77 Navorsingsartikels • Research articles A post-contract project analysis of material waste and cost overrun on construction sites in Abuja, Nigeria Peer reviewed and revised Abstract Material waste and cost overrun have been identified as common problems in the construction industry. These problems occur at both pre- and post-contract stages of a construction project. As a result of a dearth of empirical research and low level of awareness, the majority of managers of construction projects in Nigeria pay hardly any attention to material waste issues that affect cost overrun. This article examines the material waste issues that affect cost overruns at the post-contract stage of building projects. The study covers building construction projects in Abuja, Nigeria. In-depth interviews were conducted with professionals using purposive sampling technique. It is purposive, because only building professionals handling projects that are worth over eight million USD are consulted/ interviewed. The professionals included 15 project managers, nine quantity surveyors, five site engineers and one senior technical officer of a waste management department/ unit. The interviews were on issues relating to material waste and cost overruns at the post- contract stage of a project. The collected data were analysed manually, using the deductive approach. This involves constant comparative analysis of the data to generate common patterns on material waste and cost overrun. The research found that poor quality-of- procurement management, construction management, and site management would cause material waste, which contributes to project cost overruns. A good-quality procurement management entails procuring the appropriate materials, at the right time and in accordance with specifications. Rework, site accidents, inadequate site security/ fencing, poor site organisation and discipline, Ibrahim Saidu Dr Ibrahim Saidu, Department of Quantity Surveying, Federal University of Technology, P.M.B. 65, Minna, Niger State, Nigeria. +23 48037796321, email: Winston Shakantu Prof. Winston (M.W.) Shakantu Department of Construction Management, Faculty of Engineering, the Built Environment, and Information Technology, Nelson Mandela Metropolitan University, Port Elizabeth, South Africa. Phone: +27 785147492, email: DOI: http://dx.doi. org/10.18820/24150487/ as24i2.3 ISSN: 1023-0564 e-ISSN: 2415-0487 Acta Structilia 2017 24(2): 77-105 © UV/UFS mailto:saidu.ibr@futminna.edu.ng mailto:saidu.ibr@futminna.edu.ng mailto:Winston.shakantu@nmmu.ac.za mailto:Winston.shakantu@nmmu.ac.za http://dx.doi.org/10.18820/24150487/as24i2.3 http://dx.doi.org/10.18820/24150487/as24i2.3 http://dx.doi.org/10.18820/24150487/as24i2.3 Acta Structilia 2017: 24(2) 78 construction-site disputes, lack of experience, and lack of co-ordination among the parties all contribute to material waste and cost overruns. It can be concluded that proper attention to material waste issues has the potential to minimise the rate of cost overrun at the post-contract stage of a project. It is recommended that careful attention should be paid to the issues identified in this study, as they would help reduce the rate of material waste and cost overrun for projects. Keywords: Cost overrun, construction industry, material waste, post-contract stage Abstrak Materiaalafval en koste-oorskryding word geïdentifiseer as algemene probleme in die konstruksiebedryf. Hierdie probleme vind plaas in beide voor- en na-kontrakstadiums van ’n konstruksieprojek. As gevolg van ’n gebrek aan empiriese navorsing en lae vlak van bewustheid, gee die meeste bestuurders van konstruksieprojekte in Nigerië min aandag aan materiaalafvalkwessies wat koste- oorskryding beïnvloed. Hierdie artikel ondersoek die materiaalafvalkwessies wat koste-oorskryding in die na-kontrakstadium van bouprojekte beïnvloed. Die studie dek boukonstruksieprojekte in Abuja, Nigerië. In-diepte onder- houde met professionele persone is gehou met behulp van doelgerigte steekproefnemingstegnieke. Dit is doelgerig omdat slegs professionele persone wat projekte hanteer wat meer as agt miljoen dollar werd is, geraadpleeg/ ondervra is. Die professionele persone het 15 projekbestuurders, nege bourekenaars, vyf terreiningenieurs en een senior tegniese beampte van ’n afvalbestuursafdeling/-eenheid ingesluit. Die onderhoude het gegaan oor die kwessies wat verband hou met wesenlike afval en koste-oorskryding by die na-kontrakstadium van ’n projek. Die versamelde data is geanaliseer deur die deduktiewe benadering te gebruik. Dit behels konstante vergelykende analise van die data om algemene patrone op materiaalafval en koste-oorskryding te genereer. Die navorsing het bevind dat swak gehalte-van-verkrygingsbestuur, konstruksie- bestuur en terreinbestuur materiaalafval tot gevolg sal hê, wat bydra tot die koste van die projekkoste. Goeie gehalte-verkrygingsbestuur behels die verkryging van toepaslike materiale, op die regte tyd en in ooreenstemming met spesifikasies. Herstelwerk, terreinongelukke, onvoldoende terreinbeveiliging/- heining, swak terreinorganisasie en dissipline, geskilpunte op die bouplek, gebrek aan ondervinding en gebrek aan koördinasie tussen partye dra alles by tot materiaalafval en koste-oorskryding. Daar kan tot die gevolgtrekking gekom word dat behoorlike aandag aan materiaalafvalkwessies die potensiaal het om die koers van koste-oorskryding in die na-kontrakstadium van ’n projek te verminder. Daar word aanbeveel dat deeglik aandag gegee word aan die probleme wat in hierdie studie geïdentifiseer word, aangesien hulle sal help om die hoeveelheid afval en die koste-oorskryding vir projekte te verminder. Sleutelwoorde: Oorskryding van kostes, konstruksiebedryf, materiaalafval, na-kontrakstadium Saidu & Shakantu • A post-contract project analysis of material waste... 