Frequently Asked Questions

Asphalt shingles are the leading choice for residential roofing in the United States because they provide quality, durability, versatility and economy. Over 12.5 billion square feet of asphalt shingle products are manufactured annually – enough to cover more than 5 million homes every year. Four out of five homes are roofed with asphalt shingles.

Asphalt shingles offer consumers the broadest array of colors, shapes, and textures available. With an enormous range of styles, asphalt shingles can match almost every type of architectural design and achieve virtually any desired effect — and do it affordably.

• Product Performance. Asphalt shingles perform well in extreme temperatures and in areas where wind, water, and ice are prevalent.
• Affordability. The efficient, high-volume production and relatively low application cost of asphalt shingles provide consumers with an overall value that’s tough for other roofing materials to match, especially in terms of comparable life expectancy.
• Low Maintenance. Asphalt shingles, when properly chosen and applied, require little or no regular upkeep, and are easily repaired if damaged.
• Ease of Application. Asphalt shingles are considered to be the easiest of all standard roofing materials to apply. In addition, the flexibility and strength of asphalt shingles supports their application on a wide variety of roof designs.
• Fire and Wind Resistance. Asphalt shingles are manufactured to resist external fire and flammability standards, and carry Class A, B or C fire ratings, with Class A providing the greatest fire resistance. These fire ratings are defined by nationally recognized standards and tested by independent testing agencies. In addition, many asphalt shingles carrying a “wind resistance” label indicate that they have been manufactured and tested to demonstrate acceptable resistance in high-wind locations.”

In the United States, asphalt shingles are predominately fiberglass-based. Fiberglass-based asphalt shingles are manufactured with mat composed entirely of glass fibers of varying lengths and orientations. This fiberglass base is then surfaced with a specially-formulated asphalt coating, followed by weather-resistant mineral granules. Organic-based asphalt shingles were manufactured with a base (also termed mat or substrate) made of various cellulose fibers, such as recycled waste paper and wood fibers. This organic base was then saturated with a specially formulated asphalt coating and surfaced with weather resistant mineral granules.

• Strip Shingles — these asphalt shingles are approximately three times as long as they are wide. Manufactured in both standard and metric dimensions, strip shingles are distinguished by the number of cutouts or tabs that they have. The most common type of strip shingle is the “three-tab” shingle. Different textural and lighting/shadowing effects can be achieved with strip shingles depending on the number, shape and alignment of the cutouts.
• Laminated Shingles — these special shingles contain more than one layer of tabs to create extra thickness. They are also referred to as three-dimensional or architectural shingles because they create visual depth on a roof and impart a custom look. Laminated shingles continue to be a favorite among builders, roofing contractors and homebuyers.
• Interlocking Shingles — as the name suggests, interlocking asphalt shingles are individual shingles that mechanically fasten to each other, and are used to provide greater wind resistance. They come in various shapes and sizes providing a wide range of design possibilities.
• Large Format Shingles — generally rectangular or hexagonal in shape, these shingles do not utilize cutouts or tabs.

Sooner or later, every roof needs to be replaced, usually due to the long-term effects of weathering. If a residential roof is more than 20 years old, it is a prime candidate for reroofing. To determine if you need a new roof:

• On the ground, walk around your home with binoculars and inspect your roof for cracked, curled or missing shingles, as well as any excessive loss of the protective mineral granules. DO NOT CLIMB ON THE ROOF; walking on the roof is dangerous and can damage your roof.
• In your attic, take a flashlight and look at the underside of the roof deck and rafters for any stains or wet spots indicating water leaks.

Asphalt shingles can often be applied directly over existing roofs without the necessity of tearing off the old roof. However, new shingles can not be properly applied over hard or brittle materials, uneven surfaces for nailing or roof decks with warped, rotted or unsound support that should first be replaced or repaired.

Some local ordinances forbid reroofing over two or more layers of shingles. If a home already has been shingled several times, it is important to first determine if the roof deck can support another layer of shingles before undertaking any re-roofing project.

