Behind the build at Monarto Safari Park

The intersecting curves and earthy tones of the Monarto Safari Park Visitor Centre sit naturally within the South Australian landscape.

Representing the meeting of two worlds, the Monarto Safari Park Visitor Centre’s intersecting circles posed technical challenges that were resolved through the strength and versatility of BlueScope steel walling and roofing.

Spanning 1,500 hectares and home to more than 500 animals, Monarto Safari Park is one of the world’s largest open-range zoos. As the Visitor Centre emerged from the ground, it was likely visible only to the 11 giraffes that call the park home – but the building now appears as though it has always belonged.

Its earthy hues – created through interlocking panel walling made from REDCOR weathering steel and rammed earth – unite with the curved forms of the building’s design. While the landscape may be the Mallee plains of Australia, a similar composition could evoke the Matabo Hills of Africa.

Referencing the connections between these two worlds was a central design driver. This idea is expressed in form – two ribbon-like curves meet and overlap to create a central gathering space – and through contrasting materials used on each arc.

The brief also called for sustainable design features and natural materials to reflect the park’s conservation mission. Early concepts explored using different materials for each C-shape form, but the team ultimately chose steel after collaborative workshops between architects, the construction company and the cladding contractor.

“We had a good hard look at ourselves and just asked, ‘What are we trying to achieve?’” says Terry Boxall, architect and director at Intro Architecture.

“We kept coming back to the desire to have a building that would weather over time – something in this landscape shouldn’t require treatment or maintenance.

“I’d always wanted to use the weathering steel product, so we found the right pan profile and presented to our client, Zoos SA, the fact that it was a product manufactured in Australia and that we wouldn’t have to re-treat it. It ticked all the right boxes and in the end the client loved it too – I couldn’t imagine it being anything else now.”

For project manager David Harris of Mossop Construction + Interiors, the walling made from REDCOR weathering steel delivered further benefits as a product for the client.

“It was quite a significant cost saving,” says Harris. “We were obviously trying to achieve the budget that the client had, and REDCOR weathering steel was one of the ways of doing it while still maintaining the look and feel that the architect was looking for.”

When it came to covering the building’s curved form from above, the architects settled on roofing made from COLORBOND steel in Shale Grey and the profile Fielders FreeForm to accomplish its shape.

The profile’s tapered application minimised the need for flashings – also made from COLORBOND steel in Shale Grey – offering watertightness with minimal material waste.

“When we were first thinking about solutions for the roof, we went straight to Fielders FreeForm. We didn’t go anywhere else because the Fielders FreeForm roofing product is one of the few roofing types that could achieve what we were looking for,” says Boxall.

“Its pans are tapered and obviously the smallest taper in the pan is the tighter arc – and then when there’s a larger arc, it’s tapered out. There were two or three different roof radii, and we spent a fair bit of time working on how those pans were going to come together.”

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To address the finer tolerances associated with the product, it is important to recheck drawings against cutting lists and on-site measurements as the roofing sheets are being laid. This process was made easier with the FreeForm sheets being rollformed at the zoo in batches using a transportable mill.

“Fielders had a 40-foot container that was sent to site… They ran the coil and when they ran it through with a taper, it went through the machine twice on each edge,” says Jarrad Morgan of cladding and roofing contractor, SA Construct.

“Every few panels, they were able to adjust the machine to open or close the taper a bit further. Then they put the panels into packs and craned them onto the roof.”

The roofing made from COLORBOND steel in Shale Grey was chosen as it absorbs less heat than darker colours, an important consideration in the harsh climate of the Mallee plains. Rainwater is also harvested from the roof for reuse in flushing toilets and landscaping irrigation. Swales capture additional runoff for the native plantings in the car park. Other building features include high-performance double-glazed windows, optimal environmental orientation, high-efficiency cooling units and solar energy.

The use of rammed earth provides passive cooling and insulating properties with little or no ongoing maintenance. Steel also supported the construction method, where a soil mix is compacted in formwork to roughly half its original volume. One of the more challenging zones of the build was where generous entryways cut through the rammed earth walls, framed by large steel lintels.

“The cave-like entry portal is a complex piece of geometry – the steel headers are curved in plan and in elevation,” says Boxall. “Everything was modelled in three dimensions architecturally and by the structural steel fabricator. These steel lintels forming the portal opening are also structural, requiring a lot of back-and-forth with the rammed earth contractor and the steel fabricators to achieve the desired aesthetic.”

Joining this effort was Ben Rice, structural engineer at MLEI.

“Any beam that’s on a curve is complex as it goes into bending and into twisting at the same time, so there’s a lot more demand on all the steelwork as a result of the curve, and additional challenges for us to be able to resist some of those loads,” says Rice.

For additional strength, steel columns were embedded into the rammed earth in some areas.

The combination of steel and rammed earth creates a striking arrival point. Boxall described it as a symbolic threshold between animal, human and landscape.

“Entering through the main portal of the building is like discovering a different land… which is signified with the cave-like structure,” says Boxall.

Beyond the portal lies the building’s ‘heart space’ – a communal courtyard designed as a place of calm before the day’s adventure.

“We drew on the concept of a ‘camp’, where there’s a fireplace in the middle, a place to gather, tell stories, and then go off for your day and come back,” says Boxall.

The result is a much-loved new gateway for the park. Visitor numbers are growing, and Intro Architecture and studio gram have since been engaged to design a hotel nearby.

A technical dive into the steel details

The Monarto Safari Park Visitor Centre’s façade – drawing on African and Indigenous references – was designed to feel natural in its surroundings. The deep ochre hues and patina of the walling made from REDCOR weathering steel help it blend into the landscape, while offering additional performance advantages.

Durability and longevity were important to the client. Suited to inland South Australian conditions, REDCOR weathering steel develops a protective patina that tightly adheres to the base steel, resulting in a lower corrosion rate over time compared to conventional structural steels.

Its ability to be formed into 200-millimetre-wide interlocking panels allowed the cladding to deliver the tight curves of the building’s design. At this width, the faceted panels give the appearance of a smooth curve, which was critical to the architect’s vision.

“We bought the 0.7BMT weathering steel coils and slit them to size, then we ran them through a Schlebach Quadro machine [a sheet metal profile shaping system], and that formed them into interlocking panels,” says Morgan.

“Those are cut to length, stop-ended and then installed on the top-hats in a left-to-right fashion. The top-hats were rolled to follow the radius of the wall curve… It was very successful.”

Another detail addressed was the propensity of weathering steel products to transfer oxidised residue to adjacent or underlying materials. At ground level, the wall panels end in troughs of pebble mulch, which is a solution many would be aware of. But with a large, cantilevered section of the walling made from REDCOR weathering steel overhanging the café area, a curved, hidden solution had to be devised for this above-ground wall termination.

“It has a little channel that sits underneath [the panels], almost like a little box gutter…” says David Harris of Mossop Constructions.

The SA Construct team once again put the Pittsburgh lock seam to the test.

“Anything that’s horizontal and following a curve is difficult,” says Morgan. “Every segment is custom because the curvature of the wall might be changing slightly through manual tolerances. Everything’s perfect on a drawing, but the way of construction might mean the radius in certain areas is just fluctuating, so what the curve is to that area has got to be marked out.”

A template was made on-site, taken to the workshop to be cut from steel, and seamed by hand – a manual but effective process.

Despite the challenges, both Morgan and Harris agree the wall panelling made from REDCOR weathering steel was the best solution, offering long-term savings with minimal maintenance.

The panels’ curved appearance is one of many compelling features in a building that brings together different worlds.