79 1. Introduction The construction industry, which plays a leading role in improving the quality of the built environment, is faced with the problems of waste, time overrun and cost overrun (Osmani, Glass & Price, 2008: 1147; Saidu & Shakantu, 2016a: 124). Material waste has become a serious problem and requires urgent attention in the construction industry (Adewuyi & Otali, 2013: 746). The majority of this waste has not been well managed, thus causing health and environmental problems (Imam, Mohammed, Wilson & Cheeseman, 2008: 469) and affecting the performance of many projects (Ameh & Itodo, 2013: 746; Saidu & Shakantu, 2016b: 555). Several authors reporting on the situation have disclosed the problem of material waste. For instance, 10%-15% of materials delivered to construction sites in the United Kingdom (UK) end up as waste (Osmani, 2011: 209; Saidu, 2016: 12). The United States (US) generates 164m tonnes of construction waste annually, representing 30%-40% of the country’s municipal solid waste (Osmani, 2011: 209). In Malaysia, 28.34% of the total waste sent to landfills originates from construction activities (Begum, Siwar, Pereira & Jaafar, 2007: 190). For every 100 houses built in Nigeria, there is adequate waste material to build another 10 houses (Ameh & Itodo, 2013: 748). Cost overrun is a global problem which makes it difficult for many construction projects to be completed within budget (Ameh & Itodo, 2013: 748; Memon, Abdul-Rahman, Zainun & Abd-Karim, 2013). Of construction project owners in the UK, 33.3% are faced with the problems of cost overrun (Abdul-Rahman, Memon & Abd. Karim 2013: 268). Flyvbjerg, Holm & Buhl (2004: 6) conducted a global study on cost overruns and concluded that cost overruns were found across 20 nations and five continents of the world, thus affecting 90% of completed projects in the world (Saidu & Shakantu, 2015: 95). The argument on how to totally remove cost overruns from projects has been on-going among the built environment professionals for the past seventy years (Apolot, Alinaitwe & Tindiwensi, 2013: 33). Relating material waste to cost overrun, Ameh & Itodo (2013: 748) believe that building material wastage on construction sites accounts for cost overruns. For instance, material waste accounts for an additional 15% of project-cost overruns in the UK; 11% in Hong Kong, and between 20% and 30% in The Netherlands. The majority of these findings were survey based. However, Saidu & Shakantu (2016c: 99) investigated the contributions of material waste to cost overruns in Abuja, Nigeria, using field measurement of onsite material waste and determination of amount of cost overrun for each project. Acta Structilia 2017: 24(2) 80 The research concluded that building material waste contributes to approximately 4% of cost overrun. The problems of material waste and cost overrun are occasioned by several causes at the pre- and post-contract stages of projects. The identification of these causes at these stages and the application of relevant control measures to minimise their occurrence is a step towards alleviating the consequences (Mou, 2008: 20; Oladiran, 2009: 2; Nagapan, Abdul-Rahman, Asmi & Hameed, 2012: 23; Saidu & Shakantu, 2015: 96). This research addresses the problem of hardly any attention being paid by the majority of managers of construction projects to the effects of material waste on cost overruns. Many studies have been conducted in this field. For instance, Tam, Shen & Tam (2007: 1471) assessed the levels of material wastage affected by sub-contracting relationships and projects types with their correlations on construction site; Ameh & Itodo (2013: 748) assessed professionals’ views of material wastage on construction sites and cost overruns. The study adopted a survey (questionnaire) research approach. Saidu & Shakantu (2015: 96) examined the relationship between quality of estimating, construction material waste generation and cost overruns in Abuja, Nigeria; Saidu & Shakantu (2016a: 124) examined the relationship between material waste and cost overrun in the construction industry using a thorough literature search and recommended further empirical investigations. Saidu & Shakantu (2016b: 555) developed a framework and an equation for managing construction-material waste and cost overruns but these are not empirically inclined. There is need for a research that provides an unprejudiced assessment of the material waste issues that have effects on cost overruns at the post- contract stage of a building project. Hence, this research examines the material waste issues that have effects on cost overruns at the post-contract stage of building projects by determining the material waste issues that relate to cost overruns at: a) the procurement stage of a project; (b) the site management stage of a project, and (c) the construction management stage of a project. 2. Literature review It is important to note that Figure 1 is not all about construction waste, but that it attempts to show the root cause of ‘material waste’ and ‘cost overrun’ from construction waste. Moreover, Tables 1, 2 and 3 contain information about material waste that relates to cost overrun and not only construction waste. Therefore, information about material waste dominated the entire literature review. Saidu & Shakantu • A post-contract project analysis of material waste... 