In addition to asphalt shingles, asphalt roll products are used for residential roofing applications (primarily for underlayments and flashings). There are four basic types of roll roofing materials, each tailored for use in certain job requirements:

• Smooth Surfaced Roll Roofing: Also termed coated felt, this smooth-surfaced roll roofing is covered with ground talc or mica. It is used primarily as flashing to seal the roof at intersections and protrusions, and for providing extra deck protection at the roof’s eaves and valleys.
• Saturated Felt: This asphalt-impregnated, organic-based felt is used as an underlayment between the roof deck and the roofing material. Saturated felt is produced in a variety of weights.
• Specialty-Eaves Flashings: This self-adhering, polymer-modified bituminous sheet material is designed for special flashing applications along roof eaves and in other areas. It is used particularly in regions where ice dams and water backups are common.
• Mineral-Surfaced Roll Roofing: This type of roll roofing is used alone as a primary roof covering, most frequently on small or secondary-use buildings such as supply buildings, barns, garden sheds, etc. The top surface of the roll is imbedded with mineral granules.

1 – Ventilation moves heat out of the attic space. This helps prolong the service life of the roof. This can also improve the energy efficiency of the house by reducing the burden on cooling systems such as air conditioners. Attic ventilation can also help fight ice dams in cold climates.

2 – Ventilation moves occupancy-generated water vapor (cooking, cleaning, laundry, breathing, etc.) out of the attic space. This helps avoid several problems associated with excessive moisture in the attic (mold, wood rot, wet attic insulation, etc.).

For information in more detail, see the ARMA Technical Bulletin “Why Ventilation is Important.”

Attic ventilation is the free flow of outside air through the space immediately beneath the deck of an asphalt shingle roof. This ventilation requires a combination of incoming air at the bottom of the attic roof deck (either in the overhang/soffit or on the bottom edge of the roof) and air exhaust at or near the highest area of the roof deck (typically at the ridge). Care should be taken to avoid obstructing the flow of air from intake to exhaust. Proper attic ventilation provides airflow in all areas of the vented attic space.

While attic ventilation is a simple principle, making it happen can be complicated. For more information and details, see the following ARMA Technical Bulletins:

• “Considerations in Attic Ventilation System Selection”
• “Application of Asphalt Shingles to Decks Installed over Insulation or Radiant Barriers”
• “Why Ventilation is Important”

Built-up roofing systems have had a long-standing popularity, due in large part to the success and proven reliability of BUR. The stock of 20, 30 and 40-year-old BUR roofs still in excellent condition attests to this fact. Specifically, BUR roofs offer:

• Multi-Layer Protection – the multiple layers of bitumen and bitumen saturated “felts” make a water-resistant barrier capable of providing many years of reliable protection from the elements.
• Thermal Performance – Built-up roofing systems exhibit exceptional resistance to the conduction of heat between the exterior and interior of a building, resulting in noticeable reductions in heating and cooling costs.
• Fire and Uplift Resistance — Built-up roofing systems are tested through Factory Mutual Research Corporation to meet very strict fire resistance requirements and ensure adequate uplift resistance under extreme wind conditions.
• Economy — Compared to other high performance commercial roofing systems, built-up roofing is one of the best investments on the market due to its competitive cost per year of expected service life.

Modified bitumen membranes combine the features of a built-up roof with the added tensile strength from its polymer modification. Using a reinforced sheet that is prefabricated in the plant, modified bitumen systems require a less labor-intensive application and can be applied cross-platform in both commercial and certain residential applications.

A modified bitumen roofing system is composed primarily of polymer-modified bitumen reinforced with one or more plies of fabric such as polyester, fiberglass or a combination of both. Factory surfacing, if applied, includes mineral granules, slag, aluminum or copper. The bitumen determines the membrane’s physical characteristics and provides primary waterproofing protection, while the reinforcement adds strength, puncture resistance and overall system integrity.

Factory-assembled, modified bitumen membranes undergo strict quality control standards to ensure uniform thickness and consistent physical properties throughout the membrane. The finished roofing system is usually a two- to four-ply system consisting of a modified bitumen membrane and a base sheet, with additional plies for added strength if needed. The substrate often determines which ply system is best specified.

The finished roofing membrane may consist of one or more modified bitumen sheets, or it may be comprised of a combination of built-up roofing (BUR) felts and one or more modified bitumen sheets. The type of substrate and the performance objectives influence the specification of the modified bitumen membrane system.

