Claims and, as a result, disputes have become one of the inherent attributes of construction industry. Most projects’ stakeholders know claims as the most destructive events in this industry. There are some possibilities of claims occurrence by both contract sides, especially contractors in most of the projects with different project delivery systems. Although it is not possible to eliminate the possibility of claims, the occurrence of claims in the projects can be prevented by identifying their main origins and causes. Data collection in this study was done, through organized study and semi-structured interview with experts and also the consideration of related documents that led us to reach 400 relevant cases for claims in Design-Build projects. After analysis of these cases by the researchers, the model of claim package was developed, which represents the fourth part of the claims. Then, the factors associated with each of the four parts were identified. First section contains the 48 most important claim origins. The second section includes 43 causes of claims. The third section includes 4 types of claims, and the fourth one includes 6 types of claim request. Then the forth part of the claim package model was distributed among the experts by closed questionnaire, and the most important cases of each part were identified. The identification of these claims can be useful in predicting future claims, and minimizing their effects in the similar ones.