81 2.1 Material waste and cost overrun Construction waste is a global challenge facing construction practitioners. It can have a significant impact on time, cost, quality and sustainability, as well as the success of projects (Nagapan et al., 2012: 22). It is the difference between purchase and actual use (Al-Hajj & Hamani, 2011: 2). Construction waste has been described as any constituent generated, as a result of construction work, and abandoned, whether or not it has been processed or stocked up before being abandoned (Yuan, Lu & Hao, 2013: 484; Hussain, Abdul Rahman & Memon, 2013: 32). Cost is considered one of the most significant issues and a driving force of project success. It has been regarded as a major concern throughout the project management life cycle. In spite of its recognised significance, it is common for a construction project to fail to achieve its goals within the budget. Cost overrun, according to Azhar, Farooqui & Ahmed (2008: 499), is simply an occurrence, where the final or actual cost of a project surpasses the original or initial estimates. Therefore, cost overrun is a very common issue that affects most of the projects in the construction industry (Azhar et al., 2008: 499), while waste can have a significant effect on the success of a construction project, since it specifically has a major impact on the construction costs (Nagapan, Abdul-Rahman, Asmi & Hameed 2012: 22). In Nigeria, the lowest average reported percentage of cost overrun on a project was 14% (Hussain et al., 2013: 32; Ameh, Soyingbe & Odusanmi, 2010: 49). This problem, according to Ogunsemi & Jagboro (2006: 257), is attributed to a wrong cost-estimation method adopted at the early stage of building projects. Ameh & Itodo (2013: 749) assert that material wastage on site leads to an increase in the final cost of the building project. As materials are wasted, more are procured, thus affecting the estimated cost (Teo, Abdelnaser & Abdul, 2009: 257). Ameh and Itodo (2013:754) highlighted that wastages from the following materials contribute to the total project cost: concrete 4%; blockwork 10%; waste from screeding and plastering 15%; packaging 5%, and formwork is based on the number of times it is re-used. Furthermore, research evidence has shown (see Tables 1, 2 and 3) that the main factors causing construction material waste are similar to those causing construction- cost overruns on site; hence, Nagapan, Abdul-Rahman & Asmi (2012: 2-3) (see Figure 1) categorised cost overruns and time overruns as part of non-physical waste, and other material waste as physical waste on a construction site. This shows that cost overruns, time overruns Acta Structilia 2017: 24(2) 82 and construction material waste are generally categorised as waste. This is supported by Ma (2011: 118) who defines waste as anything that does not add value. Therefore, cost overruns, material waste and material waste that may be lost to landfills do not add value to projects. Therefore, Nagapan, Abdul-Rahman & Asmi (2012: 2-3) assert that construction waste is not all about the quantities of materials that are wasted, but that it is also focused on factors such as overproduction, waiting time, material handling, inventories, and the unnecessary movement of workers that constitute a significant part of non-physical waste, to which the construction industry always pays the least attention. It is clear from Figure 1 that, since construction waste entails both the physical and the non-physical waste, there is, therefore, a relationship between cost overrun emanating from the non-physical waste and material waste from the physical waste, as they both originate from the same waste family (Saidu & Shakantu, 2015: 97). Figure 1: Classification of construction waste   Figure 1: Classification of construction waste Adapted from: Nagapan, Abdul-Rahman & Asmi, 2012: 2 Furthermore, the causes of material waste and those of cost overruns identified from the literature are similar. These causes occur as a result of one, or a combination of several causes at different stages of a project (the pre- and the post-contract stages), and they are crucial in identifying effective cost performance and sustainable construction (Saidu, 2016: 61). 2.2 Material waste and cost overrun at the post-contract stage of projects The causes of material waste and cost overruns at the post-contract stage of projects are identified in three major phases, namely the quality-of-procurement management, the quality-of-construction management, and the quality-of-site management. Tables 1, 2 and 3 present the results of different studies on the causes of material Saidu & Shakantu • A post-contract project analysis of material waste... 83 waste and those of cost overruns at these three phases of the post- contract stage. In all three tables, columns 2-3 are combined under the heading “material waste”, while columns 4-5 are combined under the heading “cost overrun”. These columns depict that each material waste cause listed in column 1 was identified and linked under a source and the location/country in columns 2-3 as well as in columns 4-5. 