A method of installing an insulation system proximate a jamb having steps of: providing a stud member adjacent an opening in a wall; providing and positioning an angle jamb member having a front panel portion and a side panel portion; providing a plurality of spaced apart bracket members; positioning and attaching at least one of the bracket members in a substantially parallel orientation relative to the stud member; and positioning each of a plurality of insulation panels between the at least one bracket member and the angle jamb, while being spaced apart therefrom.