Timely implementation of construction works (at the scheduled time) is vital for both the investor and the contractor. Yet construction projects, even those perfectly planned and organized, run the risk of delays. Despite many tools supporting construction management, delays keep occurring in construction projects. The present paper presents the findings of a survey aimed at identifying the most important causes of delays in construction works from the client's perspective. A factor analysis that was performed allow to interpret the dependencies between them. The knowledge can be helpful for minimizing the risk of delays. (C) 2015 Published by Elsevier Ltd.