This study investigates various causes of variation orders in construction projects with the objective of classifying causes into variation order groups using the discriminant analysis technique. Fifty-three causes of variation orders were identified and used to design a research questionnaire for collection of information from clients, consultants and contractors. Snowballing sampling technique was used to select Forty-two respondents and only thirty-three responses were used for data analysis. Results indicate that client financial problems, honest wrong belief of consultants, obstinate nature of consultant, defective workmanship of contractor and lack of specified construction manager by contractors were the causes of variation order that discriminate between moderate and high variation order causes. From the findings a discriminant model for classifying variation order was constructed. Practical implications of the findings indicate that private and corporate clients should ensure guaranteed financial sources for their projects before embarking on them while government clients should ensure that budgetary allocations are made available for the projects. The study concludes that five causes of variation orders are important for its classification. Evolving model is strongly recommended to stakeholders and practitioners for identifying and classifying variation orders in their recently completed projects. It serves as early warning system for minimising variation orders in future projects.
Key Words: Variation Order, Classification Model, Construction Projects, Nigeria