This master's thesis presents the research results of new construction organization - lean construction. The main its goal is the detection of all possible losses during execution of works, analysis of their appearance causes and subsequent decreasing of their influence or elimination. In most cases the introduction of concept is performed only on separate sites and immediately prior to the beginning of works production, often only within individual projects, but not the whole production system. Therefore it is necessary to provide a system that will allow identifying losses at the pre-investment phase, that paving actions to mitigate losses or to eliminate them even before the beginning of the project, to develop organizational measures for the improvement of production indicators and to identify all deficiencies in work organization. For this purpose the assessment of losses has been proposed arising from the point of risk management view and loss control system has been developed at building site.