mosaic rooftop representing asphaltic roofing

Asphalt Roofing Solutions

contractor wearing tan shoes laying an asphalt roof

What are asphalt roofing solutions and why are they trusted roofing solutions?

Asphalt is one of the oldest roofing technologies still in use today and it is a reliable solution for both residential and commercial roofing needs. Asphalt roofing uses asphalt as a waterproofing membrane.

Commercial asphalt roofing systems consist of two or more waterproofing layers. This redundancy provides building owners with durable waterproofing protection.

Asphaltic Roofing Installation Methods

Hot-Mopped

One of the oldest application methods still used today, involves melting blocks of asphalt in a large kettle and spreading the melted asphalt on the roof with mops.

a contractor applying a torched asphalt roofing system

Heat-Welded/Torch-Applied

Using a torch, the installer will melt the asphalt on the underside of the membrane. This will allow the sheet to adhere to the substrate below.

three contractors applying a cold-mopped roof

Cold-Applied

The installer will attach the roofing membrane by applying a liquid adhesive (i.e., Matrix 101) with a tool such as a notched squeegee or an applicator gun to the substrate or previously applied layer of roofing material.

Self-Adhered

This fast growing asphaltic installation method involves rolling out a membrane and peeling the film backing to adhere the membrane. This method can increase the speed of installation over the other three methods and does not produce unpleasant odors.

Asphaltic Roofing Systems

Multi-ply construction gives peace of mind that the roof is durable

illustration showing individual layers of built-up roofing

BUR (Built-Up Roofing)

BUR is the oldest of the current roofing technology and has been around for over a century. It consists of melting bricks of hot asphalt in a large metal kettle and using mops to apply that asphalt in-between a base sheet, ply sheets and lastly a cap sheet. Ply sheets and additional layers of asphalt can be added until the desired thickness has been reached. While cap sheets are very popular, they are not used on all jobs. Instead of using a cap sheet, some jobs are finished with a layer of gravel spread out over the last layer of asphalt.

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illustration showing individual layers of styrene butadiene styrene

SBS (Styrene Butadiene Styrene)

Introduced in the 1970’s, SBS features asphalt that has been modified (thus called modified bitumen) with the polymeric material SBS. This synthetic rubber allows the SBS sheets to achieve greater elongation ratings than other asphaltic systems. SBS systems also have the widest range of application methods as they can be hot-mopped, cold-applied, heat-welded or self-adhered. A typical SBS system consists of two plies of roofing membrane. First, a ply of smooth-surfaced SBS base sheet is installed, usually over insulation or cover board. The system is finished with a granulated cap sheet applied over the smooth base/ply sheet. SBS membranes are classified by ASTM numbers, types and grades:

ASTM D6162: SBS sheet using a combination of both polyester and glass fiber
ASTM D6163: SBS sheet using glass fiber reinforcement
ASTM D6164: SBS sheet using polyester reinforcement

ASTM D6162 and D6163 have three type classifications, Type I, Type II and Type III.
ASTM D6164 has two type classifications, Type 1 and Type 2. Typically, the higher the type, the larger the mass and physical properties.
There are two grades of SBS sheet:

Grade S: The sheet has a smooth surface
Grade G: The sheet has a granule surface

ASTM number, type and grade are specified by the architect in most cases.

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illustration showing individual layers of atactic polypropylene

APP (Atactic Polypropylene)

Introduced first in Italy in 1965 and subsequently brought to the United States one decade later in 1975, APP features asphalt that has been modified (thus called modified bitumen) to include atactic polypropylene – a plastic that allows the roofing membrane to achieve durability in addition to protection against the damaging effects of UV rays and weather events.. APP is typically only applied via a torch – a key difference from SBS. Just like SBS systems, most APP systems will consist of two membranes, a smooth sheet and a granule cap sheet. However, APP sheets are typically installed over either a BUR base sheet or thermal barriers as many substrates cannot be directly torched to. APP sheets are also used to recover existing roof systems. APP membranes are classified by ASTM numbers, types and grades.

ASTM D6222 – APP sheet using polyester reinforcement
ASTM D6223 – APP sheet using a combination of both polyester and glass fiber reinforcement

ASTM D6222 and D6223 have two type classifications, Type I and Type II. Typically Type II will have a larger mass and higher physical properties than Type I. There are two grades of APP sheet:

Grade S: the sheet has a smooth surface
Grade G: the sheet has a granule surface

ASTM number, type and grade are specified by the architect in most cases.

