The thesis deals with the topic of building orders are how they are managed by contracting authority or client. It presents building order as a project, and describes the way in which this project is organized, prepared and implemented. It also highlights all the factors that have impact on how building orders are managed. And since the most important of these factors is construction costs, the thesis provides an analysis of one particular building order from this perspective, listing all the things that are involved in the construction costs and pointing out in what way. The accuracy of the expected costs is then compared with construction engineering price indicators.