There are modified bitumen membranes tailored to almost every type of construction design and climate: for new roofing or reroofing of commercial buildings, residential high rises, domes, spires, and most categories of low-slope or steep-roof roofing. Thus there are a variety of modifiers, and types of reinforcements and surfacings available.

Modified bitumens generally use a traditional waterproofing medium — asphalt — modified with atactic polypropylene (APP), styrene butadiene styrene (SBS), synthetic rubber or other agents that create a uniform matrix that enhances the physical properties of the asphalt. SBS and APP are the most common bitumen modifiers.

• SBS (Styrene-Butadiene-Styrene) modifies the asphalt by forming a polymer network within the bitumen. SBS gives the bitumen rubber-like characteristics and improved resistance to aging and weathering. Most SBS-modified bitumen sheets are either set in hot mopping asphalt, torch-applied or adhered with cold-process adhesives. SBS-modified bitumen sheets that do not have factory applied granule or foil surfacing need some form of field-applied ultraviolet protective coating.
• APP (Atactic Polypropylene) is a thermoplastic polymer which forms a uniform matrix within the asphalt. This enhances the bitumen’s performance by increasing its UV resistance, increasing its flexibility at low temperatures and improving its flow resistance at high temperatures. APP-modified bitumen sheets are generally applied using a propane-fueled torch. Applicators use the heat to soften the modified bitumen on the underside of the sheet. The sheet’s bottom surface becomes a molten adhesive which flows upon the substrate and then cools to form a waterproof adhesive bond. Some APP sheets can also be applied with cold process adhesives.

While modified asphalt provides the primary waterproofing characteristics of these membranes a reinforcing ply adds strength and puncture resistance. Glass fiber and polyester plies are the most commonly used reinforcing fabrics. Each has distinctive properties. Polyester has excellent elongation, tensile strength and recovery. It provides good puncture resistance and stands up well to foot traffic. Glass fiber resists flame penetration and provides excellent tensile strength and dimensional stability.

The combination of asphalt, modifiers and reinforcements determines the characteristics of a specific modified bitumen membrane. To obtain the best roofing system possible, the designer, building owner and contractor should understand the dynamics of the roof as well as the roofing system when specifying either APP or SBS modified roofs.

The architect, specifier, building owner and roofing contractor should examine the following parameters when choosing a roofing system:

• What is the building’s type and usage?
• What building code requirements apply to the system?
• What is the estimated service life of the roof system? What type of maintenance will be required to maximize the service life of the roof system?
• What kind of roof deck will be used (type, size, slope)?
• How much is the roof deck expected to move relative to the roof perimeter? Shrinkage of the deck material? Moisture content of the deck?
• Access for equipment on the roof?

The application of modified bituminous roofing is a construction process that involves the skillful arrangement of several components as specified for the process. Roof performance is determined by factors that include building design, job specifications, materials quality and suitability, application procedures and maintenance. The level of quality in the workmanship during the application process is critical.

The application of modified bitumen roofing systems is not an exact science. It’s a craft that involves people, roofing professionals, who deal with a broad range of materials, designs, customs, techniques, weather events, and climates. ARMA recognizes the importance of these critical factors as they affect the quality of modified bitumen roofing. These factors are controlled by applicable inspection and review procedures carried out during the development, manufacturing, production, and application stages.

Since gaining acceptance in the roofing industry during the 1970s, the use of modified bitumen membrane roofing systems has increased steadily. Today modified bitumen membranes are the fastest growing roofing materials in the industry.

Considered a quality “hybrid” system, MBS provides the features of a built-up roof with the added tensile strength and elongation of a modified bitumen cap sheet, as well as the quality assurance of in-plant  membrane fabrication uniformity and control, and reduced labor requirements for installation.

In addition, MBS products undergo the same fire and uplift resistance testing standards as BUR, providing the commercial customer full assurance of appropriate fire and uplift resistance.

The Asphalt Roofing Manufacturers Association (ARMA) is the North American trade association that represents the majority of the asphalt roofing industry’s manufacturing companies and their raw material suppliers. Together these companies produce a variety of bituminous-based residential and commercial roofing systems, including asphalt shingles, roll roofing, built-up roofing systems and modified bitumen-roofing systems.

