A relatively usual way to thermally insulate the external walls of a building is to apply it on the gap of a double-shelled walling. In this case, the inner brick wall will absorb the thermal energy due to the intermediate thermal insulation and it will gradually reflect it in the interior space when heating stops. Thus, the interior temperature is maintained for longer periods and the thermal comfort of the interior space is increased. However, it is worth noting that in the case of double walling there can’t be a complete elimination of thermal bridging. This can be achieved by installing an external thermal insulation system.
It is very likely that a double walling traps humidity which is not necessarily due to rainwater that penetrated the outer shell. It may be due to the temperature difference between the inner and outer wall or the transudation of vapor through the material. For this, the sealant must be resistant to humidity absorption. The ideal product for this case is STYROPAN XPS WALL. The boards' dimensions are 250 cm x 60 cm and their final surface is smooth (with the extrusion skin).
Indicatively, the double walling construction line of work is the following: