Recently, there have been increasing studies on the application of digital technology, which has its focus of the irregular building. However, most of these studies have not clarified the objective of the technology and the effectiveness of professional manpower on its performance. This study analyzes actual used technology and the role of specialty contractor. It presents a framework to quantify the performance of the specialty contractor. For these purposes, this paper presents a proposed method to evaluate the activities of specialty contractors using a queueing model. As an attempt to verify the model, an actual irregular building project, in which digital fabrication is applied, is investigated during the construction phase. In order to collect the digital fabrication data, digital fabrication reports and specialty contractor's work log of project are reviewed. In addition, Digital Fabrication input personnel, productivity data are collected through interviews with experts involving in the case project. Analysis of specialty contractor's performance in digital fabrication reveals that the wait status of project participants varies probabilistically depending on the digital technology application level. The results of this study are expected to contribute toward the improvement of the production level in the construction industry.