Often, the best design emerges from the strictest of constraints. This three-storey house by Studio Wills + Architects is an excellent example and a testament to the architect’s deft hands. Sitting on the highest point of the Adelphi Park Estate in Singapore’s central area, the home’s 6,199sqft plot enjoys a sweeping view of its low-rise landed neighbourhood and the distant Central Catchment Nature Reserve.

However, the elevated plot also has a 7.5m road buffer setback, imposed by the local planning authorities, along the length of the site, which considerably limits its buildable footprint into a narrow trapezoid with a tapered point.

Adding to this constraint was the clients’ extensive programmatic brief. Housing a family of four with occasional visits from the grandparents, its must-haves included a living and dining area served by a kitchen and back-of-the-house facilities, a family room, three bedrooms with ensuite bathrooms, one master suite and two home offices/study areas. Other requirements were a sheltered carpark for six cars, an entertainment room that fits a pool table, a bar and home theatre. These had to be arranged to maximise the view of the estate and nature reserve.

The massing of the house stretches over the entire length of the site to regain the areas lost to the setback. Spaces that do not require daylight and views – service areas, carpark, and entertainment room – are placed on the basement level, which is not limited by the setback. On the ground floor, the setback area itself is occupied by a lawn and a garden that flank the driveway to the basement. The rest of the spaces are arranged within three storeys articulated with three contrasting materials.

“The design had to accommodate the client’s wish for mid-century modern aesthetics, including a diverse palette of materials, such as off-form concrete, bricks, steel and timber, which they are fond of,” shares William Ng, Founder and Principal Architect of Studio Wills + Architects, who helmed the project.

“However, the most challenging aspect of the project remained to be the need to satisfy the clients’ penchant for rectilinear blocks in a trapezoidal site and right-sizing the building for a site that had little buildable areas due to the severe building setback requirements.”

The clients’ fondness of the mid-century modern’s diverse material palette was a boon to Ng’s design, which responded to the brief with a tripartite arrangement of stacked boxes affectionately dubbed the Glass Box, Concrete Box and Steel Box. Together, they gave the house its name, the Trio Stack.

On the ground level is the Glass Box, containing the living and dining areas, the kitchen, and the guest bedroom, all of which enjoy visual access to the garden on all sides, thanks to its glazed walls. An entrance patio, a long-stretching veranda and a shaded cosy outdoor sitting area mediate the inside and outside.

Above this level is the Concrete Box, which contains the two children’s bedrooms, the wife’s study and the family room. Its concrete facade is stretched out to wrap around the perimeter of the buildable area, creating an impression of a larger building. Seen from the front, the Concrete Box looks rectilinear, but both of its side elevations reveal folded corners – one features a viewing window for the study, and the other hovers above the outdoor room on the ground level, forming a band around its single Caesalpinia ferrea tree and shielding the Glass Box from the harsh tropical sun.

Commonly known as the leopard tree or Brazilian ironwood, the tree nicely fills out the negative space wrapped by the concrete band. “We were not involved in the selection of plants, but we did suggest that there should be a single tree in that space, and that it should have delicate and filigree-like branches to complement the Concrete Box,” explains Ng.

Crowning the house is the Steel Box. “It’s more aluminium than steel, actually,” he quips. “But the reference as steel alludes to its lightness.” Resting lightly above the solidness of the Concrete Box, this pavilion-like box contains the master suite and the husband’s study, each featuring an outdoor terrace overlooking the Central Catchment Nature Reserve.

A single pier finished with black bricks containing the vertical circulation binds the trio of boxes together. The material was chosen for its visual weight, which creates an impression of the entire building being held together and secured by a single anchoring vertical element. “It also complements the metal elements such as fenestrations, screens, railing and coping which were powder-coated black for visual uniformity,” adds Ng.

Asked about which part of the design he is most proud of, he shares about the curated materials. “We embraced the diverse material palette and elements the clients were fond of and approached the selection, application and detailing in a way that ensured that the entire palette remains cohesive, subdued and restrained to avoid what could potentially be a visually ‘busy’ design.”

An example of this is the selection of the concrete. “The client had originally wanted off-form concrete walls, but we proposed 65mm-wide board-form ribbed concrete walls to match the chosen bricks. The concrete walls are further stepped in the section for textural effect and to mimic the brick courses,” he says.

The house’s balanced interplay of visual opaqueness and porosity, and harmonious material palette, is further enhanced by incorporating elements that are meaningful to the clients. One of them is the window louvres, which they use in their house in Malaysia, he explains, “They found this to be a climatic-responsive device to address their need for a well-shaded and well-ventilated interior without reliance on mechanical ventilation.”

For homeowners, it’s the little things like this that turn a house into a home.