Frequently Asked Questions

Tips and information about ARMA, steep-slope and low-slope.

Do you have questions about commercial or residential asphalt roofing systems? If you can’t find answers here, please visit our Technical Bulletins or Ask an ARMA Expert.

Residential/Steep-Slope FAQs

How many homes are topped by asphalt shingles? Why?

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.

What are some of the benefits of asphalt shingles?

  • 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.”

How are asphalt shingles made?

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.

What are the different types of asphalt shingles?

  • 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.

How do I determine if a roof should be replaced?

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.

What is roll roofing?

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.

What are some steep-slope roofing terms?

Architectural Shingles: (See Laminated Shingles)
Asphalt: A bituminous waterproofing agent applied to roofing materials during manufacture.
Deck: The structural surface to which the roofing or waterproofing system (including insulation) is applied.
Flashing: Pieces of metal or roll roofing used to prevent seepage of water into a building around any intersection or projection in a roof, such as vent pipes, chimneys, adjoining walls, dormers and valleys.
Granules: Ceramic-coated colored crushed rock that is applied to the exposed surface of asphalt roofing products.
Hip: The inclined external angle formed by the intersection of two sloping roof planes. Runs from the ridge to the eaves.
Incline: The slope of a roof expressed either in percent or in the number of vertical units of rise per horizontal unit of run. Also referred to as slope.
Interlocking Shingles: Individual shingles that fasten together mechanically and provide greater wind resistance.
Laminated Shingles: These shingles have more than one layer of tabs to create extra thickness. They are often referred to as three-dimensional or architectural shingles because they create visual depth on a roof and impart a custom look.
Large Format Shingles: Generally rectangular or hexagonal in shape, these shingles do not have cutouts or tabs.
Membrane: A roof covering or waterproofing layer whose primary function is the exclusion of water.
Pitch: The degree of roof incline or slope expressed as the ratio of the rise, in feet, to the span, in feet.
Re-covering: The process of covering an existing roofing system with a new roofing system.
Re-roofing: The practice of removing an existing roofing system and replacing it with a new roofing system.
Ridge: The uppermost, horizontal external angle formed by the intersection of two sloping roof planes.
Roll Roofing: Asphalt roofing products manufactured in roll form, either smooth- or mineral-surfaced.
Saturated Felt: An asphalt-impregnated felt used as an underlayment between the deck and the roofing material.
Self-Adhered Eave and Flashing Membrane: A self-adhering water-proofing shingle underlayment designed to protect against water infiltration due to ice dams or wind driven rain.
Strip Shingles: Manufactured in both standard and metric dimensions, these asphalt shingles are approximately three times as long as they are wide, and are distinguished by the number of cutouts or tabs that they have. The most common are three tab.
Square: A unit of roof measure covering 100 square feet.
Thermal Insulation: A material applied to reduce the flow of heat.
Three-Dimensional Shingles: (See Laminated Shingles)
Underlayment: Asphalt saturated felt used beneath roofing to provide additional protection for the deck.
Valley: The internal angle formed by the intersection of two sloping roof planes.
Vapor Retarder: A material designed to impede the passage of water vapor into the roofing system.

Commercial/Low-Slope FAQs

What are some of the advantages of BUR?

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.

What is Modified Bitumen (MB) or Modified Bitumen Membranes (MBS)?

Modified bitumen membranes — MBS — 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.

What are Modified Bitumen modifiers? How do they work?

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.

What are reinforcing plies? What are they made of?

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.

How do I choose the roofing system that works best for a particular job?

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?

How is Modified Bitumen roofing applied for maximum performance?

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.

Why choose Modified Bitumen roofing systems?

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.

What are some low-slope roofing terms?

