15-02-2013, 04:47 PM
Prefabricated Building Construction Systems Adopted in Hong Kong
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Abstract:
Prefabricated building construction systems have been widely adopted not only in public houses but also in private building projects. Prefabrication together with the increasing use of standardisation and mechanisation has brought a substantial change in the development of the construction industry worldwide over last few decades. Though the development and use of prefabrication in building construction comes a bit late for Hong Kong, the drastic increase in the application of this technology in building projects in the recent years does regain certain momentum in this leaving-behind area. Besides the accompanying of the related advancements to the local construction industry with the adoption of more mechanisation, computer aided manufacturing, and intelligent management systems, the extensive use of prefabrication also contributes to sustainable development by using cleaner and more resources saving production process.
Introduction
Prefabrication has been used extensively and widely for many years around world. Pre-assembly, prefabrication, modularisation, system building and industrialised buildings are the terms which have been frequently used to describe that the manufacture of building components are constructed either on-site or off-site in a factory covering manufactured, modular and pre-cut or pre-engineered systems. Although the terms, are often interchangeably used, their precise definitions depend heavily on the users’ experience and understanding, which vary from countries to countries. In this paper, prefabrication is preferred with special emphasis on the building components are made off-site in a factory. Off-site fabrication is a topic of international interest and provides an effective construction technique in terms of quality, time, cost, function, productivity and safety. It is adopted worldwide as the ideal means of producing an immense array of elements from structural members, cladding units, and bathrooms to fully-finished modular buildings.
As many prefabrication technologies deliver a better product because building is done in a quality controlled, sheltered environment, the move to more prefabrication in construction industry is inevitable. It is seen as one of the tenets of improving construction in the 21st century (Egan, 1998; Yeung, Chan and Chan, 2002). This is also echoed by Raysford (2000), “a much greater emphasis on off-site assembly was one of the key ingredients to changing the construction culture to retain and recruit talent and at the same time deliver improvements in performance required by increasingly demanding clients.” This paper is cantered on how prefabricated building systems have been adopted in Hong Kong.
Development of Prefabricated Building Construction in Hong Kong
It is recommended that prefabrication together with the extensive use of standardisation and modularization should become essential principles in the design and construction of high-rise residential buildings in Hong Kong in this century (Yeung and et al, 2002). The need to provide affordable, sustainable and functionally competent housing is fundamental to the living standards and well being of individuals and families throughout the World (Howes, 2002). The Hong Kong Special Administrative Region (SAR) government is no exception (Hong Kong Housing Authority (HKHA), 2000; Construction Industry Review Committee (CIRC, 2001). Hong Kong is a small island with scare flat land for building development. There has been a long history of housing shortage. Most of the buildings are dominated by high-rise design.
In the race to meet the extremely tight construction schedule in the Hong Kong construction industry, a trend toward prefabricated construction has set the tone for design. Besides, there is an urgent need for increasing the number of low cost apartments for public housing blocks to help the lower income population. According to the HKHA report (2000), more than 30 percent of population (about 2 millions) in Hong Kong is living in public housing (HKHA, 2000).
Application of Prefabrication Technology in Hong Kong
It is well-recognized that HKHA is the pioneer in the introduction of prefabricated technology to mass-productive housing in Hong Kong. Being the major developer and landlord, the HKHA has made significant influence on the design and construction of buildings, leading the local construction industry from building traditionally towards the era of rationalization (Wong and Yau, 1999).
Despite a few trial projects being executed in the early 1970s’, the first project making use of significant amount of prefabrication by the HKHA could be dated back to the late 1980’s, in which the façade, stair flight, floor slab (semi-slab) or minor beam were precast in the design. The first generation of precast elements (Figure 4) showed quite a number of problems, especially for the fix-in type façade, where water leakage was very common coming from the window frame which is installed in-situ onto the openings, and the joints between the façade and the structural walls (Figure 5). The second generation of façade was very much improved. This was done by the casting of the window frame together with the façade unit during the concreting process (Figure 6), as well as the façades are cast at the same time with the surrounding in-situ structural walls (Figure 7).
Conclusion Remarks
In general, the use of prefabricated building construction system can be described as a success experience in Hong Kong. This system has been widely adopted and commonly used in public housing development projects, which are characterised by its great degree of repetitiveness and mass production. After more than 10 years application and accumulated experienced, practitioners in the construction industry hold the general view that prefabricated construction represents reliable, quality and cost-saving means to construct. However, successful implementation of the system still depends on the industry’s ability to drift effectively toward a more professional and rationalized structure, as well as the seeking of more opportunity to apply the technique broadly and to a wider range of projects such that the construction system can be perfected. The further enhancement on procurement and supply-chain relationships for prefabrication appears to be an inevitable trend.