The demand on application of advanced engineering in building industry necessitates uninterrupted employment of new engineering work force and geting of latest machinery. A building house would necessitate a immense investing in order to last in acquiring new occupations. Therefore, really frequently, a building undertaking is managed by a general contractor, which sublet the plants out to different subcontractors so that the general contractor can salvage on building cost to vie in monetary value [ 1 ]
Subcontractors are specialist in the executing of a specific occupation, they act as a agents of the production system of the contractor company in providing stuffs, work force, equipment, tools or designs [ 2 ] . Chiang [ 1 ] concludes that farm outing is indispensable to salvage building cost of general contractors to vie on monetary value. Teixeira & A ; Couto [ 3 ] besides agreed that increasing of specialization thorugh subcontracting can help in achieving the undertaking objectives.
When the range of work and logical dependences between subcontractor plants are non to the full understand by general contractor and proprietors, it became a critical job to the success of complex and fast-paced undertakings. Cost judicial proceeding and disgruntled clients due to the struggle between general contractor, subcontractors and other undertaking participants would so followed [ 4 ]
Subcontractor is a common term used in building. Due to the singularity of each building undertaking, the work force is transeunt, multiple trade are involved, each undertakings are planned and worked in short clip frames, and assortment of stuffs and equipments required, one individual building undertaking is frequently sublet to many subcontractors [ 2 ] , [ 5-12 ] . Subcontractors can lend more than 50 % [ 13 ] , and can be every bit much as 90 % of entire undertaking value to a building procedure [ 5 ] .
A building undertaking is awarded to a general contractor or premier contractor or chief contractor or chief contractor, which resorts their work out to specialise outside house to transport out specific undertaking activities. General contractors are responsible for pull offing the undertaking such as contract disposal with clients, undertaking funding, stuff and equipment procuring, and supervising the undertaking advancement [ 14 ] . Harmonizing to Albino & A ; Garavelli [ 13 ] , the general contractor ‘s perfomance are strongly dependent on subcontractors. This statement is reinforced by Mbachu [ 15 ] which stated that the ability of the general contractor and adviser to present the undertaking within clip, quality and cost depends mostly on public presentation of subcontractors.
A subcontractor is a building house that contracts with a general contractor to execute some facet of the general contractor ‘s work. In most building undertakings, a critical function is played by subcontractors who are hired to execute specific undertakings on a undertaking. In the usual instance, the general contractor will execute the basic operations and farm out the balance to assorted forte contractors. Subcontracting is used much more extensively on lodging and edifice building undertakings than on technology and industrial undertakings [ 16 ] .
Types of Subcontractors
Attempts have been meade to distinguish subcontractors. In Hong Kong, Ng et Al. [ 6 ] classified subcontractors to ( i ) equipment-intensive subcontractors ( who are hired due to their specialized works and equipments ) , and ( two ) labour-intensive subcontractors ( those who are hired as a consequence of their specialized labour resources.
Costantino et Al. [ 17 ] revealed that labour-only subcontractor beneficial the subcontractor by cut downing the cost of mobilisation and buying stuff. Furthermore, it besides offers economic advantages to the general contractor by avoiding
Partnering relationship between general contractor and subcontractors were proposed to make a win-win state of affairs [ 5 ] , [ 18 ] . Harmonizing to Lee et Al. [ 18 ] , this long-run relationship must be established to avoid adversarial relationship between general contractor and subcontractor. Several types of relationships between general contractor and subcontractor are discussed, competitory relationships and strategic relationships were among them. Comparison theoretical account based on dealing cost for both general contractor and subcontractor are developed severally for each relationship.
Further subcontracting by subcontractor, or called multilayer subcontracting/latent subcontractor, let the subcontractor to be less vulnerable to fluctuation in concern, have more flexibleness in work force coordination, and be able to cut down cost of direction [ 7 ] .
In Turkish, pattern of farm outing work by subcontractors to secondary subcontractor is widespread [ 19 ] . A survey on 35 general contractors and 56 subcontractor organisations revealed that most of them are willing to sublease their work under overload of work or clip force per unit area.
When “ latent ” subcontractor happened, the extent of subcontracting is even larger. “ Latent ” subcontracting, or multilayer subcontracting is the farther farm outing down the watercourse by subcontractors with or without the cognition or consent of the general contractor or client. This has been alleged to be one of the major causes of hapless building quality and building site safety in Hong Kong [ 1 ] , [ 7 ] . Ekstrom et Al. [ 20 ] argues that payment to the 2nd grade subcontractor/suppliers can be portion of the public presentation measuring when measuring subcontractor.
