Hutchinson Builders has topped out the "first-of-its-kind" full merging of two separate commercial buildings in Brisbane’s $700 million Midtown Centre.
Mining giant Rio Tinto signed a 10-year lease deal in 2019 on the 27-storey, Fender Katsalidis-designed tower, developed by AM Brisbane CBD Investment, a joint venture between wealth manager Ashe Morgan and developer David Mann’s DMann Corporation.
The project involves the $175 million connection and refurbishment of the former Health and Forestry Buildings located at 155 Charlotte Street and 150 Mary Street—acquired in 2017 for $66 million—into a cross-block hub comprising a commercial tower, with a public laneway connecting both streets.
Rather than using the conventional method of joining the existing 20-storey buildings by a skybridge, the buildings have been merged from top to bottom using a base podium and exterior, to provide large campus-style 2,500sq m floor plates.
The infill is locked in by a new level 20 slab supporting an additional six levels above, to form the single 26-storey tower currently being constructed by Hutchinson Builders—who, like other "essential services" have continued work while adapting to Covid-19 social distancing measures.
Fender Katsalidis director Mark Curzon said the infill completion is a huge accomplishment in terms of commercial design outcomes, adaptive reuse and sustainability in Australia.
"Through good design, we have given new life to the buildings in a somewhat unconventional but highly innovative and technically considered manner.
“We're leading the way for more environmentally-friendly adaptive reuse while meeting commercial objectives in creating large floorplates that would otherwise be unattainable in this CBD location,” Curzon said.
Compared with a demolish and rebuild scenario, Midtown Centre’s infill achieves a claimed 231 per cent cumulative impact reduction across all environmental indicators, including a 37 per cent carbon dioxide reduction compared to a new build.
Curzon said that although the successful merging of the structures in the Midtown development rests partly on the fact that the two buildings’ original designs mirror each other, the technique was transferable.
“The infill has afforded significant environmental savings, adding to the viability of this technique and its potential to be implemented across other buildings that sit side-by-side.”
Fender Katsalidis principal James Mills said the project sets a new standard for the repurposing of buildings.
“Despite nothing of this scale or nature taking place in Australia previously, we have found a way to add value to the site through a cutting-edge architectural process that is exemplar for Brisbane and beyond.
“Our work at Midtown Centre is focused on bringing the buildings in line with today’s needs, increasing net lettable area and producing environmental sustainability through the design of commercial assets,” Mills said.
Even before coronavirus created the new normal of social distancing, which in turn is set to have transformative impact on office design—Ashe Morgan chairman Michael Moss predicted the "customised office solution" prescribed for Rio Tinto would "create a benchmark for workplaces of the future".
The centre features a level 20 "sky garden", landscaped garden terrace atop the podium and "green seam" encasing the tower along with landscaped areas across the development totalling in excess of 3,000sq m.
With the Midtown centre slated for completion in mid-2021, the next phase of construction involves the addition of six levels to create a single tower from the new level 20 slab.