We would like to clarify some misconceptions on prefabrication shared in an earlier letter ("Prefab construction not so productive; 12 November 2014").
Firstly, prefabrication involves manufacturing building components such as walls, columns, beams, and even entire bathrooms and room-sized apartments in factories before they are installed on site. It enables faster construction as various trades can be done concurrently in the factory and on site, thus making site progress less affected by the weather. With a better quality control regime in the factory, prefabricated components have better quality and therefore less rework is expected.
To achieve a quantum leap in productivity, the Building and Construction Authority (BCA) is working with the industry to adopt the Design for Manufacturing and Assembly (DfMA) approach, by moving as much construction work as possible off site to a controlled and automated manufacturing environment. Many advanced countries such as those in Europe as well as Japan and Australia are using more prefabrication and DfMA to reduce manpower requirements and improve construction productivity.
Secondly, we should compare the productivity of different construction methods in terms of physical output such as area constructed per manday. BCA has been tracking and monitoring the productivity of various construction trades for many years.
An example is the use of dry wall, a prefabricated product, which can be installed much faster on site and requires 65% less manpower compared to traditional plastered brick wall. Besides time and manpower savings, dry wall construction generates less construction waste, debris and dust.
Thirdly, we wish to clarify that all construction workers in Singapore, including those for prefab construction, are not unskilled. All new construction workers are required to pass a skill certification test conducted by BCA before entering Singapore as basic skilled workers. Precast and dry wall installation are trades that are recognised through these skills certification tests. BCA will continue to work with the industry to build up the expertise of these skilled workers through continuing education and training to support the industry's drive towards a higher level of productivity.
BCA acknowledges that prefabrication requires land. Hence, we have been working with various agencies and the industry to develop higher density, multi-storey Integrated Construction and Precast Hubs (ICPHs) that will optimise land usage for prefabrication. ICPHs are highly automated, have at least twice the production capacity compared to open precast yards with the same land sizes, and can be energy efficient. To date, one such factory is operational and two others are currently under construction.
It is also important that builders and manufacturers plan, co-ordinate and manage the just-in-time delivery and installation of prefabricated components to reduce storage space required for prefabricated components. To enable designers, contractors and precasters to improve their capability in planning and managing projects, the BCA Academy has been conducting training courses on precast design and management. Other courses on Building Information Modelling (BIM), productive technologies and construction management also help the industry push for higher construction productivity.
Ang Lian Aik
Group Director, Construction Productivity Centre
Building and Construction Authority