Problems of Subcontracting
Ability to pass on and organize the work of subcontractors has been identified as one of the chief conceptual determiners of building undertaking direction competency in China [ 21 ] .
Subcontractor failure has been listed as one of the hazard allocated to general contractor in building contracts [ 22 ] . This is supported by El-Sayegh [ 23 ] which stated that subcontracting is hazardous and can take to low quality, delayed completion and insecure pattern. Another hazard created by subcontractor is the possibility of them to transgress contract and difference with the general contractor. Hence, subcontracting has been listed as one of the important factors doing hold United Arab Emirates [ 24 ] , [ 25 ] and Malaysia [ 26 ] , [ 27 ] .
PERTINENT STUDIES ON SUBCONTRACTOR
Focus of research workers goes to either finding the components of farm outing or developing new approaches/techniques to choose and/or manage subcontractors. Subcontractor has become an issue on its ain, separated from selection/management of general contractor by client/consultants due to its complexness. Numerous subcontractor choice and monitoring theoretical account has been proposed [ 4 ] , [ 13 ] , [ 28-30 ] .
Choice of Subcontractor
Many choice methods of subcontractors has been proposed in the literature. Arslan et Al. [ 28 ] developed a web-based subcontractor rating system ( WEBSES ) to ease the choice of subcontractors. The standards for measuring was identified by calculators of building house in USA based on a database of about 4000 subcontractor houses.
Ng & A ; Luu [ 31 ] developed a theoretical account for subcontractor enrollment determination through case-based logical thinking attack. 12 experts were interviewed to supply indispensable stairss needed for distinguishing good and bad subcontractors. The theoretical account developed use each properties ‘ calculated evaluations for designation of fiting instances and similarity mark of each single instances. The historical information of subcontrators can be retrieved and utilize for the current rating. Weighting of all atributes can be easy modified harmonizing to the users penchant, therefore the effectivity of this theoretical account is still really much depends on the experience and cognition of users.
Manoharan [ 32 ] proposed a subcontractor choice method utilizing Analytic Hierarchy Process ( AHP ) based on 29 questionnaires collected from contractors involved in building undertakings located at Putrajaya, Malaysia. It is an Adept System to help the chief contractors in doing their determination by utilizing pairwise comparing. The determination shaper will necessitate to do their ain opinion on the comparative importance of each component with regard to the elements at a higher degree. Argument might happen when the opinion of different determination shapers are diverse.
As an attempt to cut down the incidents of hold, and other possible jobs that might be originated from the jobs of choosing the incorrect sub-contractor, this survey aims to spread out the sample of survey as suggested by Manoharan [ 32 ] in the attempt of create an more dependable and applicable sub-contractor choice theoretical account.
Management of Subcontractor
Choosing the right subcontractor does non vouch the success of a building undertaking. Coordination and monitoring of subcontracted work during the building phase is indispensable. Ko et Al. [ 33 ] developed a Sub-contractors Performance Evaluation Model ( SPEM ) by using Evolutionary Fuzzy Neural Inference Model ( EFNIM ) . Subcontractors were evaluated by field overseers harmonizing to the types of subcontract. Different rating factors were adopted for different subcontract to accomplish just rating.
Albino & A ; Garavelli [ 13 ] proposed a evaluation system for direction of subcontractor by utilizing nervous web. An application instance related to the rating of possible subcontractors viing for a command has been used to demo the practical execution of this nervous web. In accessing the rival subcontractors, the determination shaper have to see five chief parametric quantities, viz. monetary value decrease, clip decrease, technical/qualitative feature of the command, contractual dependability of the rival, and direction accomplishments of the rival. The web will suggest a suited subcontractor based on old determinations made by the expert. Therefore, illustrations of old determinations need the expert to be inserted into this nervous web.
Dainty et Al. [ 34 ] focused on supply concatenation ‘s direction from the position of subcontractor. The function of subcontractors in UK building industry is explored and followed by proposal of a model for turn toing current barriers to provide concatenation integrating.
Subcontractor has become a great topic to all the practicians in building industry due to the common pattern of subleasing building works into smaller bundles in building industry. Effective subcontractor choice and monitoring which can minimise the job would find the success of building companies.
Problems of subcontractors, if ignored, can do an huge impact to the building undertaking, and can widen into the operation of the general contractor ‘s administration. Therefore, attending shall be given to the issues of subcontractor, which is the chief participant in about all the building undertakings.