In a recent interview with MIRVAC, David Haller, National Operations Manager – Masterplanned Communities Construction, shares insight into how their partnership with construction material manufacturer, CSR led to the creation of a new construction and prefabrication methodology, and how the prototype was successfully trialled for a new project which continues to develop and grow.
“We’ve developed an opportunity to be able to further diversify our relationship by using materials from previous engagements and coupling them all together,” he says.
“We’re driven by an aspiration to challenge the boundaries of construction approaches and even the way of thinking in business operations.”
This construction methodology involves a complete wall panel, combining the external cladding of a wall panel (Hebel) with a timber frame, windows, doors, services, insulation and wall lining. These are assembled in a controlled environment, then delivered to and installed onsite.
CSR Velocity is the company that CSR has created to develop these high quality engineered wall and floor elements. The diagram below depicts the wall panel.
In addition to a Hebel masonry cladding, different types of lightweight cladding can also be used in this process to allow Mirvac design flexibility for external facade treatments.
At a time when trade availability is quite low, overcoming significant delivery pressures in current market conditions is crucial.
“If we are able to work offsite by manufacturing wall and floor panels in a factory controlled environment while we’re preparing to start construction, it alleviates a significant amount of potential delay due to trade availability and inclement weather, and allows certainty of delivery,” David observes.
Conventional construction dictates that every separate material is brought to site and put together onsite – be it external cladding or brickwork – and fixed to a structural frame with separate material delivery and individual contractors.
But Mirvac has consolidated all of these components into one location, with all materials in one place offsite and assembled in the factory. The term ‘modular’ often relates to modular buildings or modular units, but in the case of Mirvac and CSR, it is panellised prefabrication.
This concept was first prototyped at a Mirvac project in Elizabeth Hills, Sydney in 2014 and after the successful trial it has been applied on a much larger scale on a new project, which is under way for 300 homes to be constructed at Brighton Lakes in Moorebank. The first stage has already seen 60 homes completed, and the remaining stages are either in construction or due to commence by the end of the year.
“For more simple designs, we’ve reduced construction durations by up to 50 per cent, had a significant reduction in carbon content intensity through lifecycle assessment, improved quality and performance and reduction of health and safety risk onsite,” David notes.
These results are significant, but do not come without challenges related to the design. Simpler designs benefit the most from this form of modular construction, but there have been a number of homes at Brighton Lakes that have not been the most suitable due to their complex nature in relation to layout – particularly with facade treatments.
“When we have balconies and certain articulation in the design that allows the architectural language to be achieved by our design team, those are the sorts of things that don’t necessarily work as efficiently as we would hope for initially.”
“Although we have some issues in relation to efficiency with some of these designs, we’re learning how to adjust them,” he adds.
With 300 homes for this project, many have been slightly adjusted prior to submitting to the local council, to overcome some of the issues identified in the early stages. The idea is not to affect the design to deliver modular prefabrication, but make some compromises and have a broad design delivery for customers.
Some of these adjustments relate to dimensions, overall widths, and step-downs in concrete slabs. That way, Mirvac can eliminate the need for smaller-sized panels that are inefficient.
The savings for more complex designs correlate to about 25 or 30 per cent. The slab stage to lockup stage usually takes about 60 days, but Mirvac is currently completing them in approximately 20 days through the CSR Velocity process.
But this result is dependent on the particular design, and the trade base used to install the Velocity panels. It has been a challenge due to limited trade availability; yet considerable time is still being saved.
“Probably more importantly, the benefits are, from my perspective as a director, the significant improvements in safety. We’ve reduced manual handling significantly, because instead of individual people lifting every timber frame and each individual brick to put it in place, we have cranes lifting up complete panels and putting them in place,” David says.
“We have a significant reduction in the amount of time scaffold remains onsite, reduction in the amount of waste onsite, and introduced the ability to have a site that’s run with fewer people.”
For more information about Modular Construction 2016 download the brochure.
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