Asphalt shingle

An asphalt shingle is a type of wall or roof shingle that uses asphalt for waterproofing. It is one of the most widely used roofing covers in North America because it has a relatively inexpensive up-front cost and is fairly simple to install. Asphalt shingles are an American invention by Henry Reynolds of Grand Rapids, Michigan. They were first used in 1903, in general use in parts of America by 1911 and by 1939 11 million squares of shingles were being produced. A U.S. National Board of Fire Underwriters campaign to eliminate the use of wood shingles on roofs was a contributing factor in the growth in popularity of asphalt shingles during the 1920s. The forerunner of these shingles was first developed in 1893 and called asphalt prepared roofing which was similar to asphalt roll roofing without the surface granules. In 1897 slate granules were added to the surface to make the material more durable. Types of granules tested have included mica, oyster shells, slate, dolomite, fly-ash, silica and clay. In 1901 this material was first cut into strips for use as one-tab and multi-tab shingles. All shingles were organic at first with the base material, called felt, being primarily cotton rag until the 1920s when cotton rag became more expensive and alternative materials were used. Other organic materials used as the felt included wool, jute or manila, and wood pulp. In 1926 the Asphalt Shingle and Research Institute with the National Bureau of Standards tested 22 types of experimental felts and found no significant differences in performance. In the 1950s self-sealing and manually applied adhesives began to be used to help prevent wind damage to shingle roofs. The design standard was for the self-sealing strips of adhesive to be fully adhered after sixteen hours at . Also in the 1950s testing on the use of staples rather than roofing nails was carried out showing they could perform as well as nails but with six staples compared with four nails.