Asphalt shingle
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An asphalt shingle is a type of roof shingle. They are one of the most widely used roofing covers due to the fact that they are relatively inexpensive and fairly simple to install.
[edit] Types of Asphalt Shingles
Two types of asphalt shingles are used: organic and fiberglass or glass fiber. Organic shingles are generally paper (felt) saturated with asphalt to make it waterproof, then a top coating of adhesive asphalt is applied and the ceramic granules are then embedded. A portion of the granules contain leachable copper or more often tin to prevent moss growth on the roof. Organic shingles contain around 40% more asphalt per square (100 sq. ft.) than fiberglass shingles which makes them weigh more and gives them excellent durability and blow-off resistance. Shingles are judged by weight per square.
Fiberglass shingles have a glass fiber reinforcing mat manufactured to the shape of the shingle. The mat is then coated with asphalt which contains mineral fillers. The glass fiber mat is not waterproof by itself and is a wet laid fiberglass mat bonded with urea-formaldehyde resin. It's used for reinforcement. The asphalt makes the fiberglass shingle waterproof. Fiberglass reinforcement was devised as the replacement for asbestos paper reinforcement of roofing shingles and typically ranges from 1.8 to 2.3 pounds/square. The older asbestos versions were actually more durable and were harder to tear, an important property when considering wind lift of shingles in heavy storms. Fiberglass is slowly replacing felt reinforcement in Canada and has replaced mostly all in the United States. Widespread hurricane damage in Florida during the 1990's prompted the industry to adhere to a 1700 gram tear value on finished asphalt shingles.
Shingles are ranked by waranteed life, ranging from 25 to 50 years. A newer design of asphalt shingle, called laminated, uses two distinct layers and is heavier, more expensive and more durable than traditional designs. Laminated shingles also give a more 3-D effect to a roof surface.
[edit] Durability
Asphalt shingles usually last longer in cooler climates than warmer ones. Thermal shock is one thing that is damaging to shingles (thermal shock is what roofing materials experience when the ambient temperature changes dramatically within a very short period of time). Another factor affecting asphalt shingle roofs is attic ventilation. Proper roof ventilation has been known to extend the service life of a roof. Shingles should not be applied during cold weather. Each shingle must seal to the layer below it to form a monolithic structure. Sun and heat to soften the underlying exposed asphalt is a requirement during the initial phase of a new roof. Staple guns should not be used on shingles because they tear into the substrate too easily. Traditional roofing nails remain the best method of applying shingles.
