This paper outlines the research area of new heat-insulating materials useful for the production of sandwich plate for building isothermal bodies. It also presents the inappropriate solutions of construction nodes causing the occurrence of heat leakage bridges, and thus the increase of the value of overall heat-transfer coefficient (of the whole body). The last part of the paper presents the advancement procedure for the prototype isothermal body. Information obtained on the basis of the analysis of the thermovision photographs (as well as local measurements of heat-transfer coefficient values) is very important for this procedure. The presented information is connected with the realisation of the research project PBS1/B6/6/2012 “Elaboration of production technology for complete semi-trailer for food transport in refrigeration conditions of improved technological parameters” (a leader - the firm Wielton from Wielun, consortium members: Poznań University of Technology and Industrial Institute of Agricultural Machines in Poznan [2]).