Double-shell walling

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.

double-shelled walling insulation


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).

Alternatively, expanded polystyrene boards (white or graphite) can be used, ideally EPS 80 class or more.

Indicatively, the double walling construction line of work is the following:

  1. First wall construction up to the height of the chainage.
  2. Installation of the first line of STYROPAN XPS WALL thermal insulation boards. Special stainless sockets (6 sockets / m2) can be used for support. The board connections must be performed in a way that the standing seams on the board sides do not allow humidity to pass through from the outer wall.
  3. Installation of the second line of STYROPAN XPS WALL boards up to the chainage level.
  4. Second wall construction up to the height of the chainage.
  5. Chainage construction and installation of STYROPAN XPS WS extruded polystyrene on one side. This will significantly reduce thermal bridging over the chainage
  6. Repetition of the steps above until the wall is completed.