the mpc base flange 148 flush with end outside corner of wall 2 212 the mpc base flange 148 of a second multi purpose channel 118 is positioned up against the mpc base flange 148 of the first multi purpose channel with the two base flanges coincident but the wire chase area not coincident this arrangement provides a corner support for a plurality of rigid foam panels 120 to be installed later the installation of an insulated wall system around windows and doors follows similar steps as above and in the parent application fig1 illustrates the first steps for installing an insulated wall system 200 around window openings and door openings fig1 illustrates an existing window opening 204 on wall 2 212 the first steps are to prepare the upper and lower horizontal edges of the window opening 204 with the installation of a pair multi purpose channels 118 the upper horizontal edge of the window opening 204 has a first multi purpose channel 118 installed sued that its mpc base flange 148 is positioned against wall 2 212 such that an open side of the mpc support leg 150 is facing downward and the mpc exterior rigid insulation support flange 154 and the interior rigid insulation support flange 152 are facing upward to support a rigid insulation foam panel 120 the lower horizontal edge of the window opening has a second multi purpose channel 118 installed such that its base flange.