BACKGROUND OF THE INVENTION
Asphalt roofing products are often divided into three broad groups: shingles, roll roofing and underlayment. Shingles and roll roofing typically functions as outer roof coverings designed to withstand exposure to weather and the elements. Shingles and roll roofing generally contain the same basic components which provide protection and long term wear associated with asphalt roofing products. These components include a base material made from an organic felt or fiberglass mat which serves as a matrix to support the other components and gives the product the required strength to withstand manufacturing, handling, installation and service in the intended environment. An asphalt coating formulated for the particular service application is often applied to the base material to provide the desired long term ability to resist weathering and to provide stability under the anticipated temperature extremes. An outer layer of mineral granules is also commonly applied to the asphalt coating to form a surface exposed to the weather which shields the asphalt coating from the sun’s rays, adds color to the final product and provides fire resistance.
Asphalt shingles are one of the most commonly used roofing materials. Such shingles are typically manufactured as strip shingles, interlocking shingles and large individual shingles in a variety of weights and colors. Such asphalt shingles are also often referred to as composite shingles. Even though composite and/or asphalt shingles offer significant cost, service life and flammability advantages over wood shingles, wood shingles are still often preferred due to the pleasing aesthetic appearance of a wood shingled roof. An important aesthetic advantage of such wood shingles is their greater thickness as compared to composite shingles. The thickness of wood shingles results in a more pleasing, layered look for the finished roof.
Various composite shingles have been developed to provide an appearance of thickness comparable to wood shingles. Examples of such composite or asphalt shingles are shown in U.S. Pat. No. 5,232,530 entitled Method of Making a Thick Shingle; U.S. Pat. No. 3,921,358 entitled Composite Shingle; U.S. Pat. No. 4,717,614 entitled Asphalt Shingle; and design and U.S. Pat. No. D309,027 entitled Tab Portion of a Shingle. These above-referenced patents are incorporated by reference for all purposes within this application. Also, the Residential Asphalt Roofing Manual published by the Asphalt Roofing Manufacturers Association provides excellent information on various types of shingles and other roofing products.