Ahmed S.N, Pasquire C., and Manu, E. (2018). "Evaluating why quantity surveyors conflict with collaborative project delivery system" In: Proc. 26 th Annual Conference of the International. Group for Lean Construction (IGLC), González, V.A. (ed.), Chennai, India, pp. 1272-1282 ABSTRACTThe recurring poor performance and lack of collaborative culture in the UK construction industry has been a topic of debate for many years now. This has triggered an industry wide demand for performance improvement and innovation in the construction sector. Several studies over the years have reported and linked these concerns to fragmentation, deep-seated cultural resistance and negative commercial behaviours among project participants. Traditionally, Quantity Surveyors (QSs) within the UK system are popularly known for their commercial management functions i.e., contract advice and cost related roles. But, the lack of evidence on collaborative practice across the commercial roles often performed by the QSs in practice has revealed a separation within the construction model where QSs are formulated outside the core project production team (client, designers, and constructors). This continues with further practical implications like process waste, value loss, conflicts among others. However, recently, there were calls for industry-wide modernisation with an appeal specifically on QSs to create positive link within the value chain as against being a burden to it. Based on a literature review and a case study approach, the study further discovered other commercial factors deterring collaborative practice that is emanating from QSs position outside the production system. These factors among others are: commercial background &training, customer &safeguarding practice, excessive monthly reporting & commercial governance and balancing standards with innovation.