Humidity-related behavior of internal thermal insulation systems with high insulation thickness – Evaluation of a three-year monitoring of various internal thermal insulation systems with high thermal resistances. Increased thermal insulation thicknesses of an internal thermal insulation system have been associated with an increased amount of condensation within the boundary layer between the insulation material and the external wall construction. Influenced by the well-known Glaser method only vapor diffusion is considered. The real vapor transport and storage behavior of an internal insulated external wall is much more complex. A three-year monitoring of various internal thermal insulation systems with high layer thicknesses refutes the mentioned prejudice. The case of sufficient driving rain protection, no condensation could be detected within the construction. Due to different behavior of the insulation properties and the diffusion resistance with respect to the thickness of the insulation material as well as the considered storage capacity of water vapor in the building materials leads to a possible reduction of the precipitated condensation. Higher insulation standards seem to be possible.