Outback Staked House

A few years ago, while working with the indigenous communities of remote Arnhem Land, in Australia’s Northern Territory, architect Sue Harper became passionate about prefab. She saw local builders struggling with standard on-site construction methods in their efforts to bring housing and public buildings to rural communities—and, in response, started thinking about designs for prefab components that could be easily transported, erected, rearranged, and dismantled. In the late 1990s, Harper and her environmental engineer husband, Andy Irvine, moved back to Sydney, but they vowed one day to return to the far-flung region with a prefab system that would make lighter work of building in the outback.

By coincidence, Harper found herself dusting off those drawings a little sooner than planned—the catalyst was a commission from a young family who wanted to set up a home on Dangar Island, a picturesque parcel of land in the middle of the Hawkesbury River, an hour’s drive north of Sydney. Those planning to build on the island need to be aware of a few things: that the only access is by boat, that the locals don’t like having their peace disturbed, and that the risk of bushfire is high. "The solution had to be lightweight, flexible, fire resistant, and involve minimal time on site and minimal impact
on the environment," explains Harper.

Harper and Irvine first set about designing and building a prototype on their own property, which is on another island, near Dangar Island, and also accessible only by boat (it took about 30 trips in a small motor boat to ferry all the components across). Their plan was to thoroughly test the system before embarking on the Dangar Island commission. "Our prototype was just big enough to allow everything to be tested for strength," says Irvine. "We have a great structural engineer in Max Irvine [no relation], and when he called in to see us, we would tie ropes to it and try to pull it over, jump up and down on it, and shake it, change some bracing around, and try it again. Max is into what we are trying to do and is working on ensuring the structure will be able to withstand cyclonic winds."

The pair’s flexible system consists of modular frames and panels that can be bolted together in countless configurations. A smaller diagonally braced section above each larger frame means that the components are self-bracing. Bolted together, they form a sturdy skeleton that can be filled in with prefabricated, interchangeable panels of almost any material—glass, solid materials, even canvas or palm leaves. For the roof, corrugated-steel panels proved a portable and easy-to-install choice, and for the floor, precut plantation-grown hardwood strips have been used throughout.

"Because the system is self-bracing, it doesn’t rely on the wall material for structural strength," Irvine explains. The panels—uniformly 7.5 by 4 feet to minimize waste—are fabricated off site, and fix onto the frames to create windows, walls, and doors, which can be rearranged or replaced to suit the occupant’s changing needs. "The key aspect of the system is its flexibility," says Irvine. "You can build part of a house and use cheaper materials for the panels, then when time and money allow, you can bolt on more rooms and replace the panels with something better."

Harper conceived of the Dangar Island house as three pavilions joined by suspended walkways, weaving in among tall gum trees (none were sacrificed) and disturbing as little of the undergrowth as possible. The pavilions are elevated on steel posts to capture river views and allow breezes, lizards, and rain runoff to circulate freely underneath. The main pavilion houses the kitchen, living, dining, and deck areas, with three bedrooms and a bathroom below. Glazing to the north means the upper area, particularly, is bathed in winter sun. Covered walkways lead to a separate bathhouse and a painting studio. Harper wanted to create a house that would encourage close contact with the natural surrounds—this home practically insists on it. 

No sooner had the architect-engineer duo finished the design process than the initial clients had a change of plan and decided not to proceed. But Liam Flood, a builder who had worked on many projects with Harper, saw the design, fell in love with the concept and the steep, north-facing site, and decided to take on the project as owner/builder. "For Liam, we needed to create additional spaces, have more substantial walls and openings, and an increased level of finish," says Harper.

Because of the flexibility of the steel-framed panel system, she was able to simply add new rooms—pop-outs as she calls them—onto the original design without making any structural changes. Additional rooms (in this case a larger kitchen, plus laundry, storage, and office areas) needed only to be bolted onto the main structure, and actually "pop out" into the tree canopy.

As with the early prototype, all the building materials had to be taken across to the island by barge (requiring about six trips in all) and physically moved around the site, so the entire project was broken down into portable components weighing no more than 175 pounds that could be carried by two people. "This was the first water-access building job I’d ever done," notes Flood. "It was made all the more challenging by the fact that I don’t like water and I can’t swim! But I’ve worked with Sue and Andy for seven years, and we make a pretty good team. We’re always talking about ways to design buildings so that they can be packed into containers and shipped anywhere in the world."

It was particularly important that the house be assembled as quietly as possible—to keep the peace with the neighbors—so on-site fabrication was kept to a minimum. Apart from the occasional use of a truck (one of the few on the island) and a mini-crane to put up the steel, the builder moved his equipment around the site using, of all things, a wheelbarrow. Despite the difficult access and site considerations, the construction process was swift—just over three months. "One of the great things about Liam is that he can deliver high-quality results in a fast-paced environment," says Irvine. "That’s why he has become so interested in this kind of work."

Harper and Irvine have enjoyed the process of refining their prefab system, and seeing it work so well in its island setting. But for now, they’re turning their attention back to Australia’s far north to further develop their system so that it will work in the harsh outback, providing shelter and community buildings to remote and under-resourced indigenous populations.