The foreign steel-aluminum sun rooms are mainly because some of them are too big. Because of the high strength of steel and convenient welding, steel frame and aluminum covered electrode are adopted. Build a big sun room. In China, because the sun room is a new thing, just emerging, and the price is high, in order to reduce the cost, steel-aluminum composite (steel as the main structure to meet the strength problem, and aluminum as the surface decoration, making the sun room durable and more beautiful.