APP (Atactic Polypropylene): A modifier of asphalt (see modified bitumen roof membrane) that increases the UV resistance of the bitumen as well as its flexibility at low temperatures and improves its flow resistance at high temperatures.
Asphalt: A bituminous waterproofing agent applied to roofing materials during manufacture.
Built-Up Roof (BUR): A flat or low-sloped roof consisting of multiple layers of asphalt and ply sheets.
Base Sheet: A saturated or coated felt installed as the first ply in some multi-ply modified bitumen roofing assemblies.
Bitumen: (1) a class of amorphous, black or dark colored (solid, semi-solid or viscous) cementitious substances, natural or manufactured, composed principally of high molecular weight hydrocarbons and found in asphalts, tars, pitches and asphaltines; (2) a generic term used to denote any material composed principally of bitumen.
Bituminous: Containing or treated with bitumen.
Cap Sheet: A granule-surfaced coated sheet used as the top ply of a modified bitumen roof membrane.
Coated Sheet or Felt: (1) an asphalt felt that has been coated on both sides with harder, more viscous asphalt; (2) a glass fiber felt that has been simultaneously impregnated and coated with asphalt or coal tar on both sides.
Cold-Applied Roofing: A continuous roof membrane, consisting of plies of felts, mats or fabrics that are laminated on a roof with alternate layers of cold-applied roof adhesive and surfaced with a cold-applied coating.
Deck: The structural surface to which the roofing or waterproofing system (including insulation) is applied.
Felt: A flexible sheet manufactured by the interlocking of fibers through a combination of mechanical work, moisture, and heat. Felts are manufactured principally from vegetable fibers (organic felts), glass fibers (glass fiber felts), or polyester fibers (polyester felts); other fibers may be present in each type.
Fiberglass Mat: An asphalt roofing base material manufactured from glass fibers.
Flashing: Pieces of metal or roll roofing used to prevent seepage of water into a building around any intersection or projection in a roof, such as vent pipes, chimneys, adjoining walls, dormers and valleys.
Granules: Ceramic-coated colored crushed rock that is applied to the exposed surface of asphalt roofing products.
Incline: The slope of a roof expressed either in percent or in the number of vertical units of rise per horizontal unit of run. Also referred to as slope.
Low-Fuming Asphalt: An asphalt that contains a small amount of special
polymer that, when heated, floats to the surface, creating a skim layer on
the asphalt in the kettle that traps most of the fumes.
Membrane: A roof covering or waterproofing layer whose primary function is the exclusion of water.
Modified Bitumen Roof Membrane: A continuous, semi-flexible roof membrane assembly consisting of plies of saturated felts, coated felts, fabrics or mats between which alternate layers of bitumen are applied, either surfaced or unsurfaced.
Organic Felt: An asphalt roofing base material manufactured from cellulose fibers.
Re-covering: The process of covering an existing roofing system with a new roofing system.
Re-roofing: The practice of removing an existing roofing system and replacing it with a new roofing system.
Roll Roofing: Asphalt roofing products manufactured in roll form, either smooth- or mineral-surfaced.
Saturated Felt: An asphalt-impregnated felt used as an underlayment between the deck and the roofing material.
SBS (Styrene-Butadiene-Styrene): A modifier of asphalt (see modified bitumen roof membrane) that enhances the bitumen’s ability to resist the effects of aging the weather.
Self-Adhering Membrane: A membrane that can adhere to a substrate without the use of an additional adhesive. The undersurface of a self-adhering
membrane is protected by a release paper or film, which prevents the
membrane from bonding to itself during shipping and handling. These
membranes can be base sheets, ply sheets, cap sheets or underlayments.
Smooth-Surfaced Roof: A roof membrane surfaced with a layer of hot-mopped asphalt, cold-applied asphalt-clay emulsion, cold-applied asphalt cutbacks, elastomeric coating, or sometimes with an unmopped, inorganic felt.
Square: A unit of roof measure covering 100 square feet.
Thermal Insulation: A material applied to reduce the flow of heat.
Underlayment: Asphalt saturated felt used beneath roofing to provide additional protection for the deck.
Vapor Retarder: A material designed to impede the passage of water vapor into the roofing system.

ARMA FAQs

What is ARMA?

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.

What is ARMA’s mission?

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

Who are the Regular Members of ARMA?

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

Who are Associate Members of ARMA?

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

What are ARMA’s standing Committees and Task Forces? What do they do?

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.

How do I contact ARMA?

ARMA (Asphalt Roofing Manufacturers Association)
750 National Press Building
529 14th Street, NW
Washington, DC 20045
tel: (202) 591-2450; fax: (202) 591-2445
info@asphaltroofing.org

Frequently Asked Questions May 8, 2017

Contact ARMA

Asphalt Roofing Manufacturers Association
529 14th Street, NW
Washington, DC 20045
Tel: (202) 591-2450
Fax: (202) 591-2445

Social Media