A structural member for a window comprising two extrusions spaced apart and coupled to each other using an insulating coupler extending at least 40 mm apart to form the structural member and hinder thermal bridging. A stiffener extends inside the structural member between the extrusions to stiffen the structural member and comprises two spaced apart ends engaged with the two extrusions, respectively. The two ends are coupled to each other using an insulating stiffener coupler to support the stiffener and hinder thermal bridging. A method of forming a thermally broken structural member.