Stiffeners are disclosed which can be added to the header section of cast light-metal door panels. The header section casting can be designed for manufacturability, and to meet nominal lateral stiffness specifications while making effective use of material. The stiffeners can be cast in place in the header or attached to the header section after casting via snap-fit features, adhesive or both. The stiffeners can themselves be made of a light-weight metal such as aluminum, and can be produced by roll forming, stamping or extrusion. By effectively yielding a closed-section door header shape, the stiffeners provide maximum incremental bending stiffness in the header while adding a minimum amount of incremental material and mass.
 This invention was made with U.S. Government support under Agreement No. DE-EE0005753 awarded by the U.S. Department of Energy. The U.S. Government may have certain rights in this invention.