Frugal & flexible

This Perth residence combines prefab efficiency with flexible dual occupancy, all on a budget.

When Ben Caine set out to design his own family home in Perth, he wasn’t chasing showpiece architecture. Instead, affordability, efficiency and adaptability drove every decision. Prefabrication played a key role in keeping the project achievable for the architect and director of Leanhaus. “It had to be something that could be executed cost-effectively, but also quickly,” he explains.

The result is an 8.8-Star, all-electric home built for many different scenarios. A self-contained apartment within the footprint provides rental income now, and, down the track, options for multigenerational living, ageing in place or household change.

Financial constraints shaped the project from the start. After the Banking Royal Commission tightened borrowing capacity around the country, Ben had to scale back. “All of a sudden we went from being able to borrow say a million dollars, to more like $600,000,” he recalls. The budget forced him to rethink size and form. The answer was a single-storey, 235-square-metre home – apartment included – arranged as a compact square.

The square footprint maximises internal floor area in relation to the external walls. In practice, this means getting more usable space with less building material, and reducing both construction costs and heat loss. It also set the project up perfectly for prefabrication, with wall and roof frames produced offsite as simple, repeatable modules. “We had a very repetitive shape, a very repetitive roofline,” Ben says. “It was one of the easiest architect-designed homes the prefab company had ever done.” All the wall frames and the roof went up in less than a week. “It was very quick, and speed equals cost savings.”

Rather than splurging on finishes, Ben channelled the budget into performance. Deeper-than-standard 170-millimetre timber frames allowed for R5 insulation in the walls. “The greatest improvement you can make to the performance of a home is in the density and thickness of the insulation you install, because it slows down the passage of heat,” he says. Delaying heat transfer means the house stays comfortable, even during Perth’s hot summers.

Although uncertified, the home has levels of airtightness and insulation that match Passive House standards, and the family’s lived experience is proof. In winter, they’ve never needed to turn on the reverse-cycle air conditioner. The family also parted with piles of heavy clothing and bedding. “We got rid of all our winter house clothing such as slippers and hoodies, and our thick doonas. We just don’t need it all anymore,” Ben says. “Even on the coldest mornings, we’re walking barefoot in summer clothes, completely oblivious to the outside temperature.”

In summer, the modest six-kilowatt air conditioner quietly maintains comfort at low capacity, powered by the home’s rooftop solar. Ben describes it as “barely even blowing” while holding the home at 23 to 24 degrees Celsius, regardless of how hot it gets outside.

Material selections followed the same lean ethos. Durable, low-cost Colorbond clads the sun-exposed east and west walls, while naturally finished timber defines the shaded entries and outdoor living spaces, “where you appreciate it the most,” says Ben. The timber is shaded for durability, protected from the sun and the weather.

The home’s design flexibility stands out. The self-contained apartment occupies a quarter of the footprint, complete with its own entry. For Ben and his family, it provides rental income today and long-term adaptability. “It currently covers three quarters of the mortgage,” he says. “You’re not giving up a lot to get a lot back.”

The apartment is nearly always occupied, with tenants ranging from doctors on local placements to grandparents visiting family. Because it’s attached to the main house, it counts as ‘hosted’ short-term accommodation under Western Australian rules, avoiding the strict limits placed on unhosted rentals. And when the extra income is less necessary, the space can evolve with the household: it could be a studio for adult children, a downsized dwelling for Ben and his wife Sophia in later years, or even his architectural office.

Keeping both dwellings under one roof also reduces costs by sharing services such as hot water, solar electricity and mechanical ventilation with heat recovery. “It is quite cost-efficient, compared with a separate structure in the backyard,” Ben says.

With – usually – seven occupants across the main home and apartment, the house averages just over 30 square metres per person. For Ben, that density is more important than raw floor area. “I don’t think it necessarily comes down to the size of the house. I think it’s more about how you accommodate more people in the space that you have,” he says.

True to his practice’s name, Leanhaus, Ben has stripped the project down to what matters. “I just wanted to edit out the fluff and focus on the good stuff,” he says.