Bridges and Bedrooms at Grade

The floating stair, with lit treads rising between two rough stone walls toward a glazed opening, is the most dramatic interior moment. It is also optional by design. Because the bedrooms sit on the ground floor, the stair is a route to the social level, not a daily requirement. That is universal design handled through planning rather than through grab rails and ramps alone.

An elevated timber walkway with metal railings crosses a planted garden beside the cantilevered upper volume, adding a second route through the landscape. The bedrooms open through full-height sliding glass onto timber decks, broad-leaved palms and the lawn. Waking up and stepping straight outside, with no level change, is a real gift to people planning to grow old in a house.

Water, Walls and the Evening Light

A long stone wall runs beside a still reflecting pool toward the glazed pavilion, and at dusk the composition doubles in the water. Uplights wash the stone, grass lights mark the paths, and the timber-lined balcony glows above. The landscape, by Landscape Tectonix Limited, keeps the planting loose around these hard edges, which stops the water and walls from feeling too formal.

These views show how much of the house's character comes from its walls. The stone does more than clad a building. It runs out into the garden, defines courts and holds the water, organising the narrow site into a sequence of outdoor rooms.

Plans and Drawings

The ground floor plan shows two bars linked by a central living area, with parking, bedrooms and service rooms set among existing trees. The second floor plan stacks a central living and dining zone above, with the long rectangular pool, terraces and roof decks extending outward. Read together, they make the vertical split plain: private and practical below, social and scenic above.

The sections cut through the pitched roof, the pool level, the stair and a basement, and they show how the low stone walls give way to the taller central volume. The elevations confirm the logic you sense on site: a stone plinth carrying a tiled roof and a glazed upper floor, framed throughout by trees.

Why This Project Matters

Housing for older residents is becoming one of the most important briefs in residential architecture, and too often it produces houses that feel like accommodation. CN House shows another route. Put everything essential on one accessible level, then give the second floor to delight: a pool, a lounge and a view worth climbing for. The owners can use it whenever they want, and the house never requires them to.

The project also makes the case for passive comfort as a core part of designing for long-term living. Slatted shutters, semi-outdoor rooms, ceiling fans and deep timber soffits are low-tech tools, but they let residents stay connected to air, light and landscape as their routines slow down. For a practice whose name stands for Integrating Design Into Nature, that is a credible statement of intent.

CN House by IDIN Architects, Nai Mueang, Thailand. Area: 956 m². Completed: 2025. Landscape: Landscape Tectonix Limited. Photography: DOF Sky | Ground.

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