The extension panel system W653.de is designed with a substructure made of sheet steel profiles CW 75/100 as a single column freestanding in front of the base wall. The cladding with solid panels is horizontal and single-layer. Due to the free-standing design arbitrarily large wall cavities can be realized, there is no dependence on the strength of the base wall. With the cladding made of solid construction boards, requirements for sound insulation and robustness can be met in one layer and stand spacing of up to 1000 mm is possible.