Performance comparison between structural element of building systems in Malaysia

American Journal of Applied Sciences, May, 2005 by M.R. Abdul Kadir, W.P. Lee, M.S. Jaafar, S.M. Sapuan, A.A.A. Ali

Abstract: The Industrialised Building System (IBS) was introduced in Malaysia in 1966, but it failed to establish itself on a continuous basis though there is a sustained large market for residential projects even since. One of the reasons behind this shortcoming is the lack of scientific data on labour productivity that could convince policy maker. Hence, the objective of this study is develop a standardised data collection methodology for measuring and comparing the conventional building system and IBS in term of labour productivity, crew size and cycle time. Labour productivity (manhours/[m.sup.2]) is defined as the manhours required to complete the structural element of one unit house. A total of 499 data points were obtained from seven residential projects constructed between January 2003 and April 2004. Analysis of Variance (ANOVA) indicated that the labour productivity was significantly different between four structural building systems. The mean labour productivity for conventional building system was 4.20 manhours/[m.sup.2] followed by cast in-situ table form (2.70 manhours/[m.sup.2]), cast in-situ half tunnel form (1.88 manhours/[m.sup.2]) and precast concrete system (1.33 manhours/[m.sup.2]). Further, the analysis of crew size indicated that the mean crew size for conventional building system of 24 workers was significantly different from the IBS of 22 workers. However, the crew size within the IBS was found to be insignificant. The cycle time measured in days per house was found to be significantly different between structural building systems with the conventional building system of 4.9 days, cast in-situ table form of 3.9 days, cast in-situ half tunnel form of 2.9 days and precast concrete system of 2.3 days. The labour productivity obtained from this study could be used as a preliminary guideline for client or consultant to identify the most appropriate building system for executing a construction project and determining the labour requirement in the construction industry.

Keywords: Labour Productivity, Crew Size, Cycle Time, Industrialised Building System, Residential Project

INTRODUCTION

Construction labour productivity represents one of the core elements in construction industry. Its paramount applications include construction planning, scheduling, cost estimating, accounting and cost control. Indeed, [1] labour productivity rates are used to generate international labour factors and also suggested ways in which they could subsequently be applied to determine comparative international construction cost and labour requirement.

Many researchers have conducted the study on labour productivity for construction industry. Nevertheless, the majority of them concentrated on labour intensive conventional construction system. Little attention is devoted to perplexing question such as productivity measurement for industrialised building systems (IBS) despite the proliferation of the systems in Malaysia. The growth of these IBSs are attributed to the need for huge demand for housing industry during the Eighth Malaysia Plan (2001-2005) whereby 600,000 to 800,000 houses are expected to be built.

The conventional construction system which is presently being used by the construction industry is unable to cope with the demand in a stipulated period. The method is labour intensive and rely heavily on foreign workers. Thus, productivity research attention shall be devised toward IBS which employs the philosophy of assembly activity. There is an immense potential for productivity improvement in building industry from craft activity to assembly activity as depicted in Table 1 [2].

Malaysia's Experience in IBS: The idea of using industrialised building system in Malaysia was first mooted during the early sixties when the Minister of Housing and Local Government visited several European countries and evaluated their building systems performance. Then, in 1964, the government took a brave decision to try two pilot projects using IBS concept. The first pilot project consisted of 7 blocks of 17 storey flats and 4 blocks of 4-storey flats comprising about 3,000 units of low cost flats and 40 storey shop lots. The project was awarded to the Gammon/Larsen Nielsen using the Danish System of large panel industrialised prefabricated systems. Meanwhile, the second pilot project was built in Pulau Pinang with the construction of 6 blocks of 17 storey flats and 3 blocks of 18 storey flats comprising 3,699 units and 66 shop lots along Jalan Rifle Range. The project was awarded to Hochtief/Chee Seng using the French Estiot System [3].

With reference to the two pilot projects, a performance comparison between the IBS and conventional building system has been carried out in terms of cost, productivity and quality. It was discovered that the first pilot project incurred 8.1% higher cost than a similar building using conventional building system, while the second project was 2.6% lower. In term of construction speed, both projects required 27 months to complete, inclusive of time required to set up the precasting factories. The quality of building finishes was also found to be better than the conventional building system. In conclusion, the overall performance of an IBS is competitive with the conventional building system. Since then, the use of IBS is more profound with the participation of private and public sectors such as Housing Research Centre in Universiti Putra Malaysia aimed at promoting and developing novel building system.