Advanced manufacturing processes and just-in-time delivery are just some of the developments that have changed the prefab industry. Increased adoption of digital tools, along with design for manufacture and assembly (DfMA) principles, will further enhance prefab’s value proposition.
The rise of new digital industrial technology, known as Industry 4.0, is a transformation that makes it possible to gather and analyze data across machines, enabling faster, more flexible, and more efficient processes to produce higher-quality goods at reduced costs.
Prefab and its associated advanced manufacturing processes are quietly changing the face of building and construction, and helping to unlock a range of benefits and new efficiencies. High-quality, energy-efficient and aesthetically pleasing buildings, delivered in demonstrably faster, safer, and more productive and environmentally sustainable ways, at increasingly lower costs. Prefab is estimated to account for less than 5% of Australia’s 150 billion building and construction industry. Sweden (84%), The Netherlands (20%) and Japan (15%).
What is prefab?
Prefab is short for prefabrication. It refers to any part of a building that has been fabricated somewhere other than its final location. Prefab is also referred to as off-site fabrication, off-site construction or off-site manufacture.
Prefab complements traditional construction and comes in all shapes and sizes, from components such as wall frames, roof trusses and insulated wall panels to modular construction elements, pods and complete buildings. Prefab usually uses timber, concrete, metal or plastic, or a combination of these materials.
2D and 3D are the two main families of prefab systems. These systems can be used on their own, with each other to create hybrids, or in conjunction with traditional construction approaches. The possibilities are incredibly diverse
2D prefab components are pre-cut, pre-sized, pre-moulded or pre-shaped elements that are assembled or installed on site.
Panelised, or non-volumetric, systems may make up the building envelope, stair cores, internal load-bearing walls or lighter partitions. They may be open or closed panel systems, precast concrete panels or other panel types, including CLT. And each one is created through a range of advanced off-site manufacturing technologies.
These 2D elements may be structural, architectural or services elements, or a hybrid of these.
Modular, sectional, volumetric or unitized systems are three-dimensional structural units that are combined on site with other units or systems. It is also possible to create an entire building from one system.
In general, pods are used for bathrooms or kitchens rather than as structural modules.
3D prefab has a number of key advantages. It is a fast way to build, as the modules can be manufactured while the site is being prepared. Individual modules can be joined to create larger spaces. And modular systems can be used in high-rise environments.
Some manufacturers are vertically integrated with in-house design, engineering, project management and installation teams, while others choose to work with dedicated partners throughout the building and construction supply chain.
Lean and advanced off-site manufacturing processes are considerably faster than the equivalent building process on site. This is due to the enclosed and controlled factory environment, the ability to coordinate and repeat activities, and higher levels of automation. Manufacturing can take place in parallel with foundation work, unlike the linear timeline of a traditional project. Australian prefab and modular home manufacturer, Faster construction times can lead to faster occupation, generating income for clients earlier and lowering site overheads as less time is spent on site.
These factors, together with fewer weather disruptions and reduced defects and rework, can help reduce construction times by 20–60%.
Health and safety is easier to control in a factory. In conventional construction, there are several safety issues, including working at height, congestion and weather-related workplace accidents.
In addition, well-planned off-site logistics can dramatically reduce the number of necessary vehicle movements, improving safety at and around the site. It is estimated that workplace health and safety incidents could be reduced by as much as 80% by using off-site
Minimum site disturbance, tightly managed material flow and construction waste, and pre-planned assembly and disassembly can significantly reduce the environmental impact of construction. Factories can be optimized to achieve waste levels below 1%, in comparison with waste levels of between 18% and 22% for traditional construction .
Studies have shown that prefab modular construction can reduce landfill by at least 70% produce up to 50% less CO operating emissions due to improved thermal efficiency.
A predetermined level of quality can be achieved in a factory-controlled process. In addition, the indoor environment means buildings and components are protected from climate extremes and vandalism.
Quality control is much easier and better in a factory environment than on a construction site, which has a
big impact on rework. Reducing or eliminating rework significantly improves construction schedules, potentially by up to several months. There is also the risk of defects not being identified on site until many months or years later, when they are far harder and more expensive to rectify.
In the context of an ageing construction workforce and skilled worker shortages, prefab manufacturing supply chains should be designed in a way that appeals to a younger and more diverse workforce. Minimizing the need to work in all weather conditions and using technology to reduce physical and administrative tasks could encourage more people to join the construction workforce.
A factory process should be inherently more productive than
a site task. A UK study found that productivity could increase from 30% to 80% in a well-managed off-site factory, which can deliver cost savings.
In the right environment and with certain trade-offs, prefab can cut costs by 20%. This level of savings is perhaps more the exception than the norm today. However, there is some evidence to suggest that prefab may be able to reduce costs by more than 20% based on what has been achieved in some mature markets.
Prefab offers greater cost certainty as it has fewer weather delays and an earlier design freeze compared to traditional construction.
With the right skills and training initiatives, prefab can help create a more productive on-site construction environment.