Risks pertaining to construction work relate to situations in which various events may randomly change the duration and cost of the project or worsen its quality. Because of possible significant changes of random events, favorable, moderate, and difficult conditions of construction work are considered. It is the first stage of the construction risk analysis. The probabilistic parameters of construction are identified and described by using the design characteristics model of the structure and the construction technology model. The first describes the probabilistic properties of the structure execution's technology. The second describes the probabilistic properties of the works execution. Both models contain basic probabilistic data for scheduling, cost estimating, and risk assessment of the construction.