Quantity Take-Off Using Building Information Modeling (BIM), and Its Limiting Factors

Traditionally, quantity take-offs and estimates have been performed and developed with 2-D drawings supplied by the architect to the general contractor (GC). However, in recent years, the construction industry has seen a shift toward Building Information Modeling (BIM) and BIM-based quantity take-off (QTO). Although BIM has gained popularity in recent years, models supplied to general contractors often lack consistent quality that would allow the general contractor to extract data that would facilitate an appropriate quantity take-off and estimate.

General contractors were surveyed using on-line questionnaires and in-person interviews to determine factors limiting the ability of building professionals to extract the necessary quantity takeoff data from the model. Respondents were further asked to compare BIM-based QTO to traditional 2-D methods. Surveys and questionnaires were also used to determine which elements and items in models were typically included, inferred, or omitted.