Background Residential investment projects play a vital economic and social role in Iraq; however, delays are a persistent problem that negatively affects project performance. Identifying and prioritizing the main causes of delay is challenging due to uncertainty and differences in expert judgment. Therefore, a systematic quantitative approach is required to evaluate these causes and their associated risks. Methods This study aimed to identify, classify, and prioritize the causes of delay in residential investment projects in Iraq. A questionnaire survey was conducted with experts specializing in residential projects. Fifteen main delay causes were identified and grouped into three categories: general causes, project parties–related causes, and resource-related causes. The Fuzzy Analytic Hierarchy Process was applied to determine the relative importance weights of the delay causes under uncertainty. The degree of delay risk for each cause was calculated by combining its relative weight with the probability of occurrence and impact. Results The results indicated that, within the general causes category, management-related and political causes were the most significant, each accounting for 14.6%. In the project parties–related category, owner-related causes had the highest importance, with a relative weight of 50.6%. For the resource-related category, labor-related causes were found to be the most influential, with a relative importance of 61.2%. The risk assessment highlighted variations in delay severity depending on both uncertainty and impact levels. Conclusions The findings demonstrate the effectiveness of the Fuzzy Analytic Hierarchy Process in prioritizing delay causes under uncertainty in residential investment projects. The proposed framework supports decision-makers in identifying critical delay factors, improving risk management, and reducing delays in future residential projects in Iraq.
Hasan et al. (2026) studied this question.