Roll-up coverings for architectural openings and related methods, systems and devices

A fabric panel for a roll-up window covering, the fabric panel comprising:

• a plurality of assembled strips of material joined together, each assembled strip of fabric material including:
• a fabric material including an inner surface, an outer surface, a top end, a bottom end, a first side edge, a second side edge, the outer surface defining a first contact surface adjacent to the top end of the fabric material, the bottom end of the fabric material being folded over to define a first folded piece of fabric of said fabric material defining a second contact surface;
• and
• a stiffener including an inner surface and an outer surface,
• wherein the inner surface of said stiffener is adhered to the first contact surface of a first assembled strip of fabric material and said outer surface of said stiffener is adhered to the second contact surface of an adjoining second assembled strip of fabric material such that said stiffener is positioned directly between the first contact surface of the first assembled strip of fabric material and the second contact surface of the adjoining second assembled strip of fabric material.