The subject of this paper is the analysis and evaluation of the reasons for construction costs increases in urban regeneration projects. The analysis considers major refurbishments of real estates’, as well as heavy repair and modernization of the road system. For the period mentioned, the costs from works and expenditure schedules were compared with the costs of additional works, which shows the percentage cost increase in relation to initial project budget assumptions of the case study. The analysis revealed that due to difficulties in assessing technical state of inhabited buildings, the investor and potential contractor should pay special attention to the character of issues presented in this paper, taking into account an increased risk of their occurrence.