2.2.1 Procurement management phase Table 1 lists the causes of material waste related to the causes of cost overruns with respect to the procurement management phase of a building construction project. Table 1: The material waste causes that are similar to those of cost overruns with respect to quality-of-procurement management Causes of material waste related to the causes of cost overruns with respect to the procurement management phase of a project Material waste Cost overruns Author and date Location Author and date Location Procurement and transportation Errors/mistakes in material ordering/ procurement Nagapan, Abdul- Rahman, Asmi & Hameed (2012: 23) Malaysia Allahaim & Liu (2012: 5-6) Saudi Arabia Procuring items not in compliance with specification Adewuyi & Otali (2013: 748); Osmani et al. (2008: 23) Rivers, Nigeria; UK Allahaim & Liu (2012: 5-6) Saudi Arabia Errors in shipping/ supply Osmani et al. (2008: 1149); Nagapan et al. (2012: 23) UK; Malasia Nega (2008: 48) Ethiopia Acta Structilia 2017: 24(2) 84 Causes of material waste related to the causes of cost overruns with respect to the procurement management phase of a project Material waste Cost overruns Author and date Location Author and date Location Mistakes in quantity surveys: Poor estimate for procurement (over- procuring) Nagapan et al. (2012: 23) Malaysia Aziz (2013: 57); Allahaim & Liu (2012: 5-6) Egypt; Saudi Arabia Wrong material delivery procedures Nagapan et al. (2012: 23) Malaysia Aziz (2013: 57) Egypt Delivery of substandard materials Nagapan et al. (2012: 23) Malaysia Nega (2008: 48) Ethiopia Damage of material during transportation Osmani et al. (2008: 1149) UK Nega (2008: 48) Ethiopia Late delivery/ Inadequate delivery schedule Nguyen, Gupta & Faniran (nd: 6) Geelong, Australia Al-Najjar (2008: 51); Abdul Rahman, Memon & Abd. Karim (2013: 1965) Gaza Strip; Malaysia Poor material handling Osmani et al. (2008: 1149); Nagapan et al. (2012: 23) UK; Malaysia Ameh, Soyingbe & Odusanmi (2010: 61-62) Nigeria Poor protection of materials and damage during transportation Osmani et al. (2008: 1149); Aiyetan & Smallwood (2013: 1168) UK; Lagos, Nigeria Nega (2008) Ethiopia Over- allowance (difficulties in ordering less) Osmani et al. (2008: 1149); Nagapan et al. (2012: 23) UK; Malaysia Allahaim & Liu (2012: 5-6) Saudi Arabia Saidu & Shakantu • A post-contract project analysis of material waste... 85 Causes of material waste related to the causes of cost overruns with respect to the procurement management phase of a project Material waste Cost overruns Author and date Location Author and date Location Frequent variation orders Nguyen et al. (nd: 6) Geelong, Australia Aziz (2013: 57); Baloyi & Bekker (2011: 55) Egypt; South Africa Poor product knowledge Nagapan et al. (2012: 23) Malaysia Jackson (2002: 4) Reading Difficulties of vehicles in accessing site Osmani et al. (2008: 1149); Nagapan et al. (2012: 23) UK; Batu, Malaysia Allahaim & Liu (2012: 5-6); Zewdu & Aregaw (2015: 185) Saudi Arabia; Ethiopia Manufacturers Poor quality of materials Adewuyi & Otali (2013: 748) Nigeria Ameh et al. (2010: 61-62) Nigeria Non-standard sizes of materials Osmani (2011) UK Le-Hoai, Lee & Lee (2008: 370) Vietnam Poor product information Nagapan et al. (2012: 23) Malaysia Allahaim & Liu (2012: 5-6) Saudi Arabia Lack of awareness Al-Hajj & Hamani (2011: 221) UAE Ameh et al. (2010: 61-62) Nigeria Suppliers Poor supply chain management Al-Hajj & Hamani (2011: 221) UAE Ameh et al. (2010: 61-62) Nigeria Supplier errors Odusami, Oladiran & Ibrahim (2012: 63) Nigeria Nega (2008: 48) Ethiopia Poor product incentive Nagapan et al. (2012: 23) Malaysia Allahaim & Liu (2012: 5-6) Saudi Arabia Acta Structilia 2017: 24(2) 86 Causes of material waste related to the causes of cost overruns with respect to the procurement management phase of a project Material waste Cost overruns Author and date Location Author and date Location Poor handling of supplied materials Osmani et al. (2008: 1149); Ameh & Itodo (2013: 753) UK; Nigeria Ameh & Itodo (2013: 753) Nigeria Poor methods of unloading materials supplied in loose form Adewuyi & Otali (2013: 748) Nigeria Nega (2008: 48) Ethiopia 2.2.2 Construction management phase Table 2 lists the causes of material waste related to the causes of cost overruns with respect to the construction management phase of a building project. Table 2: The relationship between the causes of material waste and cost overruns with respect to the quality of construction management Causes of material waste related to the causes of cost overruns with respect to the construction management phase of a project Material waste Cost overruns Author and date Location Author and date Location Contractors Incorrect scheduling and planning Osmani et al. (2008: 1149) UK Abdul Rahman et al. (2013: 1965) Malaysia; Inappropriate contractor’s policies Nagapan et al. (2012: 23) Malaysia Aziz (2013: 57) Egypt Lack of awareness Al-Hajj & Hamani (2011: 221-228) UAE Aziz (2013: 57) Egypt Saidu & Shakantu • A post-contract project analysis of material waste... 