Fresh face

Panelised prefab construction was the answer for this Melbourne dwelling on a block with tricky access and mature trees.

Orchard House is a prefabricated dwelling that hits the sweet spot when it comes to design, buildability and performance. But needing to satisfy many competing requirements, it proved a complicated puzzle for design and build operation Arkit to solve. “There were numerous site-based parameters along with the brief,” says architect Andrew Fotia. “The finished house is a narrative of the balancing of all these factors.”

It’s home to medical professionals Jacqueline and Charles, who moved to Australia from Canada with their two young sons. They bought a large block in Alphington, Melbourne, with a ramshackle old house and a dozen mature trees. They decided that the house would go, and be replaced by a thermally comfortable, energy-efficient and airtight home like the ones they had lived in in Canada. The trees, of course, would stay, forming the centrepiece of a new garden by landscape architect Sam Cox.

The couple decided on a prefabricated build for a quicker build time, less waste and higher construction quality. However, their tree-lined street was challenging for access, making a volumetric approach impractical. Instead, Arkit used a panelised method. “The flexibility of panelised construction allowed us to push beyond typical module parameters and design, and to better customise the project to the site, while still achieving the benefits of a prefab process,” says Andrew.

With the first piece of the puzzle solved, the design then addressed Jacqueline and Charles’ brief, which included connection with nature, engagement with the street, and good flow between spaces in a compact house. “We wanted just enough and no more than that,” says Charles. The design also resolved the issues of protection zones for the large trees, the street-facing northern orientation, and the need to provide access to private outdoor space from the living areas.

Clad in fibre cement sheet, the house is built on screw pile footings to simplify construction and minimise disruption to the trees. Arkit constructed the wall, floor and roof components offsite in seven weeks, and simultaneously handled the demolition of the existing house. Once finished, the panelised cassettes were transported on a standard flatbed truck and assembled onsite, with the build completed in a further 25 weeks.

The living pavilion is at the front, where it benefits from the northern aspect and engages with the street. A central courtyard garden just behind has a barbecue, outdoor dining area and a pond to attract local wildlife. This courtyard connects to the rest of the site, where there’s an orchard and chicken coop: “We wanted an urban farm feel,” says Jacqueline.

Inside, the open kitchen and dining area is the primary living space, with tree views in both directions. The kitchen sink under the front window fosters interaction with the street, while a bench seat on the other side of the room offers views across to the children’s playroom. The lounge is a cosy snug; its wide opening continues the flow from the dining and kitchen, and the sliding door and Murphy bed enable it to double as a guest room.

Arkit angled the hallway to negotiate the protection zone of a neighbour’s tree. The main bedroom opens off the hallway and has acoustic insulation to provide an extra-quiet space. The children’s bedrooms and playroom are in the back section of the house, which can be closed off for privacy or noise reduction.

The exposed Victorian ash rafters in the living pavilion, unusual in prefab construction, were possible due to the panelised construction approach. They extend outside, beyond the northern eave that’s tuned for winter sun and summer shade, and meet vertical posts to form a pergola over the front entryway. The central courtyard also features a pergola, which will support deciduous vines for seasonal shading. “As a child, I would do woodworking with my father, and we’d build outdoor structures and furniture. So having these is special to me,” says Charles.

Arkit strategically applied key Passive House principles that resulted in a very good airtightness level of three air changes per hour. “This was achieved using relatively simple, cost-effective measures: well-taped vapour-permeable membranes and thorough draught sealing,” says Andrew. “A mechanical ventilation system provides fresh air without unwanted heat transfer.”

With a desire to be as self-sufficient as possible, Charles and Jacqueline have a 20,000-litre rainwater tank for garden irrigation and toilet flushing, and a greywater diverter for orchard irrigation. The house is all-electric, and solar panels will be installed after assessing a year’s worth of energy use data.

With the complex puzzle solved, Orchard House is a high-performance prefabricated home with a design that goes beyond the constraints of typical volumetric modular construction to complement the nature of the site and the family’s lifestyle.