Abstract: A "Wall Member" which comprises an elongated substantially rectangular extruded mono-shell defining an inner core, extruded in indefinite length, after which it is cut to the required dimension. The shell is made of low heat expandable material and contains an insulating material therein. The shell is formed with two vertical faces one of which having a permanent building exterior finish and the other having a permanent building interior finish. This interior vertical face is also provided within its main core, with an adjacent integral conduit therein for horizontal electrical leads. The shell is additionally formed with two horizontal upper and lower faces which are adapted for engagement over one another, such as by tongue and groove. These "Wall Members" are also adapted for connecting their ends which are provided with upper and lower hard surface fins to a structural vertical member such as a Post, window or door frames or another "Wall Member".