Building information modeling (BIM) is a major upheaval in construction industry. Although BIM advantages in construction management has been proved in many papers reviewed, there are still many limitations that inhibit organizations to use BIM models efficiently. However, advancement of application programming interface (API) in the recent years has facilitated employing BIM in construction industry. This research contributes to the state of practice in construction management by developing API codes to automate estimation of construction. The developed API automatically filters items related to a particular discipline within a particular work area and facilitate systematical quantity take off in different work areas. This allows the planner to define proper 3D work areas and to estimate the required materials and man-hours in different work areas throughout the project. The results of the developed automated approach are compared with hand calculated results as well as the results calculated from the BIM software interface in special cases. Finally, the research has been validated by a case study of an actual petrochemical project.