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, 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

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尼日利亚阿布贾建筑工地的材料浪费和成本超支的合同后项目分析

材料浪费和成本超支已被确定为建筑行业的常见问题。这些问题在建设项目的合同前和合同后阶段均会发生。由于缺乏实证研究和认识水平低下，尼日利亚大多数建设项目的管理人员几乎不关注影响成本超支的物质浪费问题。本文研究了在建筑项目合同后阶段影响成本超支的材料浪费问题。这项研究涵盖了尼日利亚阿布贾的建筑项目。使用目的性抽样技术与专业人员进行了深入访谈。这是有目的的，因为仅咨询/采访处理价值超过800万美元的项目的建筑专业人员。专业人员包括废物管理部门/部门的15名项目经理，9名工程测量师，5名现场工程师和1名高级技术官员。访谈涉及的是项目合同后阶段与材料浪费和成本超支有关的问题。使用演绎方法手动分析收集的数据。这涉及对数据进行持续的比较分析，以生成关于材料浪费和成本超支的通用模式。研究发现，不良的采购质量管理，施工管理和工地管理会导致材料浪费，从而导致项目成本超支。高质量的采购管理需要在正确的时间并按照规格采购合适的材料。返工，工地事故，工地安全/围墙不足，不良的现场组织和纪律，施工现场纠纷，经验不足以及各方之间缺乏协调，都造成了材料浪费和成本超支。可以得出结论，对材料浪费问题的适当关注可能在项目的合同后阶段最大程度地降低成本超支率。建议应仔细注意本研究中确定的问题，因为它们将有助于减少项目的物料浪费率和成本超支。关键字：成本超支，建筑业，材料浪费，合同后阶段 可以得出结论，对材料浪费问题的适当关注可能在项目的合同后阶段最大程度地降低成本超支率。建议应仔细注意本研究中确定的问题，因为它们将有助于减少项目的物料浪费率和成本超支。关键字：成本超支，建筑业，材料浪费，合同后阶段 可以得出结论，对材料浪费问题的适当关注可能在项目的合同后阶段最大程度地降低成本超支率。建议应仔细注意本研究中确定的问题，因为它们将有助于减少项目的物料浪费率和成本超支。关键字：成本超支，建筑业，材料浪费，合同后阶段