ARMA is committed to serving the asphalt-roofing industry and its consumers. Its mission is:

• To facilitate the dissemination of the latest general and technical information on roofing materials, practices and issues
• To facilitate and sponsor research to encourage the improvement of product performance
• To serve as the industry’s voice in contributing technical data and information to building and code officials, regulatory agencies and allied trade groups
• To promote and further the sale and use of bituminous-based roofing products
• To defend and protect the asphalt roofing industry from actions that may restrict the sale of certain bituminous-based roofing products
• To provide a forum to coordinate activities that would benefit from group attention
• To provide liaison with others having an influence on the industry (i.e., other associations, building code agencies, etc.)
• To present collective positions on issues of concern
• To maintain a strong and active membership

ARMA Regular Members are manufacturers of asphalt shingles, built-up roofing materials, modified bitumen roofing systems, or allied products.

ARMA Associate Members are suppliers of major components, equipment or services used in the manufacture or installation of asphalt roofing products.

ARMA operates through a structure of strong committees with participation by a broad representation of Regular and Associate Members:

• Built-up Roofing/Modified Bitumen Committee 
  Assist ARMA staff in the compilation and dissemination of pertinent information through the use of technical bulletins, manuals/guides, trade press and internal/external newsletters to maintain and enhance the sale of, and to promote the proper use of bituminous-based residential, built-up, and modified bitumen roofing products. Maintain liaison with related trade groups, the government, code bodies, consumer groups and the public in order to develop greater mutual understanding and relations as well as programs to promote bituminous-based residential, built-up, and modified bitumen roofing products. Foster the development and planning of research and testing programs to improve product and roofing system performance. Investigate product performance efforts of other manufacturing associations to assist in determining the best approach to performance evaluation for ARMA. Monitor and analyze the ARMA Shipment Report (Category C – modified bitumen) for potential revisions and improvements and to determine the methods in which the report can be better utilized for the benefit of the ARMA membership.
• Residential Roofing/Research Committee 
  Assist ARMA staff in the compilation and dissemination of pertinent information through the use of technical bulletins, manuals/guides, trade press and internal/external newsletters to maintain and enhance the sale of, and to promote the proper use of bituminous-based residential, built-up, and modified bitumen roofing products. Maintain liaison with related trade groups, the government, code bodies consumer groups and the public in order to develop greater mutual understanding and relations as well as programs to promote bituminous-based residential roofing products. Identify potential residential research needs for the industry and Conduct Board approved product system performance research and investigate approaches to promulgate consensus standards. Establish liaison with other testing and standards developing organizations i.e., Underwriters Laboratories, ASTM, Factory Mutual.Monitor and analyze the ARMA Shipment Report (Category A – shingles) for potential revisions and improvements and to determine the methods in which the report can be better utilized for the benefit of the ARMA membership.
• Industry Affairs Committee 
  Monitor and report on issues relating to the manufacture of asphalt roofing products. Compile and disseminate in-plant safety and health information; provide information and alert bulletins related to safety and health regulatory issues; investigate other manufacturing association safety and health programs. Assign and share company non-proprietary process TQM programs through presentations, annual surveys and experiences from other manufacturing associations. Provide information to members and others regarding ARMA’s involvement in recycling and waste minimization efforts. Recommend to the Board of Directors annual issue priorities and an Association action plan. Prepare analysis of other Association’s monitoring and staffing efforts regarding regulatory surveillance. Develop financial proposals for issues management.
• Communications Committee 
  Define and establish the mechanism with which to articulate the technical and economic advantages of asphalt based roofing. Design trade and consumer promotional/educational programs to assist users in assessing the value of asphalt-based roofing. Oversee the procedures/controls for the Quarterly Shipment Report. Compile and analyze product market information to compare with asphalt-based roofing data. Assist ARMA staff in creating positive information on product and system performance. Prepare and distribute public affairs information on issues impacting on ARMA members, product suppliers and users.
• Codes Task Force 
  Monitor various code organizations, including ICBO, BOCA, SBCCI, CABO, as well as international groups for code development activities. Identify codes priorities of interest and relevance to ARMA member companies, and the bituminous roofing industry. Liaison with other groups having related interests. To negotiate, recommend and propose specific codes actions.

ARMA (Asphalt Roofing Manufacturers Association)
2331 Rock Spring Road
Forest Hill, MD 21050
tel: (443) 640-1075; fax: (443) 640-1031
info@asphaltroofing.org