Recently, the existing estimating system for public construction projects is facing a major change in Korea, Product-based modelling techniques which are widely used in the UK are being considered to replace the existing system which is based on process-based techniques. Therefore, it is important to achieve a clear understanding of the theoritical context of product-based techniqes, that is, cost modelling. In addition, it is also crucial to examine UK's experience so as to identify advantages and drawbacks in current cost modelling practice. The objective of this paper is to examine some fundamental issues in cost modelling for building projects in order to bring a better understanding of the context of product-based techniqes. Further-more, it is to discuss the current trend of research regarding the development of cost modelling techniques.