The purpose of this paper is to examine the possibility of applying non-structural fuzzy decision support theory in modelling the negotiation between various participants with conflicting objectives so as to establish the optimum buffer stocks for a construction project. In view of the divergence in objectives between various decision makers when determining the amount of materials to be delivered to site, the concept of integrating the non-structural fuzzy decision support system (NFDSS) to multi-attribute decision making is reviewed. With the help of a case study example, the process involved in the NFDSS and the methodology of evaluation are illustrated. Finally, the paper proposes the use of the Nash criterion to measure the utility of various decision makers so as to identify an equilibrium solution on the quantity of materials to be supplied. The results indicate that the requisite number of on-site stocks can be determined by referring to the utility of the parties involved in decision making. The NFDSS systematically evaluates each scenario under different affected factors such as cost, schedule, quality, safety, etc. Finally, a scenario utility is computed to establish the preference of each party. The paper is of value in showing how NFDSS can systematically analyse human judgements to generate relative weightings for the decision factors and elements. The NFDSS model can be applied to real-world cases to determine the frequency of delivery and the amount of buffer stocks that would meet the interest of various project participants.