Asphalt Composite Shingles, What are asphalt composite shingles
Asphalt Composite Shingles speaks to what are asphalt composite shingles and why use asphalt composite shingles.
They are die cut from heavy sheets of asphalt impregnated felt faced with mineral granules that act as a wearing layer and decorative finish.
Most felts are based on glass fibers, but some still retain the older cellulose composition. The most common type of asphalt shingle, which covers probably 90 percent of the single family houses in North America, is 12 inches by 36 inches (305 mm by 914 mm) in size. There is also a metric shingle 337 mm by 1000 mm which is widely marketed.
In the most popular pattern, each shingle is slotted twice to produce a roof that looks as though it were made of smaller shingles. Other sizes and many other styles are available, including thicker shingles that are laminated from several layers of material. Asphalt shingles are low cost to purchase, quick to install, moderately fire resistant and have a life expectancy of 15 to 25 years depending on climate and their composition.
The same sheet material from which asphalt shingles are cut is also manufactured in rolls 3 ft (914 mm) wide as asphalt roll roofing. Roll roofing is very inexpensive and is used primarily on storage and agriculture buildings. Its chief drawbacks are that thermal expansion of the roofing or shrinkage of the wood deck can cause unsightly ridges to form in the roofing and that thermal contraction can tear it.
Roof Components:
Asphalt saturated felt paper.
Self sealing stripes which soften in the solar heat and bond the shingles together against wind uplift.
Note, each successive course starts with a shingle cut ½ tab shorter than the first shingle in the course below, to allow to stagger the slots from one course to the next.
The starter course has its tabs cut off to maintain a uniform thickness of roofing. It provides a waterproof layer under the slots in the first course of shingles.
Metal drip edge supports the projecting edge of the shingles and forces water to drip clear of the facia.
Considerations for Asphalt Composite Shingles:
When installing asphalt shingles, to give a finer visual scale to the roof, the slots make each shingle appear to be three smaller shingles when the roof is finished. Many different patterns of asphalt shingles are available including ones that do not have slots.
To start an asphalt shingle roof, building codes require the installation of an ice barrier beneath the shingles along the eave in regions with cold winters prone to ice damming. Where required, the ice barrier would replace the lowest course of asphalt saturated felt paper.
To complete an asphalt single roof a metal or plastic ridge vent strip is often substituted for the shingle tabs on the ridge to provide an outlet for ventilation under the roof sheathing.
A valley is formed in a roof where two sloping roof planes meet above an inside corner of the building.
There are three alternative methods of making a valley in an asphalt shingle roof:
The open valley uses a sheet metal flashing and the ridge in the middle of the flashing helps prevent water that is coming off one slope from washing up under the shingles on the opposite slope.
The woven valley and cut valley are the favourites of roofing contractors because they require no sheet metal, The solid black areas on shingles in the open and cut valleys indicate areas to which asphaltic roofing cement is applied to adhere shingles to each other.
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