Study On Rework Factors And Rework Cost Of Residential Projects

Rework is a common phenomenon in the process of China’s residentialengineering construction, yet effective management measures conducted has beenlimited by participants, so frequently leads to low project quality, longer constructionperiod and an increase in cost. Therefore, there is a great significance to strengthen themanagement and control rework. This paper presents a overview and summary of thesystem to the rework affecting residential projects. Research methods includingliterature research, expert interviews, questionnaire survey，case studies, field researchand mathematical methods of statistical analysis are adopted. Through theorycombined with practice, the final proposed measures will be put forward to reduceresidential projects rework.Before rework could be reduced and prevented, however the root causes must firstbe identified and classified. Thirty-nine variables which affect the rework of residentialprojects have been determined through literature studies and expert interviews. Threemain variables leading to rework are acquired by mean value sequencing method:Unclear and ambiguous project management process leads to design or constructionerrors; Poor quality of construction technology; Use of poor construction materials.Thirty-nine variables have been classified by use of the factor analysis and11commonfactors which can be clearly named are extracted. The11factors can be renamed as:design management related factor, project instructions management related factor,contractor field management related factor, project scope related factor, project processmanagement related factor, initiative rework related factor, project plan changes relatedfactor, subcontractor related factor, contract documentation related factor, ownerrelated factor and external environment related factor.Study on the rework cost theory is mainly based on project cost theory, qualitycost theory and failure cost theory. This paper put forward the definition of rework costas the unnecessary spending cost of re-doing a process or activity that was incorrectlyimplemented the first time. Rework cost consist of direct rework costs and indirectrework cost. There are four main factors affecting rework costs as human factors,material factors, machinery and equipment factors and other hidden factors.Research methods of case studies and field research are adopted for studying on residential projects rework costs in China. It is found that the rework cost is4.95%ofthe total investment of the project. It is also found that the contractor field managementrelated factor accounted for20.10%of the total rework cost; design management relatedfactor accounted for18.91%of the total rework cost; owner related factor accounted for14.73%of the total cost of rework. In addition, It is also found that the owners take upthe largest proportion of rework cost, close to50%. The three main sub-reason affectingrework cost are Poor communication/coordination between owner and end-users, designerror/omission due to design task too much, time boxing, inappropriate/Contradictoryproject instructions initiated by managers.Finally, this paper put forward corresponding organization measures, managementmeasures, technical measures and economic measures. These measures will help toimprove the rework management capabilities of managers and to minimize and controlrework occurs.