Productivity represents efficient and effective utilisation of scarce resources to achieve set objectives. Based on Pareto principle, this study aims to identify the nature of and improvement measures for the 20% of the factors causing 80% of the on-site productivity problems in the New Zealand construction industry. Qualitative data collected using pilot interviews formed the basis for questionnaire surveys of project managers, contractors and subcontractors in New Zealand. The quantitative data was analysed using the multi-attribute method and Pareto analysis. Results showed that the factors influencing on-site productivity comprise (in order of influence): project management/project team characteristics, project finance/cash flow, workforce characteristics, project design/characteristics, unforeseen events, technology/process, statutory compliance and wider external forces. Overall, it was found that the way a project is managed, financed and managed, coupled with the workforce and project characteristics, account for the bulk of the on-site productivity problems encountered during its implementation. The levels of impact and occurrence frequencies of the variables under the broad factor categories are reported; these are recommended as guide to optimal utilization of the available resources in addressing the constraints with a view to achieving significant on-site productivity improvement
