The use of prefabricated structures and elements improves the quality and speed of construction. The sanitary module is a finished bathroom, combined with a toilet after this referred to as STM. It is a finished room with a supporting wall frame and base, completely finished. It has mounted utilities and plumbing fixtures. The object of the research is the STM base frame. Analysis of the scientific literature has shown that the study of the bearing capacity of the STM frame was not carried out. The object of research is based on the module structure. By literature review is demonstrated that there are no scientific researches of module structure base work in erection on site. Method of research. Basically, the numerically-analytical method is to be used for the analysis of structural behaviour. Results. Analysis of results of FEM calculations and on-site erection represent that the bearing capacity of the module base is ensured.