|This article does not cite any references or sources. (February 2011)|
Roof shingles are a roof covering consisting of individual overlapping elements. These elements are typically flat rectangular shapes laid in rows from the bottom edge of the roof up, with each successive higher row overlapping the joints in the row below. Historically, at the roof ridge there was a cap consisting of copper or lead sheeting which in modern times has been replaced by shingles with a plastic underlay.
Shingles have been made of various materials such as wood, slate, asbestos-cement, bitumen-soaked paper covered with aggregate (asphalt shingle), composite or ceramic. Due to increased fire hazard, wood shingles and paper-based asphalt shingles have become less common than fiberglass-based asphalt shingles.
Aging of shingles
The protective nature of paper and fiberglass asphalt shingles primarily comes from the long-chain petroleum hydrocarbons, while wood shingles are protected by natural oils in the cellulose structure. Over time in the hot sun, these oils soften and when rain falls the oils are gradually washed out of the shingles. During rain, more water is channeled along eaves and complex rooflines, and these are subsequently more prone to erosion than other areas.
Eventually the loss of the oils causes asphalt shingle fibers to shrink and wood shingles to rot, exposing the nail heads under the shingles. Once the nail heads are exposed, water running down the roof can seep into the building around the nail shank, resulting in rotting of underlying roof building materials and causing moisture damage to ceilings and paint inside.
A shingle is different from a tile:
- A tile is made of a ceramic material and is hard and brittle, poorly suited for places where tree limbs can fall on a house's roof, but not subject to deterioration due to rotting.
- A traditional shingle is made of wood. Roofing material made of more modern material (e.g., asphalt composition, asbestos) is sometimes referred to as "shingles".
While tiles tend to last much longer than wood or asphalt shingles, they are brittle and prone to fracture. Walking on tiles can break them, requiring replacement or the roof will begin to leak.
In the United States, fiberglass-based asphalt shingles are by far the most common roofing material used for residential roofing applications. The use of wooden roof shingles has existed in parts of the world with a long tradition of wooden buildings, especially Scandinavia, and Central and Eastern Europe. Nearly all the houses and buildings in colonial Chiloé were built with wood, and roof shingles were extensively employed in Chilota architecture. Roof shingles of Fitzroya came to be used as money and called "Real de Alerce".