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EnergyCap™

Although not a separate type of roof technology like BUR, SBS or APP, energy cap roofing membranes are factory coated white cap sheets that reflect sunlight away from the roof and meet ENERGY STAR guidelines.There is an EnergyCap™ cap sheet available for each of the roofing technologies mentioned above.

Comparing Asphaltic Roofing Techniques

A great benefit of roofing with asphalt is the variety of technology and installation methods that are available.

¹ See the applicable manual for installation temperature instructions and ranges at https://www.gaf.com/document-library.

² GAF warranties and guarantees do not cover leaks or other damage due to wind speeds in excess of 55 miles per hour (unless additional wind coverage is purchased on eligible jobs). Refer to gaf.com for more information on warranty and guarantee coverage and restrictions.

³ GAF warranties and guarantees do not provide coverage against punctures (unless additional puncture resistance coverage is purchased on eligible jobs). Refer to gaf.com for more information on warranty and guarantee coverage and restrictions.

⁴Require the use of RUBEROID® "EnergyCap™" Products.

⁵See the applicable manual for installation at https://www.gaf.com/document-library. See applicable warranty or guarantee for complete coverage restrictions.

Where and When to Use

With three different types of asphalt roofs how do you decide which one to choose?

BUR

Roofs of essential buildings that need to stay open and operational at all times
BUR is a solution that has been used for over 100 years. The redundant applications allow for increased protection against damage and leaks.

APP

Roofs that need the reliability of a redundant asphaltic system without the odor and labor required for hot mopping.
APP is often used in smaller commercial roofing jobs, especially in urban areas. APP sheets are torched on to the surface below, therefore there is no need for a kettle, buckets or the inconvenience of getting asphalt onto the roof. In addition, APP systems typically consist of fewer plies than BUR jobs, allowing them to be installed faster and with a smaller labor force. Switching from a hot mopped application to a torch application will also reduce the odor around the work location allowing for more comfortable conditions for the workers and building occupants. A CERTA (Certified Roofing Torch Applicator) certification is required for a roofer to use a torch.

SBS

For roofs requiring the reliability of asphalt with more flexible application methods and labor availability.
Like APP, SBS can also be applied utilizing a torch (heat-welding). A CERTA (Certified Roofing Torch Applicator) certification is required for a roofer to use a torch. Many local ordinances also restrict the use of torches on roofs due to their risk as a potential fire hazard. Unlike APP, SBS can be applied in a variety of other ways including hot-mopped, cold-applied or self-adhered. Cold-applied applications are popular because they don’t produce as much odor as hot-mopped and do not require professional certifications like torching. Self-adhered is also a popular method because there is virtually no odor and it is typically faster to install.

EnergyCap™

For buildings that require ENERGY Star® certification or to be LEED® certified.
Utilize an EnergyCap™ sheet with any BUR, APP, and SBS system for projects that require the reliability of asphalt roofing and Energy Star® and LEED® certified solutions.

Tested in the field for decades, GAF asphaltic roofing materials provide durability and performance

Time-Tested

GAF has been selling asphaltic roofing products since 1892 when they created ready-to-lay asphalt roofing rolls which they called “RU-BER-OID roofing.” Ruberoid® as a brand is still around today and GAF’s Mod-bit (SBS and APP) line of products are still sold under this brand name.

Meets Third Party Standards

It is not enough that the products look great. They have to perform great too. This is why GAF thoroughly tests recommended roof assemblies both internally and externally at 3rd party labs such as UL and FM global. So whatever standards are required for a roofing job, GAF has a solution.

Reliable Manufacturer

GAF is a leading manufacturer of protective roofing systems and coatings for the construction industry. Our dedicated teams are positioned to provide guidance and support to the industry. GAF provides roof systems and coating solutions that meet the most rigorous industry standards.

Commitment to Quality

GAF asphalt roofing solutions are specifically formulated with durability in mind. Using only the high-quality raw materials, GAF's products are thoroughly tested to ensure performance.

When you need products, training & expertise from an industry leader

Talk to GAF first — from products designed for rooftop efficiency, to dedicated technical support that can assist with the specification process, to training designed to improve installer productivity, GAF provides solutions to support your business growth and profitability.

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