A fire risk computer model CUrisk is being developed at Carleton University to evaluate fire safety designs for four-story, timber-frame commercial buildings. The model consists of the system model and a number of subsidiary submodels. The system model implements the risk analysis framework and controls data flow of the submodels; it is also responsible for calculating the life hazard of each scenario. Other submodels include Fire Growth and Smoke Movement, Boundary Failure and Fire Spread, Occupant Response and Evacuation, and Building Cost and Economic Loss. Using the outputs of the submodels, the system model calculates three decision-making parameters, the Expected Risk to Life, the Expected Risk of Injury, and the Fire Cost Expectation. These parameters are based on possible fire scenarios and their associated probabilities. This paper provides a brief description of CUrisk, and presents the results of a multi-scenario risk analysis for a four story commercial building.