Aim: The aim of this study is to evaluate how faulty design affects construction and maintenance of building projects in Asaba, Delta state with a view to establishing their level of occurrence and providing ways of mitigating them. Study Design: It was a survey research, the study was effected via literature review and a well-structured questionnaire. Likewise, interviews were carried out to substantiate the findings of the questionnaire survey. Place and Duration of the Study: The study was conducted in Asaba, Delta State, Nigeria for a period of 2 years. Methodology: Being a survey research, 80 questionnaires were administered to the respondents and only 67 were returned which represents 84% response rate. The data collected was presented and analysed using tables, frequency, mean score and relative importance index. The analysis was aided by a computer-based software, named Statistical Package of Social Sciences (SPSS) version 22. Results: The study found out that; inadequate structural design, lack of details, lack of inspection, inaccurate measurement, not complying with specification, use of expired materials, wrong use of equipment, inadequate performance of equipment, unclear specification were rated as the most severe defects in each of the groups. Also, the findings showed that defects found in the study are categorized as design deficiencies, material deficiencies, construction deficiencies and subsurface deficiencies. Conclusion: The study concluded recommending that the designers must take into account maintenance issues during design and construction stages. Also, proper sensitization of building contractors with respect to durable materials which are suitable to the immediate environmental condition should be purse as well as the construction techniques and competence of workforce. Likewise, strict quality assurance and quality control (QA/QC) program should be encouraged during project design and construction.