Asphalt Roof Coverings and Failure Mechanisms

The most common roof covering material found while performing New Jersey Home Inspections are asphalt shingles. Asphalt shingles are comprised of a base material made of fiberglass. An asphalt body or coating and surface granules. The felt or base material gives the shingle its strength. The asphalt component gives the roof shingle its ability to resist weathering and damage. The granular material protects the roof shingles from the rays of the sun and also produce the color of the shingle.

Asphalt roof coverings have a typical statistical life expectancy from fifteen to twenty years. Beware of those saying that life expectancy of asphalt roofs are longer then 25 years. You would be hard pressed to locate a roof still in useful condition that is more then twenty five years old. 

Manufacturing factors that play into the life expectancy of an asphalt roof are:

A. Shingle thickness- The thicker the roofing material the greater its life expectancy.
B. Color- Lighter color roofing materials tend to deflect sunlight rather then absorb it. As a result the lighter color roof coverings most likely will have a longer life expectancy then the darker color roofs.

Building and construction factors that can effect asphalt shingle life:

Slope of roof: Asphalt shingles should last longer on steep pitched roof systems because water sheds more easily and quickly, there should be no areas of pooling water. Almost flat roofing systems do not shed water away quickly and thus have a shorter life expectancy.

Sunlight: The more ultraviolet rays a roof covering receives the more it is likely to wear prematurely or have a shorter life expectancy. The roof covering not exposed to direct sunlight should have a greater life expectancy.

Ventilation: Ventilation plays a very important role in extending the life expectancy of an asphalt roof covering. Roofs with adequate and well placed ventilation should have a longer life expectancy then roofs with out proper ventilation. Ventilation allows the underside of the roof to be cooler thus prolonging roof life expectancy. Ventilation is usually accomplished by the installation of ridge vents, gable vents, soffit vents and attic vent fans.

Manufacturing defects: Defects that arise during the manufacturing process contribute to reduced life expectancy of roofing materials. One of the most prevalent defects in asphalt roof shingles causes thermal splitting. This is a defect in which the shingles crack through prematurely and have a much shorter life expectancy.

Adverse climates: Colder and wet climates will reduce the life expectancy of asphalt roof shingles. The more stable the outside environment the longer life the asphalt roof product should have. Harsh, colder environments will wear an asphalt roof out prematurely.

Asphalt shingle roof problems:

Thermal splitting (cracking): This defect is usually caused by the fiberglass mat in the asphalt shingle being too thin and thus becoming more susceptible to tearing. The bonding adhesive that prevents uplift may be too strong thus allowing one continuous flow of roofing without  the necessary room for some shingle movement. Both of theses manufacturing defects contribute to more roof shingle tearing and wear. When these types of defects exist in the shingles themselves any changes in climate conditions will adversely effect the life expectancy of the roof. 

Cupping: Asphalt shingles become lower in the center and raised at the ends, almost like a u-shape. Cupping is one of the signs of an old and worn asphalt shingle roof. Cupping is a normal wear pattern that progresses as the shingles get older. One aspect of a cupped roof surface is that it is very fragile and should not be walked on because significant damage can occur to the brittle roof shingles.

Granular loss: The job of the granular material is to help protect the roof shingle mat from the suns rays. The roof granules also give the roof covering its color. Some granular loss is normal and this can usually be seen as granules sitting in the bottom of the gutters. As the roof covering ages granular loss may become more several where ultimately areas of mat are fully exposed. Exposed areas of shingle mat will wear at a much faster rate because of the exposure to sunlight and other elements.

Curling: Another condition that is bought about by roof age. The roof shingles edges curl under as the roof gets older. As with a cupping roof the curing room is very brittle and should be replaced as soon as possible.

Expanded keyways/fish mouthing: This is a roof wear indicator where the area between the shingle tabs separates and is wider at the bottom of the shingle then the shingle top. Fish mouthing exists when the shingle above the keyways under it raise up and almost look like the open mouth of a fish. Fish mouthing is caused by higher then normal building moisture and less then adequate roof venting. Having this wear/defect tells us that a larger issue exists with in the dwelling as opposed to just normal shingle wear.

As part of your New Jersey home inspection we will be looking hard for roofing material age, wear and defects. After the home inspection you will know exactly what you can expect from the roofing material installed on your home.

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