Putting the pieces together with DfMA

Design for Manufacture and Assembly (DfMA) may be a new term for some, but it’s the way Northrop’s been primarily working for a long time.

So, what exactly is DfMA and what are the benefits of working this way? 

Traditionally, most construction jobs have been completed primarily with site-based labor. Everything happens in a logical order and one part begins when the previous one has been completed.

Today, however, things are different and, at Northrop, it’s been our standard practice for a number of years to do as much as possible off-site, delivering components to the site when they’re ready and when they’re needed. 

“There are a number of reasons for this,” says Rob Winbank, Northrop Principal and Structural Engineer.

“Ultimately, it’s a safer, quicker and more economical way to approach a job. It also minimises the margin for error and provides more assurances in regards to costs.”

The key benefits of DfMA

Time

“Traditionally, while the foundations and the civil services were being constructed on-site, nothing else could happen,” says Rob.

“However, working off-site enables us to work in parallel with the ongoing construction program, providing a huge time-saving.

“If you can carry out the civil work on-site while at the same time fabricating things like walls, floors and columns off-site, you’re gaining real efficiencies.

There’s also significant savings in propping, formwork and other temporary works, when each element is delivered to site as required and erected in their final position.”

The alternative, of course, is to carry out all work on-site. However, when you consider waiting for the civil services to be installed, the footings to be cast and inspected, the ground floor slab to go in, not to mention the falsework, it’s easy to see how much more time-efficient DfMA is. And then there’s the weather!

Safety

And it’s not just the time taken to complete the construction that’s important.

Health and safety is paramount for everyone on-site, and a reduced construction program means less time on-site – meaning less opportunity for accidents to occur. The use of assembly and less construction on site reduces the number of people required on a site, also improving safety in worksites known to be congested with trades. In the new COVID environment, this makes social distancing much easier to achieve on site.

“There’s not a month goes by when you read about a formwork collapse in Australia,” says Rob. “Working this way helps reduce the use of formwork and that in turn helps from a safety perspective.”

Quality control

By fabricating individual components in a controlled environment, you can reduce the variables that impact quality.

Measurements can be checked in the yard – a surveyor on-site can measure the real environment and then relay that information back.

“We can inspect all of the components before they even see the site. And if it’s not the right quality it gets rejected.”

“When casting concrete on-site, many variables including the temperature being too high, can result in it being poorly compacted or having gone off too hard or too soon. Remediation work will then be required.”

Climate action

We now know that reducing construction time on site can also lower the carbon emissions during the delivery phase, which is valuable for contractors who are now increasingly being asked to measure and reduce embodied carbon in their works.

DfMA also lends itself to timber components which we love because timber soaks up and locks away carbon. The more we use, the more we stimulate sustainable forestry and carbon drawdown.

Alongside the quality control that in-factory construction gives us is the reduced wastage of materials through precision assembly and streamlined inventory control. With around 30% of landfill waste in Australia coming from the construction industry, DfMA can deliver waste reductions of up to 90% for a project. With the growing focus on circular economy principles, projects that really drive down materials wastage will be winning on a number of fronts. Reduction of site theft is another bonus.

And given our growing body of work in the climate risk advisory space we know that a warming climate means a reduction in days on site due to high temperatures, so the shift towards offsite assembly is already written in the science.

An added bonus

Another benefit of a compacted construction timeline is, of course, that sites can be operational in significantly shorter periods of time. And that makes a financial impact in two ways.

“Working in this way can reduce the timeline by up to 60%,” says Rob. “Builders operate at huge fixed costs every day for running a site, so reducing the project timeline certainly provides benefits.”

Additionally, however, it means constructions can be operational significantly earlier than would have been previously – and whether you’re building a hospital or school, university or shopping centre, that can result in some serious additional income.

Contributor(s)
PRINCIPAL, STRUCTURAL ENGINEER
Author(s): 
Robert Winbank

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