87 Causes of material waste related to the causes of cost overruns with respect to the construction management phase of a project Material waste Cost overruns Author and date Location Author and date Location Lack of experience Nagapan et al. (2012: 23) Malaysia Abdul Rahman et al. (2013: 1965); Ameh et al. (2010: 62) Malaysia; Nigeria Poor site management and supervision Nagapan et al. (2012: 23); Ameh & Itodo (2013: 753) Malaysia; Nigeria Le-Hoai et al. (2008: 370); Allahaim & Liu (2012: 6) Vietnam; Saudi Arabia Poor building techniques Nagapan et al. (2012: 23) Malaysia Aziz (2013: 57) Egypt Incompetent subcontractor/ supplier Nagapan et al. (2012: 23) Malaysia Ameh et al. (2010: 61-62) Nigeria Poor financial controls on site Al-Hajj & Hamani (2011: 221) UAE Shanmugapriya & Subramanian (2013: 737-738) India Use of unskilled labour to replace skilled ones Nagapan et al. (2012: 23) Malaysia Memon et al. (2013: 10) Malaysia Culture Lack of incentive Al-Hajj & Hamani (2011: 221) UAE Memon et al. (2013: 10) Malaysia Lack of training and development Al-Hajj & Hamani (2011: 221); Adewuyi & Otali (2013: 748) UAE; Nigeria Olawole & Sun (2010: 522) UK Lack of support from senior management Al-Hajj & Hamani (2011: 221) UAE Aziz (2013: 57); Allahaim & Liu (2012: 5-6) Egypt; Saudi Arabia Lack of awareness among practitioners on waste management Al-Hajj & Hamani (2011: 222) UAE Ameh et al. (2010: 62) Nigeria Acta Structilia 2017: 24(2) 88 Causes of material waste related to the causes of cost overruns with respect to the construction management phase of a project Material waste Cost overruns Author and date Location Author and date Location Workers Workers’ mistakes or errors during construction Al-Hajj & Hamani (2011: 226) UAE Shanmugapriya & Subramanian (2013: 737-738) India Incompetent workers Nagapan et al. (2012: 23) Malaysia Aziz (2013: 57); Olawole & Sun (2008: 522) Egypt; UK Poor workers’ attitude Nagapan et al. (2012: 23) Malaysia Aziz (2013: 57) Egypt Lack of experienced workers Nagapan et al. (2012: 23) Malaysia Shanmugapriya & Subramanian (2013: 737); Love, Edward & Irani (2011) India; UK Shortage of skilled workers Nagapan et al. (2012: 23) Malaysia Abdul Rahman et al. (2013: 1965); Olawole & Sun (2010: 522) Malaysia; India; UK Inappropriate use of materials and equipment Wahab & Lawal (2011: 252) Nigeria Allahaim & Liu (2012: 5-6) Saudi Arabia Poor workmanship Odusami et al. (2012: 63) Aiyetan & Smallwood (2013: 1168) Nigeria; Lagos, Nigeria Nega (2008: 48) Ethiopia Damage caused by workers Nagapan et al. (2012: 23); Al-Hajj & Hamani (2011: 221) Malaysia; UAE Allahaim & Liu (2012: 5-6) Saudi Arabia 2.2.3 Site management phase Table 3 lists the causes of material waste related to the causes of cost overruns with respect to the site management phase of a building construction project. Saidu & Shakantu • A post-contract project analysis of material waste... 89 Table 3: The relationship between the causes of material waste and cost overruns with respect to quality of site management Causes of material waste related to causes of cost overruns with respect to site management phase of a project Material waste Cost overruns Author and date Location Author and date Location Wrong material/ equipment storage/stacking Nagapan et al. (2013: 23) Malaysia Ubani, Okorocha & Emeribe (2011: 76) Nigeria Transfer of materials from storage to application Osmani et al. (2008: 1149) UK Ubani et al. (2011: 76) Nigeria Damage of materials by other trades Aiyetan & Smallwood (2013: 1168) Lagos, Nigeria Jackson (2002: 4) Reading Poor site storage area Osmani et al. (2008: 1149); Odusami et al. (2012: 63) UK; Nigeria Jackson (2002: 4) Reading Long distance from storage to application point Osmani et al. (2008: 1149) UK Damage by weather Osmani et al. (2008: 1149); Wahab & Lawal (2011: 252) UK; Nigeria Allahaim & Liu (2012: 6); Memon et al. (2013: 10) Saudi Arabia; Malaysia Security Inadequate site security/Fencing Nguyen et al. (nd) Geelong, Australia Allahaim & Liu (2012: 5-6) Saudi Arabia Theft Osmani et al. (2013: 1149) UK; Nigeria Allahaim & Liu (2012: 5-6) Saudi Arabia Vandalism, sabotage pilferage, and material damage Osman et al. (2008: 1149); Ameh & Itodo (2013: 753) UK; Nigeria Allahaim & Liu (2012: 5-6) Saudi Arabia Power and lighting problems on site Nguye et al. (nd: 6) Geelong, Australia Allahaim & Liu (2012: 5-6) Saudi Arabia Acta Structilia 2017: 24(2) 90 Causes of material waste related to causes of cost overruns with respect to site management phase of a project Material waste Cost overruns Author and date Location Author and date Location Site conditions Poor site management Odusami et al. (2012: 63) Nigeria Abdul Rahman et al. (2013: 288) Malaysia Poor site and unforeseen ground conditions Wahab & Lawal (2011: 252); Aietan & Smallwood (2013: 1168) Nigeria; Lagos, Nigeria Aziz (2013: 57); Allahaim & Liu (2012: 5-6) Egypt; Saudi Arabia Leftover materials on site Osmani (2011: 38) UK Ubani et al. (2011: 76) Nigeria Waste resulting from packaging Osmani (2011: 38) UK Allahaim & Liu (2012: 5-6) Saudi Arabia Lack of environmental awareness Nagapan et al. (2012: 23) Malaysia Ubani et al. (2011: 76) Nigeria Difficulties in accessing construction site Nagapan et al. (2012: 23) Malaysia Allahaim & Liu (2012: 5-6) Saudi Arabia Site congestion and Interference of other crews Osmani (2011: 38) UK Le-Hoai et al. (2008: 370) Vietnam Inadequate site investigation Osmani et al. (2008: 1149) UK Shanmugapriya & Subramanian (2013: 737-738) India Disputes on site Adewuyi & Otali (2013: 748) Nigeria Allahaim & Liu (2012: 5-6) Saudi Arabia Extra materials ordered are discarded instead of carrying over to next site Oladiran (2009: 2) Nigeria Allahaim & Liu (2012: 5-6) Saudi Arabia Equipment failure on site Adewumi & Otali (2013: 748) Nigeria Shanmugapriya & Subramanian (2013: 737-738) India Saidu & Shakantu • A post-contract project analysis of material waste... 