عنوان مقاله [English]
The construction industry is a large part of Iran's economy. A considerable amount of national resources, including energy and materials, are consumed in this sector. Therefore, the efficiency of this industry has an essential role in the sustainable development of the country. Cost overruns of construction projects or deviating from the budget is one of the most influential factors in reducing the efficiency of this industry and the occurrence of numerous problems in it. Therefore, accurate knowledge of the reasons for the deviation of costs from the planned budget is a significant factor in managing the cost of construction projects. In this paper, a review of similar research conducted and a long list of reasons for cost deviation was prepared. Then, based on the ecology of Iran's construction industry, this list was modified, completed, and categorized. The list has been distributed as a questionnaire among 230 experts, and the severity and frequency of each factor were asked. Based on the obtained data, statistical analyzes such as ANOVA were performed. According to the results, inflation, project prolongation, slow administrative processes, inadequate resource planning, and low efficiency and reprocessing due to incorrect or non-integrated design in various fields are among the most critical factors causing increased costs and deviation from the budget plan.