There are two types of asphalt roofing materials: organic and inorganic. Together they account for about eighty percent of the roofing materials sold in the United States. Both organic and inorganic asphalt shingles are constructed from a base mat which is covered in asphalt and finely crushed mineral granules. Organic asphalt shingles have base mats of wooden chips, cellulose fibers, or recycled cardboard, while inorganic ones are made of fiberglass.
Inorganic asphalt shingles are both stronger and more fire-resistant than organic ones, but the organic shingles are simpler to install and are better able to withstand extreme cold and high wind without tearing. Some makers of inorganic asphalt shingles will bind them with a polymer-based asphalt to add to their cold and wind tolerance.
In spite of their name and appearance, asphalt shingles are seldom installed as individual shingles but usually as sheets of shingles, both to save on labor costs and to reduce the risk of leaking.
Metal Roofing Materials
While their similar appearances may make it difficult for most of us to distinguish among the different types of metal roofing materials, the five metals from which they can be made give them widely ranging characteristics. The metal most often used in metal roofing materials, because of its strength and durability, is steel. But untreated steel is susceptible to corrosion and rust, so most steel metal roofing materials have a protective coating of tin.
In addition to being treated with tin, most steel roofing will some sort of decorative coating to improve its appearance. Stainless steel is also used in roofing because of both its striking appearance and its resistance to rust and corrosion, but is rare because it is so costly.
Aluminum, after steel, is the most popular metal roofing material for homes, but must be painted to make it presentable. Aluminum is both lightweight and impervious to rust, but is usually coated in he same way as steel roofing.
Copper and Alloys
Copper is the most expensive of all the metal roofing materials, but requires no treatment because it is naturally rust and scratch resistant. Copper is also one of the most beautiful of roofing materials, with its glowing red sheen gradually taking on a lovely green patina as the years pass. Copper roofing can last for more than a century if properly maintained.
Like copper, metal roofing materials roofing alloys are expensive, but they are also extremely strong, durable, and attractive. Their costs will vary depending on the different metals they contain.