SBS-Modified Bitumen Roofing

A look at product composition, properties and code-related attributes
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Sponsored by SOPREMA, Inc.
By Matt Davis and Ben Runyan

Recent Developments in SBS-Modified Bitumen

SBS-modified membranes have been around for a few decades, but more recent advancements have made them even more compelling as of late.

Reflectivity and Laminates

First of all, the introduction of highly reflective membranes has been somewhat of a game-changer. Since implementation of California’s Title 24 legislation in October 2005, there has been growth in white or “cool” roof initiatives across the U.S. Standards such as this stipulate levels of SRI or surface reflectance and thermal emittance for roofing material, pushing more people to adopt reflective roofing. Why? Because reflective roofs absorb less heat than a traditional roof, theoretically yielding reduced energy consumption related to building cooling costs, improved comfort in non-air conditioned spaces and reduced roofing system temperatures that cause material fatigue. Cool roofing can also benefit more than the building owner, diminishing urban heat island effects, lowering peak energy demands and creating ecological benefits when emissions related to energy production drop.

Cool roofing doesn’t limit you to synthetic single-ply membranes; SBS has options for whatever need you may have. As previously stated, SBS-modified membranes offer many options to achieve high-reflectivity, including granule and film options. The most desirable qualities of modified bitumen roofing systems can typically be retained in these constructions, and manufacturers strive to keep performance levels of cool roofing aligned with traditional alternatives. That said, there are some factors to consider if pursuing a cool roof construction, such as how much reflectance the surface will lose over time, what it will take to clean the membrane, potential consequences of that cleaning, condensation issues or ramifications of deflecting so much radiation.

Laminated products, specifically, account for one of the biggest advancements in SBS-modified roofing. Manufacturers offer products that utilize factory lamination of SBS-modified base sheets to various cover boards. This takes the process of applying the base layer out of the contractor’s hands and moves it into a controlled environment ensuring a fully-bonded base ply to the substrate. By doing this, contractors are able to save an estimated 35 percent or more on labor costs, getting the jobs completed much faster than previously possible, and with a higher quality of application.

Another new innovation in modified asphalt roofing is a granule surfacing that reduces airborne nitrogen oxides. These roofing granules are designed with a specialized photo-catalyst coating applied to the mineral that absorbs nitrogen oxide (NOx) gases in the atmosphere that are then cleaned and washed away by rainwater. A catalyst is a substance that makes a chemical reaction happen by reducing the energy needed to start the reaction. A photocatalyst is a catalyst where light provides the energy needed to make the catalyst work. A great example of this type of reaction is photosynthesis, one of the most crucial reactions for life on earth.

The gases in the atmosphere are emitted by many sources including cars, trucks, power plants and other industrial production processes and then released into the air. These gases react with Volatile Organic Compounds, or VOCs, in the atmosphere and sunlight to create what is commonly known as “smog” or ozone. This ground-level ozone or smog is unhealthy for humans, animals and plants. This process drastically reduces the amount of ground level pollutants, decreasing the greenhouse effect and creating healthier communities.

Additional Eco-Friendly Options

So, say you cannot have open flames, kettles, VOCs or strong odors where roofing needs to be applied. As previously discussed, options now exist that can be used over virtually any occupied space at any time. With the introduction of zero-VOC adhesives and cements, there is no need to wait for summer to work on school jobs, no need to close the office to reroof the building, and no need to disturb patients to complete a roofing project at a hospital. This new family of high-solids adhesives not only bonds the SBS sheet materials together, it also forms an additional layer of elastomeric waterproofing protection. Solvent-borne adhesives’ impact on the environment need not be a concern with this “greener” technology, and you gain strong performance in the meantime.

Safety is always a principal concern in roofing. When the use of a roofing torch or hot asphalt is a concern, or there are special circumstances that require near odorless application, specialized self-adhered membranes are the answer. These fully-adhered systems provide a multiply, redundant SBS-roofing system with all of the advantages of self-adhered application, including quick and easy application, no open flames or odor, and immediate bonding. All of these provide hassle-free, time and labor-saving application.

Unlike in the initial introduction, self-adhered membrane systems have come a long way. With options that do not require primer, film-surfaced sheets that drastically increase adhesion, and improve release films for both the backside and lap, self-adhered membranes are building a case for a strong future.

Speaking of “going green,” there is a push to do so in almost every industry now, and that includes roofing. There are now membranes that utilize a completely different chemistry—primarily thermoplastic polyurethane (TPU)—to fulfill these needs. More than one company produces these materials, and this technology has been in the marketplace now for several years. Today, these “green” materials can even be produced with canola oil, as a bitumen substitute, reducing fossil fuel usage by up to 75 percent. These membrane products are also much lighter than traditional SBS-modified membranes making installation easier for the contractor. Additionally, they are inherently UV-resistant, so there is no need to add granules or film to protect the membrane from UV rays. Finally, these membranes have been shown to outlive other forms of bituminous and synthetic roofing membrane products. Time will tell how the market accepts this new advancement.


Conclusions

The roofing industry has evolved significantly over the past 100 years, and as you have likely noted after reading through this article, that evolution has sometimes been counterintuitive. As market conditions, material availability and performance requirements have shifted, so has the type of roofing system constructions that we rely upon.

SBS-modified bitumen products have a long history of proven performance and quality, and today, with redundancy and durability, they provide some of the best waterproofing protection a building can receive. Especially given new developments in “cool” SBS-modified material performance and new adhesive chemistry, you can expect to see SBS-modified membranes positioned as compelling materials in the market for a long time.


Matt Davis, marketing manager for SOPREMA, and Ben Runyan, product manager for SOPREMA, are responsible for all aspects of the SBS product line including product development, differentiation, forecasting and positioning (brunyan@soprema.us).



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SOPREMA offers a comprehensive line of roofing, waterproofing, wall protection and civil engineering solutions combining superior products and systems with decades of proven performance. Our solutions include industry leading SBS-modified bitumen membranes, polymeric PMMA/PMA liquid applied membranes and synthetic single ply PVC membranes. www.soprema.us

 

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Originally published in Building Enclosure
Originally published in February 2017


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