Guide to Fiberglass Shingle Roofs
By Michael R Slattery
"Roofer Mike" breaks down fiberglass shingle roofs for the benefit of homeowners. Shingle variety, durability, aesthetics, energy efficiency and more are covered by one of the best residential roofing contractors in Miami.
Fiberglass shingle roofs are, by far, the most common system found on American homes today and an affordable, attractive, fire rated option for homeowners. When incorporated into a well-designed application featuring Cool Roof concepts, fiberglass shingles compare favorably with more expensive systems when considering energy efficiency and durability.
Certainteed, Atlas, GAF and Owens Corning are among the most popular shingle manufacturers and offer a variety of styles, colors and price ranges. Three-tab shingles, with their basic flat design, are an economical choice while dimensional shingles are an upgrade with stronger laminated construction and a layered look. Thicker architectural and designer shingles are high end options with a myriad of styles. Most three-tabs are rated for winds of up to 60 miles per hour, while some architectural and designer shingles can endure up to 135 mph.
Today's shingles are basically a fiberglass mat coated with hot asphalt. After cooling, ceramic granules are embedded in the asphalt for aesthetics and protection from the sun. Then an asphalt strip is applied slightly above the exposed portion of the shingle, adhering itself to the next when installed, enhancing wind resistance. All shingle systems rely on their lapped configuration to shed water as it flows over them. This restricts their use to roofs with adequate pitch. Rain water will accumulate and infiltrate the shingles when installed on a substrate without proper pitch.
Experienced roofers develop preferences for some shingle manufacturer's products over others. They'll notice subtle differences after several years of installations. For instance, close inspection of different manufacturers' white shingles show that their granules are mostly white with a sprinkling of black and gray. One company also incorporates just a few tan, brown, green and blue granules into the mix. Their shingles match the paint on homes better because while the beholder is not aware of the blend, their eye sees it. Another example is the difference in performance of the asphalt strip bonding the shingles. All strips perform well on hot sunny days but one company's shingles adhere fairly well under cool, cloudy conditions such as are present during storms.
The life cycle of a fiberglass shingle roof depends on its locale, reflective capability and the ventilation capacity of the system's design. While most people attribute a shingle's deterioration to sun and rain, thermal shock is the main cause of material failure. Over time, thermal shock causes cracks and splits in materials due to constant expansion and contraction during significant temperature changes. These effects can be minimized by the utilization of an adequate ventilation system and reflective material. These tried and true practices are effective anywhere but are most beneficial in warmer areas such as the Miami roofing market.
A well ventilated system using light colored shingles extends the roof's life cycle while cutting energy costs. Light colored shingles reflect the sun's rays while darker shingles tend to absorb them. Effective roof ventilation systems have an intake mechanism at the eaves and an outflow capability near the peak. Most homes have soffit vents at the eaves of the roof but many have no outflow component. This creates a system requiring wind to create any appreciable airflow and is not ideal for summer. An outflow component must be installed at or near the peak of the roof to allow hot air to escape, lowering temperatures in the attic. This is the practical application of a basic law of physics: hot air rises. Gable vents, ridge vents, turbine ventilators and power vents are all effective outflow accessories for an efficient system.
When Cool Roof concepts are incorporated into the design, fiberglass shingle roofs can be a viable option.