For the purpose of the graduation thesis, a residential building was chosen as the default building. It is necessary to calculate the cost and time of building the building. The calculation was preceded by classifying the required works on the activity and calculating the amount through the measure proves. Once the calculated quantities have been calculated, time and resource requirements are calculated most likely to be the time of construction. Activities are linked by appropriate links and using the network diagram the total duration of the project is calculated. Using the PERT method and the predetermined most probable time, the expected project duration was calculated. The paper presents a comparison of the probability of execution of these two times. The probability of building construction for the most likely duration of activity is 88%, and the expected duration of activity is 45%. As most likely construction time is more likely to be executed, it has been taken as a legitimate one. The paper also presents the calculation of the costs of carrying out the building. Based on the obtained budget, an analysis of cost-effective significant activities was made. At the end of the operation the costs are shown in the S-curve time.