Lowering timber floors in a 19th-century building required a flexible propping solution using a hydraulic sync system
In Newcastle, Richard Crookes Constructions (RCC) is constructing a new urban village in the city’s east. Due for completion in late 2021, the project includes refurbishing a heritage building that dates to the 1890s and once housed a David Jones department store.
In May 2020, the construction firm engaged Coates Engineering Solutions to design and install propping, together with a synchronous hydraulic jacking system, to lower three floor levels in the heritage building. The 12-port jacking system allows large heavy structures to be lowered or lifted in small increments synchronously.
Due to heritage constraints, the existing timber floor structures had to be maintained, rather than replaced with structural steel. This meant they were much more flexible than reinforced concrete or structural steel, which allowed for more differential movement.
Each of the 370sqm timber floors needed to be lowered between 1,150mm to 2,750mm. Once the floors were cut away from the walls, they were essentially floating and supported by the props and the hydraulic jacking system.
Once each floor was lowered, new structural steel columns had to be installed sequentially and the floor tied back into the existing brick façade before any props could be removed. “Some of the columns previously removed from the building had to be located and reclaimed from a vineyard in the Hunter Valley, and reinstated as part of the redevelopment,” says Patrick Barry, Project Manager at RCC.
The Coates team included Temporary Works Engineer Darren Browne; Design Manager Abu Zachariah, who designed the propping and jacking system; and Engineering Manager Neil Gujare, who managed the installation. “Because it was a complicated, high-risk job, the client trusted us to deal with the design and installation,” says Neil.
“Not everyone knows we have a technical design team and an install team, so we can provide solutions from start to finish,” adds Darren. “Our site engineers do the certifications and sign-offs for the customer and are independent of the design and the install. We also offer third party certification – all under the same PO.”
Initially, the team used Coates’ proprietary Universal Prop System, a heavy-duty modular propping system that is pre-certified and compliant with all Australian Standards and is easily bolted together on-site. The props were monitored via a wireless telemetry system so both Coates and Northrop, consulting engineers for the permanent works, could verify the loads remotely by mobile or laptop.
While the Universal Prop System worked well, the team decided to adapt the design for the next floor level.
“Synchronously lowering the floor by 250mm and then modifying the props, lowering by 250mm and then modifying the props and so on, was more time intensive than anticipated,” says Neil. “For the second level, we included light-duty tilt props and titan props with set heights to speed up the process, which in turn saved the client money.”
The Sydney-based team also stayed in Newcastle during the job. “We were on site from 7am to 3pm or until the job was finished, so there was no mobilisation which saved time for the client,” says Neil.
RCC originally considered two options to lower the floors: disassembling and rebuilding the floors at a new level, or hydraulically lowering them. “Using the hydraulic method with Coates was about 45% cheaper and 50% faster, so it was definitely the right option,” says Patrick.
The firm also valued working with one supplier to design, supply, install and certify the propping and jacking system, says Patrick. “Every element that Coates did was perfect,” he says. “It would’ve been a lot harder had we split it up into multiple packages.”
“I use Coates on a quite a regular basis for all our general hire items and site accommodation,” Patrick continues. “But if temporary works such as propping heavy structures or load shifting are coming up, Coates will definitely be a frontrunner again.”
Need temporary works for your next project? Call Coates Engineering Solutions on (02) 8796 5000
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