91 Causes of material waste related to causes of cost overruns with respect to site management phase of a project Material waste Cost overruns Author and date Location Author and date Location Rework Al-Hajj & Hamani (2011: 225); Adewuyi & Otali (2013: 748); Oladiran (2009: 2); Ameh & Itodo (2013: 753) UAE; Rivers, Nigeria; Nigeria; Nigeria Shanmugapriya & Subramanian (2013: 737-738); Le-Hoai et al. (2008: 370) India; Vietnam Site accidents Odusami et al. (2012: 63) Nigeria Allahaim & Liu (2012: 5-6); Le-Hoai et al. (2008: 370) Saudi Arabia; Vietnam Lack of communication Wahab & Lawal (2011: 252) Nigeria Abdul Rahman et al. (2013: 1965) Malaysia 3. Research methodology Although the research analysis was done using a deductive approach, the research method applied for this research was inductive reasoning. This is a reasoning strategy that intends to learn about the phenomena under investigation by applying a less structured methodology in order to obtain richer and more detailed information (Sutrisna, 2009: 9). To achieve this, a qualitative research method that is rooted in the phenomenological research paradigm was applied. This helped the researchers study the attitudes and behaviours of the research subjects within their natural settings (Babbie & Mouton, 2010: 51). This qualitative method involves analysing words; it refers to issues relating to people, objects and situations, and it focuses on naturally occurring, ordinary events in their natural settings (Farrell, 2011: 6). This enables the researchers to examine the material waste issues that affect cost overruns at the post-contract stage of a construction project. Based on the research problem advanced in this study, for instance, the majority of managers of construction projects pay hardly any attention to the effects of material waste on project cost overrun. This has prompted Acta Structilia 2017: 24(2) 92 the researchers to apply the qualitative method, in order to identify and examine these issues. The study population consists of building construction projects in Abuja, the Federal Capital Territory of Nigeria. Abuja was selected because it is one of the metropolitan cities of Nigeria with the highest population of professionals in the built environment and with many ongoing construction projects. 3.1 Sampling method The sampling method was purposive/judgmental, because only building-construction professionals handling projects that are worth 1.6 billion Naira/eight million USD and above were consulted/ interviewed. Unlike projects of lesser value, those worth eight million USD and above are categorised as big projects that are likely to be handled by more experienced professionals, who might be more familiar with the issues leading to material waste and cost overruns (Saidu & Shakantu, 2016c: 104). Through purposive sampling, the research targeted the most visible and experienced leaders. 3.2 Sample size Leedy & Ormrod (2014: 220) believe that the size of a purposive sampling technique for a phenomenological research ranges between five and 25 participants. For this research, semi-structured, in-depth interviews were conducted with 30 construction professionals, comprising 15 project managers, nine quantity surveyors, five site engineers and one senior technical officer of a waste-management department on the issues that relate to material waste and cost overruns at the post-contract stage of a construction project. 3.3 Data collection The research instrument (interview guide) enabled the researchers to be consistent with the questions posed to the respondents. It also enabled the collection of data based on the perception of the construction professionals in Abuja with regard to the issues that link material waste to cost overruns in the construction industry. Twelve questions based on the objectives of this research were generated. The interview guide was structured in three major groups, namely quality of procurement management, quality of construction management and quality of site management (see Appendix). Probing questions were asked during discussion with the interviewees, in order to obtain further information. An average of 35 minutes was spent in conducting each interview. The interviews Saidu & Shakantu • A post-contract project analysis of material waste... 93 were conducted between December 2014 and March 2015. The approximate conversion rates as at November 2014 were Nigerian Naira to US dollar = ₦200 = 1USD. All 30 respondents identified in this research through the purposive sampling method responded to all the questions presented for discussion. 3.4 Data analysis The recorded, transcribed and interpreted interview data were analysed, using the ‘deductive approach’. The application of the ‘deductive analysis’ of data in qualitative research enabled the researchers to extensively condense raw data into a brief and summary format, and to establish clear links between the research purpose and the summary findings derived from the raw data (Dey, 2005: 55). The data in this analysis was done manually after each respondent’s views were coded and similar views were brought together under a theme/heading. This method involves constant comparative analysis of the data after it has been sorted and coded to generate knowledge about any common pattern in the interviewees’ evidence on material waste and cost overrun. The analysis began by comparing the opinions of the first two interviewees. The process continued with a comparison of the data from the comments and inputs from each new interviewee, until all the responses had been compared with each other. The similarities and differences between the interviewees’ responses were used to develop a conceptualisation of the possible association between the various data items. The results are presented under subthemes under the following headings: quality of procurement management, quality of construction management, and quality of site management. 