Frequently Asked Questions

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

Click on the questions below to see the answers

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.

Steep-Slope FAQs

How are asphalt shingles made?

In the United States, asphalt shingles are categorized as either organic-based or fiberglass-based. Organic-based asphalt shingles are 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 is then saturated with a specially formulated asphalt coating and surfaced with weather resistant mineral granules. 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.

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.

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.

Low-Slope FAQs

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 BUR applied for maximum performance?

 

It's critical to get secure bonding of the roofing felts (plies) using bitumen. To achieve this bond the roofing contractor applies thin, uniform moppings of bitumen. This waterproofs the system and ensures proper adhesion for fusing the membrane system together. The temperature of the bitumen is critical. By heating it to the proper temperature the roofing contractor gets the right viscosity for proper mopping. The contractor heats the bitumen to its EVT or Equiviscous Temperature, the temperature at which it can be most effectively mopped into uniform layers. Each batch of bitumen should be labeled by the supplier with its EVT.

Once felts are rolled into place on the heated bitumen applicators pull brooms or squeegees over the felt or use some other method to make sure that its embedded in the bitumen.

The strength of the membrane depends on the type of felt used, the number of plies, overall ply construction, and the lapping of the overlaying felts. Typically, membrane ply construction is defined by headlap, endlap, and sidelap. Headlap is the distance of the overlap that exists between the lowermost and the uppermost plies of the shingled portion of the roof membrane when measured perpendicular to the long dimension of the membrane. Endlap is the overlap distance that is measured from where one roll of felt ends to where another begins. Sidelap is the overlap distance along the length of the felt where one roll of felt overlaps the adjacent overlying felt.

The application of Built-Up Roofing systems is detailed work, but the professional who pays particular attention to those details such as curbs, walls, flashings or other projections that interrupt the membrane, achieves a quality, efficient, long-lasting product for the building owner.

ARMA offers many sources of information to enable the roofing professional to do just that.

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 roof 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.

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.

ARMA FAQs

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

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.