PURPOSE: To improve appearance without exposing piping such as a water supply pipe, a hot water supply pipe and a drain pipe by housing the piping within a wainscot panel wall having internal space.

CONSTITUTION: A wainscot panel wall 1 having internal space is formed out of a top plate 1a and a wainscot lb, and longitudinal space 1c is formed between wall surface 2 and the wainscot 1b. A row of a water supply pipe 4, a hot water supply pipe 5 and a drain pipe 6 laid in vertical order from an upper level to a lower level, is provided in the space 1c. In this case, the height of the top plate la of the wall 1 from a floor 3 is pertinently selected, depending upon a purpose. Also, the projection size of the wall 1 from the wall surface 2 is selected to suit a range capable of housing the pipes 4 to 6 with an allowance, and in consideration of interior functionality as a wainscot. According to this construction, appearance becomes neat without exposing the piping, and each type of piping can be laid at such a place as conventionally refusing the arrangement thereof.