Actual problem of architecture and construction is improvement of hygrothermal conditions of the modern building components with the increased thermal performance. The evaluation of hygrothermal performance of three-layered wall construction with outer layer from lining ceramic brick, with use insulated glass staple fiber products of the TS 034-Aquastatik brand of production of JSC KNAUF Insuleyshn is presented in the paper. Calculations are executed for two points — St. Petersburg and Kazan differing according to external climatic data and service conditions of the building components. Two options of calculation — with unventilated air gap and with the well-ventilated air gap located between a heat-insulation layer and an outer layer from lining ceramic brick are considered. For the purpose of an objective comparative assessment of hygrothermal conditions the design of external walls is accepted identical, with the same thickness of a heat-insulation layer (150 mm). It is shown that the external climate has impact on moisture conditions of external walls with unventilated air gap, creating a moisture gain in a design during moisture accumulation. Use in designs of external walls of a well-ventilated air gap allows to improve considerably moisture conditions of the building components in various moist and climatic zones and it is recommended for practical application.