The economic crisis in 2008 has changed the perspective of investors to risk management. Uncertainty and incomplete information play an important role in risk assessment of investments. In this paper, an integrated risk assessment approach has been proposed. The proposed methodology consists of fuzzy information axiom, fuzzy analytic hierarchy processes (AHP), and an aggregating algorithm to satisfy group decision. The application of fuzzy information axiom methodology is used to take into account the uncertainties and the subjective preferences in the complex problem while fuzzy AHP is used to take into consideration the effects of the risk factors. The proposed methodology allows decision makers to evaluate risk factors by using linguistic terms rather than precise numerical values. Finally, proposed methodology is applied for risk assessment of renovation and retrofitting project of public buildings in Istanbul.