4. Results and discussion The results are the summary of the interviews conducted with the 30 respondents after linking the similarities together. These are the key issues realised from the interviews. They are not literatures, but qualitative results. For presentation and discussion purposes, a summary of the interview results is presented under the following headings/themes, which are in line with the set objectives of the research, namely quality of procurement management; quality of construction management, and quality of site management. Acta Structilia 2017: 24(2) 94 4.1 Quality of procurement management 4.1.1 The quality of procurement management in the respondents’ organisations The majority of organisations/firms procure materials strictly in accordance with project specifications; with an efficient and well- organised procurement management; they have the know-how of what to procure, what quantity to procure, at what cost to procure, and where to procure. Some companies have the knowledge of current material prices, both locally and internationally, while few lack such knowledge. Some have a network of procurement departments, both locally and internationally, in case the projects require foreign materials. 4.1.2 Contribution of materials procurement to waste-generation and cost overruns Procuring the appropriate materials, at the right time, in accordance with the specifications, and proper material handling and good product knowledge would reduce material waste and cost overruns. This result corroborates the findings of Osmani et al. (2008: 1147) and Nagapan et al. (2012: 22) who highlighted poor material handling as a cause of material waste, and Ameh et al. (2010: 49) who also noted the same issue as a cause of cost overrun. 4.1.3 Contributions of quality of firms’ procurement management to material-waste generation and cost overruns A good quality-procurement management team should envisage better transportation of materials, order the appropriate quantity of materials, and provide easy access roads. Where these cannot be envisaged, waste would inevitably occur and contribute to cost overruns. In the absence of a competent and experienced procurement management, a job would probably be given to an incompetent contractor, who might end up wasting materials, thus leading to cost overruns. Moreover, lack of quality control in procurement and adequate estimation for procurement, as stated in project specifications, may result in wastage of materials and contribute to cost overrun. This finding also supports the literature identified in section 2 of this study. Saidu & Shakantu • A post-contract project analysis of material waste... 95 4.1.4 Material waste causes on project cost-overrun with respect to quality of procurement management The following material-waste causes resulted in cost overruns at this stage: procuring items not in compliance with the specifications; engaging inexperienced personnel in estimation and procurement; procuring wrong quantity of materials; errors in shipping; damage of material during transportation, and lack of awareness. These results are in line with the causes of material waste that are similar to the causes of cost overrun identified in section 2 of this research study. 4.2 Quality of construction management 4.2.1 Quality of construction management based on the respondent’s experience Quality of construction management entails managing the entire construction process from inception to completion with all the necessary management tools. Some respondents believe that it is the practical way of achieving design reality through co-ordinating, controlling, organising, communicating, scheduling, motivating, proper building techniques, and good workmanship. Some respondents view construction management as the pillar of every construction work, which has to do with the management of people, plant, materials, equipment, money, time, and the entire construction process. 4.2.2 Relationship between the interviewee firms’ construction management, material-waste generation and cost overruns The respondents were not fully satisfied with their organisations’ approach to construction management. Some disclosed that their firms/organisations were operating far below the average level in terms of construction management; some at the average level, while some still have a very long way to go. The reason for this is that there are situations where projects are not delivered on time, and sometimes within the budgeted cost. However, very few were doing above average. These are experienced and always plan ahead; hence, they generate less waste and cost overruns. 4.2.3 Contribution of subcontractors and suppliers to material-waste generation and cost overruns Both the subcontractors and the suppliers contribute to material- waste generation and cost overruns. Subcontractors are profit- oriented individuals and the waste they generate directly affects Acta Structilia 2017: 24(2) 96 their profits. Most of the contract agreements require subcontractors to generate waste at their own risk, which makes them more careful about the amount of waste they generate. For the suppliers, the quality control department evaluates the supplied product to ensure that they conform with the project’s specification. 