What’s new in prefabrication
Many developments have been made in timber frame prefabrication systems, particularly in terms of design software. Kevin Ezard provides an update on the latest news from the sector.
The recent Frame Australia 2012 conference in Melbourne created an opportunity for the latest global trends in timber frame prefabrication and engineered wood construction systems to be discussed, with many developments of interest presented to the building industry during the two-day event.
A major breakthrough in design software for timber wall frame and roof truss prefabrication was announced by MiTek with the unveiling of their new generation software program Sapphire™. This ‘whole of house’ program creates a single model for the building that includes the entire structure, overcoming the current problem of multiple software programs required for the design of floor, wall and roof components.
This enables the MiTek fabricator to determine what’s needed to make a structure work and overcome ‘buildability’ issues that often arise, such as correcting plan dimensions and roof lines that don’t work. In addition, other products such as bracing, floor beams and other structural components can be incorporated into the software to generate a complete model of the house frame.
Having all the various building elements in one package also makes it easier to communicate with owners, architects, engineers or the builder as to how something needs to be built and how it will look.
The MiTek Sapphire software was recently introduced into the US market and is now underway with Australian fabricators.
In Europe and Australia the topic of building prefabrication has now become more popular with developers and builders, for common reasons of the increasing costs for building on-site and the length of time required for construction.
While detached housing is not as significantly influenced by this at present, it has become a critical issue for multi-residential buildings with designers and builders seeking alternate methods of construction.
A major property developer and builder told the conference that incorporating timber prefabrication had actually improved their earnings from construction of medium density housing.
The improvement had been achieved by a number of initiatives, starting with efficient building design which had reduced construction cost per square metre by up to 20% through refining the designs and improving documentation using multi-disciplinary consultancies and Building Information Modelling (BIM) data.
Incorporating prefabrication or off-site manufacturing (OSM) in the form of panelised floor, walls and roof being lifted in by crane actually increased construction costs by about 4% but enabled construction time to be reduced from 18 months down to just 10 months.
This significant reduction in time meant the increase in financial return from the project went from 11-17% after inclusion of the 4% increase for construction cost. And a bonus for the company was the improvement in safety on-site, with much safer working conditions for the reduced amount of building labour required.
While this is still an emerging trend in medium density housing of three to four storeys, the long-term projection is for much more prefabrication to be undertaken to enable builders to meet the objective of reduced labour on-site. But at the same time it must be at a lower overall cost which has now been demonstrated as achievable by developers in local and international buildings.
For another example, in the last issue of Building Connection I referred to Australia’s first timber high rise apartment building and the tallest in the world, ‘Forte’ in Victoria Harbour at Melbourne’s Docklands, which is being built with prefabricated panels of Cross Laminated Timber (CLT).
This is the first building in the country using a timber prefabrication system for construction of 10 storeys, and project designer and developer Lend Lease has stated that it will be built 30% faster than with other materials (see page 20).
If you would like to see Forte actually being built on live webcam, go to www.forteliving.com.au for a bird’s eye view of construction, which is proceeding at over a floor completed every week with a site labour force of only four carpenters.
Lend Lease said that prefabricated CLT panels “will transform the construction industry by introducing a more efficient and environmentally friendly construction process that has never been undertaken in Australia before.”
They also commented “the company is aiming to develop 30-50% of its apartment pipeline using CLT and sees application elsewhere across the Lend Lease group.”
This surely points the way ahead for timber prefabrication to undertake a much more important role as a construction system for residential buildings in the future.
And as Sean O’Malley of environment organisation Planet Ark said in his presentation to Frame Australia, “wood is a low environment impact option for building – it stores carbon, it has a lower embodied energy than other building materials and it is renewable” – so from his viewpoint that’s also good for the world.