Building cost comparison between conventional and formwork system: a case study of four-storey school buildings in Malaysia

American Journal of Applied Sciences, April, 2005 by Nuzul Azam Haron, Ir. Salihuddin Kadir Hassim, Mohd. Razali Abd., Mohd Saleh Jaafar

Abstract: The Malaysian construction industry is undergoing a transitional change from an industry employing conventional technology to a more systematic and mechanized system. This new system is now known as the Industrialized Building System (IBS). This new method of construction can increase productivity and quality of work through the use of better construction machinery, equipment, materials and extensive pre-project planning. This study becomes very necessary since there is yet no organized body, which can provide the necessary information on the building cost comparison between the conventional system and industrialized building system in Malaysia's construction industry. This study also addresses the building cost comparison of the conventional system and industrialized building system of formwork system. It provides the details building cost between the conventional system and the formwork system and indicates which of the two is cheaper. The data were collected through questionnaire survey and case study, which consisting of institutional buildings. Through the statistical test 't-test' it is shown that there is a significant difference in cost saving for the conventional system as compared to the formwork system (industrialized building system)

Key words: Conventional, Formwork System, Building Cost, Comparison

INTRODUCTION

The Malaysian construction industry is undergoing a transitional change from an industry employing conventional technologies to a more systematic and mechanized system employing the latest computer and communication technologies. This is vital for the future health of the industry, given the trend towards global competition and the advent of the k-economy.

The Industrialized Building System (IBS) has been introduced in Malaysia since the 60's by the use of precast concrete beam-column elements. Since the demand of building construction has increased rapidly, it is necessary to innovate a construction method, which speeds up the building construction process. Abdullah et ad. [1] has listed the various types of building systems currently available in Malaysia. Few definitions of industrialized building system are also given by various authors [2]. To sum-up, in general, the IBS is a methodology whereby a local construction industry is driven towards the adoption of an integrated and encouraging key players in the construction industry to produce and utilize pre-fabricated and mass production of the building at their work sites. This will help to enhance the efficiency of construction process, allowing a higher productivity, quality, time and cost saving.

The construction cost of a building using precast components should be assessed in its overall context. The traditional method of costing by material quantities with a fixed factor for labor cost can lead to incorrect estimation. For example, if labor usage is halved, this will more than compensate for a 10% material increase. More importantly, there is saving in time. Also, if properly designed and executed, precast can lead to much better quality of work. The overall cost impact of precast has therefore to take all these factors into consideration. With the rising costs of labor and less assurance of dependable skilled manpower, the trend is that precast construction will become increasingly competitive compared to cast-in-place construction [3].

Classification of Industrialized Building System Industrialization: The Oxford English Dictionary (1991) defines industrialization as "the process of industrializing or fact of being industrialized; also, the conversion of an organization into an industry". However, industrialization in this study means industrial methods employed, referring to especially, prefabrication, mechanization and standardization. The meaning of prefabricated, according to the same dictionary, is, "to manufacture, sections of building or similar structure, in a factory or yard prior to their assembly on a site". However, prefabrication in this study is the assembly of buildings or their components at a location other than the building site.

The types of construction methods range from a conventional construction method to fully prefabricated construction method. Generally, the construction methods are classified here into four categories:

* Conventional construction method

* Cast-in-situ

* Composite method

* Fully pre-fabricated method.

Conventional Construction Method: Conventional building method is defined as components of the building that are pre-fabricated on site through the processes or timber or plywood formwork installation, steel reinforcement and cast in-situ. Conventional building are, mostly built of reinforced concrete frames [4]. The traditional construction method uses wooden formwork. It is much more costly for construction, which includes labor, raw material, transportation and low speed of construction time [5].

Cast-in-situ Construction Method: This system is suitable for a country where unskilled labor is limited. There is no heavy machinery or high technology involved. The system is technically applicable to almost all types of building. Formwork is used as a mould, where wet concrete, is poured into a temporary system. The temporary system also acts as a temporary support for the structures. The objective of in-situ method is to eliminate and to reduce the traditional site based trades like traditional timber formwork, brickwork, plastering and to reduce labor content. A carefully planned in-situ work can maximize the productivity, speed and accuracy of prefabricated construction. Cast in-situ method uses lightweight prefabricated formwork made of steel/fiberglass/aluminum that is easily erected and dismantled. The steel reinforcement is placed within the formwork as they are being erected and concrete is poured into the mould. When the concrete is set according to the required strength the mould are dismantled. The workers can be trained easily to erect the moulds and set the steel reinforcement. Its advantages over the traditional construction method are, its low skill requirement, can be quickly constructed, maintenance is low, structure is durable and cost can be less [5].