4.2.4 Impact of rework and mistake/error on material-waste and cost overruns Inexperienced professionals/personnel or working contrary to project specification/contract lead to rework and mistakes/errors. An abortive work is already a waste, and it would require the same type of materials, the same labour, and the same costs to re-build. This result corroborates the findings of Aziz (2013: 52) who concluded that abortive works contribute to cost overruns. 4.2.5 Material-waste causes that affect cost overruns with respect to quality-of-construction management The following material-waste causes affect project-cost overrun with respect to quality-of-construction management: engaging incompetent workers; rework; incorrect scheduling and planning; shortage of skilled workers; lack of experience; poor financial controls on site; poor staff workers’ relationship; lack of awareness of waste management; lack of incentive, and the use of unskilled labour to replace skilled ones. These results corroborate the findings outlined in section 2 of this research. 4.3 Quality of site management 4.3.1 Respondents’ understanding of site management and its contributions to material waste and cost overrun Site management is an aspect of construction management that deals with the planning, controlling, co-ordinating, communicating, motivating, scheduling, and organising of the entire activities on the site, including the 5Ms (men, machines, money, materials, and management) to achieve the desired project objectives; it involves site security, access road, minimisation of wasteful time, timely provision of materials, and site safety; it has to do with the management of the routine activities on site, and it includes a certain group of people that administer the day-to-day running of a site from inception to completion of a project. Therefore, site management contributes to material waste and cost overruns when Saidu & Shakantu • A post-contract project analysis of material waste... 97 the management of the site issues is poor or not properly managed or addressed. 4.3.2 Contributions of site security, site accident, and site disputes to material-waste generation and cost overruns Inadequate site security would lead to pilfering/thefts and damage/ sabotage of materials on site. When the site is not properly organised and disciplined, accidents are bound to occur, and these might affect the workers, the structure, or even both. 4.3.3 Material waste causes that affect cost overruns with respect to quality-of-site management The following material-waste causes affect cost overruns with respect to quality of site management stage: inadequate site security/ fencing; poor site organisation and discipline; construction-site disputes; poor site management and the 5Ms; lack of experience; poor construction planning and control; lack of co-ordination among the parties; poor site storage area; communication problems and poor site supervision; problems relating to on-site health and safety; wrong location of cranes on site; inappropriate records of materials, and lack of environmental awareness. These results support the findings highlighted in section 2 of this study. 5. Conclusion and recommendations Material waste and cost overrun are common problems in the construction industry at both the pre- and post-contract stages of a construction project. As a result of a dearth of empirical research and a low level of awareness, the majority of managers of construction projects in Nigeria pay hardly any attention to material waste issues that affect cost overrun. This article examined the material waste issues that affect cost overruns at the post-contract stage of building projects. The research concludes that both the literature and the empirical findings from the study have established a link between the issues on material waste and cost overruns at the post-contract stage of a project (procurement, construction management, and site management stages). 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Can you tell me about the quality of procurement manage- ment in your organisation/industry? 2. Does the quality of materials procurement contribute to material waste-generation? What about cost overruns? 3. Does the quality of your firm’s procurement management contribute to material-waste generation and cost overruns? 4. Based on your experience, what are the material waste causes that affect cost-overrun with respect to quality of procurement management? Saidu & Shakantu • A post-contract project analysis of material waste... 105 b) Quality of construction management 1. Based on your experience, what is the quality of construction management? 2. How can you relate the quality of your firm/organisation’s construction management to material waste generation and cost overrun 3. Do sub-contractors and suppliers in any way affect the material waste generation and cost overrun? 4. Does rework have any impact on the material waste generation and cost overrun? What about mistakes/errors? 5. What are the material waste causes that affect cost overruns with respect to the quality of construction management? c) Quality of site management 1. What is your understanding of ‘site management’? How does site management contribute to material waste and cost overrun? 2. How do the site security, site accident and site dispute affect material waste generation and cost overrun? 3. What are the material waste causes that affect cost overruns with respect to the quality of site management?