Words by Tony Whitehead
Melbourne contractor Hickory’s 44-storey tower was completed in just 16 months
Speeding up the construction process with prefabricated buildings
You don’t have to be an engineer to see that the residential tower on La Trobe Street in Melbourne demonstrates two key qualities that prefabricated building has traditionally struggled to provide. For one, it is 44 storeys high, and for another it is distinctive, featuring a keyboard-inspired facade that belies the methodology behind its construction. Its fashionably skinny form accommodates 206 apartments rising from a 360m2 floorplate and, remarkably, locally based contractor Hickory has taken just 16 months to build it.
“I would guess it would take more like 26 months if we were using traditional construction methods,” says Hickory’s co-founder and joint managing director George Argyrou. “Our system costs the same, so by completing early our client saves money because they get a faster return on investment.”
Benefits of the Hickory system
Hickory’s system varies from project to project, but essentially comprises hot-rolled steel box frames incorporating an engineered concrete floor. At La Trobe Tower these boxes came in varying sizes of up to 4.2m x 16.4m, with pre-fitted bathroom pods and a pre-attached facade. “The module size is one of the first things we have to decide, and it’s determined by logistics,” says Argyrou. “What size load can we transport to site on local roads? What crane can we use? It might need to lift up to 22 tonnes.”
These constraints are then turned over to Hickory’s structural engineers who are now well practised at designing buildings the Hickory way. They know, for example, that the modules are manufactured, and located, to 1mm tolerances. Even so, with a building of this height, one might expect inaccuracies to build up and settlement to occur. So how does the system cope? “We know it will settle, say, 30mm over 30 levels. And with our system, the interface has a tolerance — you can adjust the stitch joint. In fact, La Trobe ended up just out by 6mm — less than what the engineers’ models had predicted. Going higher is no problem and we are currently looking at 60-floor projects.”
So what kind of benefits has the Hickory system delivered at La Trobe Tower? “One key thing is, because the floors are part of the off-site manufacturing process, you decouple pouring concrete floors from the critical path,” says Argyrou. “That meant we were able to do two floors a week at La Trobe. Four floors a week should be possible.”
He adds that because the modules are factory-engineered, the quality is high and reliable, and because facades can be pre-fitted, there is no live edge to the building. “It really is cleaner, safer and quicker.”
It is also quieter — a feature of modular construction that has, in one unexpected way, led to Hickory being a victim of its own success. At a previous project in Melbourne, deliveries of modules were complicated by the presence of trams. Because these do not run at night, Hickory was allowed a trial period of night working, despite fears that it would disturb neighbouring residents. In the event, the process proved so quiet that on its next project — in a tram-free area — the company has been encouraged to work at night in order to decrease the effect of site traffic during the day.
Limitations to the Hickory system
If it all sounds too good to be true, then Argyrou does at least concede that the system will not work everywhere all the time. Location of the factory, for example, is key and a lot of Hickory’s work is close by in the Melbourne area. (When Hickory took its approach to Perth, 5,000km away, it trained up a local contractor to make the modules.) “The local market, local costs and site conditions also determine what sort of project is suitable,” says Argyrou. “In Melbourne it begins to make sense at around 30 storeys.”
It is worth noting too that Hickory’s modules are not of the fully-finished variety — rather they are room-sized, or even apartment-sized, structural elements with certain features attached. Neither do they incorporate much in the way of mechanical and electrical fitting. “We see no speed advantage to doing that in the factory,” says Argyrou.
Maybe this is why Hickory is enjoying success where others have struggled. It knows exactly what it wants from off-site fabrication and is careful not to over-complicate the process.