A trapezoidal roof profile has a ribbed trapezoidal-shape pattern across the panel. This means, it is a quadrilateral (or a four-sided shape – see Figure 1) that has just a single pair of parallel sides. Sometimes, trapezoidal roofs are mistakenly referred to as corrugated. This is a misnomer as the corrugated profile has a repeating wavy pattern across its surface.Trapezoidal rib roofs are popular with producers because the shape makes them very material-efficient (a high strength-to weight ratio).