Because of the increasing regulatory requirements for heat-shielding properties of the exterior walls multi-layer building envelope became widespread. National practice of operation of multilayer outside walls revealed their increased defects, and first of all, this refers to the facing layer, usually performed with the stones with high voidage. Facing layer besides its aesthetic properties should reliably protect the internal structures from the negative environmental impact in the course of the operation period of a building. This can only be achieved through an analysis of its work (both the strength and heat engineering), which was often out of sight. The purpose of the study was to assess the possibility of further widespread use of stone masonry with a high voidage as the facing outer layer in Russia, and to identify the most efficient way to analyze the stress-strain state of the top layer. The foreign experience in using the hollow stones was considered, relevant strength and thermal engineering calculations were made. The conclusions on the renunciation of widespread application of stones of high voidage for lining multilayer walls and the possibility of using stones with not more than 15% range of hollowness were made. It was also concluded that the most reliable mode of deformation of the facing layer can be obtained from the joint strength and thermal calculations based on the results of monitoring of existing buildings, as well as field and laboratory tests.