Cost and time overruns are major issues faced by the construction industry worldwide. Studies have shown that various factors cause these overruns. One of the critical factors that cause these overruns is poor communication. This study aims to study and measure the severity of poor communication in causing cost and time overruns in construction projects. The study adopted two consecutive approaches to study the effect of poor communication in causing cost and time overruns. The first approach was to conduct an extensive literature review to extract causative factors from diverse construction industries that consider poor communication as a causative factor, then to determine its severity percentage, among other factors for each study. From the analysis, it can be concluded that developed countries that apply information communication technology and advanced communication systems have lower severity percentages compared to other countries. The second approach was to conduct a qualitative study by interviewing construction experts and to examine their comments and criticisms of the results obtained from the literature. Experts were asked to highlight their views on the severity of poor communication in the construction industry. The outcome of these interviews was thematically analysed. The findings show that poor communication has a significant effect on cost and time overruns in construction projects.