Asphalt shingle roofs are the most popular type of residential roofing product used today. In fact, upwards of 80% of homeowners select asphalt shingles as their roofing material of choice. Asphalt shingle roofs are easy to maintain and replace, however installation is a tedious task best left to a roofing installation professional. Asphalt shingles have opened up many possibilities for homeowners looking to install quality, attractive roofing but stick within a budget. They are inexpensive to produce and basic styles can be installed for under $100 per square installed. One roofing square equals one hundred square feet, a 10’x10′ section.
Asphalt shingles are available in a wide range of solid and variegated colors which give homeowners many possible looks to choose from. Asphalt roofs designed to mimic the appearance of more expensive roofing options, such as slate roofs and tile roofs, offer budget-friendly choices in roofing material.
There are two distinct types of asphalt shingles: glass fiber shingles and organic shingles. Both types of asphalt shingles consist of a base material that has been coated with asphalt and embedded with ceramic granules. The asphalt makes the roofing material waterproof and the ceramic provides UV protection to the roof. The ceramic granules are also responsible for giving the shingles their various aesthetic styles.
The difference between glass fiber roof shingles and organic roof shingles is the base material. Glass fiber shingles (also referred to as fiber glass roof shingles) are constructed of a mat made of wet, randomly-laid sections of fiberglass that are bonded together with a special urea-formaldehyde resin. The asphalt coating, responsible for making the roofing material waterproof, will not stick directly to the fiberglass mat so mineral fillers are added to the asphalt, causing it to cling tightly to the fiberglass base mat. These type of asphalt roof shingles are typically given a Class A fire rating.
Organic shingles are made of a base mat of paper which is saturated with asphalt and then coated with the ceramic granules. Organic asphalt shingles are less fire-resistant than their glass fiber counterparts due to their paper base. They typically have a Class C fire rating, although some organic asphalt roof shingles have received a Class B rating. These shingles are heavier by roughly 40% than glass fiber asphalt shingles, which does make them very durable and resistant to blow-off.
Both organic and glass fiber asphalt roofing shingles are available with special coatings which help extend their useful life in certain climatic conditions. For roofs in hot, humid climates shingles are available that have been coated to resist algae growth. There are also shingles coated to increase strength and improve resistance to cold weather conditions which are useful for roofs on buildings where the freeze-thaw cycle is a problem.
Asphalt roofing shingles are available in a variety of styles and price points. Standard 3-tab shingles are the most basic style and the least expensive asphalt roofing material. A newer design of glass fiber shingle, called architectural or laminated shingles, use two separate layers to give an interesting visual effect. These higher-end asphalt shingles are sometimes called dimensional shingles because they give a multi-dimensional appearance, compared to the typical, flat look of standard 3-tab asphalt shingles. These premium asphalt shingles are more expensive, heavier, and more durable than the standard 3-tab shingles.
Selecting the proper asphalt roofing shingle for your climatic conditions will greatly extend the lifespan of your new roof. Asphalt roofs are prone to damage when exposed to drastic temperature changes over a short period of time. This condition is known as thermal shock. Proper attic ventilation is also crucial to ensuring the long service life of an asphalt roof.
Installation requirements for asphalt roofing are quite general:
Roof Deck: According to the NRCA asphalt shingles should be applied over closely spaced wood planks or continuous wood decking. For 16” rafter spacing’s plywood decking should be a minimum of 15/32 inch thick or ½ inch nominal exterior-grade. If oriented strand board (osb) is being used it should be a minimum 15/32 inch thick or ½ inch nominal exterior grade. For 24” rafter spacing’s 5/8 inch nominal thickness is recommended. The NRCA recommends exercising caution when roof decks are constructed of oriented strand board, preservative-treated wood and fire-retardant-treated wood. A qualified roofing contractor can provide information on appropriate roof decking materials for your roofing needs.
Underlayment: The underlayment provides temporary waterproofing during roof installation and acts as a permanent secondary waterproofing layer to the outermost roofing material. The NRCA recommendations for underlayment, commonly called “felt paper” specify a minimum of one layer of No. 15 asphalt-saturated felt applied horizontally in shingle fashion on roof decks having a slope of 18 degrees. A minimum of two layers of No. 15 asphalt-saturated felt paper is recommended for roof decks with a slope between 14 and 18 degrees. For extremely cold climates the NRCA recommends one additional underlayment layer known as an ice-dam protection membrane. Your roofing contractor can provide information about the necessity of this type of weatherproofing.
Fasteners: Roofing nails used to install asphalt shingle roofs should be 11-gauge or 12-gauge. They should be made of galvanized steel or an equally corrosion-resistant material. The nails used to install asphalt shingles should be long enough to fully penetrate all layers of roofing materials and reach into the underside of the roof deck. Nail heads should be smooth and flat with a low profile and shanks should be barbed for increased pull-out strength.
Flashing: When installing asphalt shingle roof systems flashings should be installed around the perimeter edge, at any penetrations, in open valleys, and along vertical surfaces.
The NRCA recommends the use of asphalt shingles that comply with American Society for Testing Materials (ASTM) standards- ASTM D 225 for organic shingles and ASTM D 3462 for glass fiber shingles. These standards govern the physical properties and components of asphalt shingle roofing materials. Consumers should note that not all asphalt shingles on the market comply with these standards. Carefully read shingle packaging and product literature to determine which asphalt shingles have met the standards laid out by the ASTM.
Asphalt roofing shingles come with warranties against manufacturing defects. These warranties, which generally last anywhere from 20-40 years, protect against thermal splitting, granule loss, curling, and cupping. The warranty will likely only cover the materials and will not protect against “Acts of God or Nature” which include hurricanes, hail storms, tornadoes, earthquakes, extremely high winds, etc. It is very important to fully understand the provided warranty as well as to have clear knowledge of situations, such as improper installation and insufficient attic ventilation, which may void the warranty. Your roofing contractor should provide you with detailed warranty information pertaining to the specific roofing material you select, as well as warranties offered by the contractor to cover roof installation.