Roof shingles on a residential home or commercial multi-family building are a roof covering consisting of individual overlapping elements. These elements are typically flat, rectangular shapes laid in courses from the bottom edge of the roof up, with each successive course overlapping the joints below. Shingles are made of various materials such as wood, slate, flagstone, cedar, metal, plastic, and composite material such as asphalt shingles. Asphalt shingles are the most commonly used. The two styles are Architectural or dimensional shingles and older style“3-tab” shingles. Architectural shingles are most commonly used due to the cost, how they look and perform over time.