Quite often during the process of facilities construction the contractors change and unreasonably deviate from engineering solutions specified in the design documentation. Design institute performs design supervision exactly for the purpose of full accordance of design concept with investment one. After all, quite often additional issues and updates occur during the process of facilities construction and prompt reaction is essential. Urgently required changes in design documentation are not excluded due to the corrections and additional requests of the customer that arose at the stage of construction or approval of equipment or material change due to a number of reasons that may include possible phasing out of one of the components by manufacturer. Reasons according to which the participation of design organisation is required on site not only in full compliance with the project, but also in the fact that the customer or investor that entrusted the design company with the development of technical documentation during the construction process under the constraints of circumstances related to contractors or suppliers diminish its demands. This is more likely to occur during construction of increased complexity facilities or under severe climatic conditions. It is design developer who can adequately justify and protect the purposes of customer to create safe, technically correct in details buildings or constructions. Control from behalf of the design developer ensures the compliance with the requirements of design and regulatory documentation.