Polymer modified bitumen membranes have been utilized with great success all over the world for decades, and there’s no reason to think things will change anytime soon, according to David Allen of BITEC Inc. “They have a good track record,” said Allen, vice president of operations and technical services for BITEC, which is headquartered in Morrilton, Ark. He asserted that modified bitumen manufacturers and their membranes would survive the ups and downs of the roofing market this year and beyond.

BITEC used self-adhered MAT-40 tile underlayment and Imperflex MSA on the Roosevelt Building at Pima College in Tucson, Ariz.


The Susquehanna Valley Mall in Selinsgrove, Pa., features 179,400-square-feet of Firestone SBS FR, which was chosen because of the product's durability and elongation properties. (Photo courtesy of Firestone Building Products)

Polymer modified bitumen membranes have been utilized with great success all over the world for decades, and there’s no reason to think things will change anytime soon, according to David Allen of BITEC Inc. “They have a good track record,” said Allen, vice president of operations and technical services for BITEC, which is headquartered in Morrilton, Ark. He asserted that modified bitumen manufacturers and their membranes would survive the ups and downs of the roofing market this year and beyond.

“Correctly made, high-performing polymer modified bitumen remain very attractive to quality-conscious roofing contractors,” Allen said. “Many who own small contracting businesses and rely on quality, plus a high level of manufacturer customer service, will survive.”

“This is not to say these contractors use only polymer modified bitumen membranes; they use other membrane models as well,” Allen continued. “Yet, they do recognize and accept them as an integral part of their waterproofing repertoire. No one roofing product cures all ills.”

Founded in 1986, BITEC, which is short for Bitumen Technology, is a specialty manufacturer of APP and SBS roofing and waterproofing membranes. The company continues to engineer and design new products that ensure the company’s position of providing high-quality products that meet or exceed the needs of customers, contractors, architects and property owners. BITEC markets products through distribution within the United States and Canada. The products are not only roofing membranes but also an integral part of an asset protection system.

”We’re a small fish in a pond,” Allen said. “But we are all about quality service - the unsung heroes. We deal with the smaller independent man who takes pride in their work. The bulk of our business is with individuals that are quality conscious.”

Allen believes production of asphalt fluxes should continue for some time. “Even though new refining techniques are supposed to reduce availability of high-quality asphalt for polymer modification, asphalt fluxes will remain available for this as well as other purposes,” he said.

Allen said polymer producers are also more efficient in the manufacture of their products. “The polymer offering is less byproduct and/or ‘off-spec’ polymers,” he said. “Many polymer modified bitumen membrane producers are now forced to use the better grade polymer. This improves the membrane’s performance.” Regardless of open flame restrictions, the thermofusable (torch grade) membrane is not extinct, Allen said.

“As a manufacturer, we continue producing high volumes of APP membranes, which are marketed throughout the U.S.,” he said. “This trend will continue. I do believe we are not alone in this respect.” Self-adhered, hot asphalt and cold adhesive applied membranes offer contractors alternatives, said Allen, who noted demand for SBS modified bitumen membrane is increasing, and that polymer modified bitumen membranes will accept a wide range of roof coatings.

“Until some of the above-mentioned factors substantially change, the polymer modified bitumen membrane will remain a vital part of the roofing industry,” Allen said. “Adding to this success are those manufacturers who provide their services on a personal and professional level, who believe in their customer, which in every case is the roofing contractor.”

Firestone SBS Premium FR over Firestone composite polyiso insulation was selected for the reroof of the 850,000-square-foot Miami Beach Convention Center and Jackie Gleason Theater of the Performing Arts in Miami Beach. (Photo courtesy of Firestone Building Products)

Mod Bit Trends and Colors

Ruben Garcia, asphalt manager for Firestone Building Products, said there are areas in commercial modified bitumen systems that are declining in popularity and others that are showing growth. “The market has seen APP membrane usage decline, while SBS systems are holding their own,” Garcia said. “The need for systems that do not require the use of hot mopping of asphalt or torch applications has spawned the need for alternative installation methods of attachment. This trend has resulted in the use of cold-applied and self-adhered modified roofing systems and products.”

Garcia said the most commonly used colors in mod bit products are white and black, but he noted that other colors include more earth tones - buff and brown. “The need for a white reflective roofing system in different parts of the country has also seen new cap sheets with reflective coatings or granule systems added to the membrane in the factory to meet these new reflective needs of the industry.”

Garcia noted that mod bits products are basically the same in terms of how they are made compared to 10 years ago. “What is different in these well-established products is how they are installed (cold adhesives and self-adhered) or their surfacing to meet the reflective needs of the market,” Garcia said. “Firestone continually monitors our customers from the contractor to building owner. As we collect their input, we will add new products to meet their needs.”

A Ruberoid® Energy Cap™ 30 FR is one of the latest installations in commercial modified bitumen systems. (Photo courtesy of GAF Materials Corp.)

The Current Market

Joe Hobson, director of communication for Asphalt Roofing Manufacturers Association (ARMA), said the roofing industry is “experiencing a growing continuation of and continued use of” modified bitumen systems in the commercial roofing segment.

“Indications show there is a good strong market,” Hobson said. “There are enhancements, continually making advancements in its own protocol. Mod bit systems remain popular, and are increasing commercially.” Hobson said it appears a strong segment of the roofing industry is staying on the modified bitumen trail. “It seems like a very good year,” he said referring to 2008. “Put mod bits up against other products, and it seems modified bitumen are doing good.”

Hobson said through the years people have acquired a growing acceptance of modified bitumen systems. “It’s proven reliable, dependable - a proven product,” he said.

Here is a completed project by BITEC at Pima College in Tucson, Ariz. The project featured BITEC’s self-adhered MAT-40 tile underlayment and Imperflex MSA.

Benefits of Mod Bit Systems

Since the 1980s, commercial modified bitumen systems have been one of the workhorses of the roofing industry based on the following factors, according to ARMA officials:
  • Long Life. For low-slope commercial roofing, asphalt roofing makes a strong case for sustainability due to the long life cycles. A high quality asphalt modified bitumen or built-up roof (BUR) that is well designed, properly installed and well maintained could last for decades. The features that made the asphalt the leading quality commercial roofing system in the past are still important today. These features include ply redundancy, moisture protection, versatility, low cost, high strength, adaptability to the job, and, most important, its endurance.
  • Innovation. The asphalt roofing industry is a vibrant, highly competitive industry, which has developed many innovative products over the past century. Most noteworthy are the modified bitumen membranes. However, none of these new products has made hot-applied asphalt obsolete. Many quality asphalt systems today combine the use of modified bitumen sheets with hot applied asphalt BUR in a hybrid system. These systems can be tailored to the application, giving roof consultants and building owners more design choices for longer-lasting roofs. Modified bitumen base or cap sheets can improve the performance of an asphalt BUR system in several respects, but they do not supplant the basic idea of “building up” a roof with the application of hot asphalt in multiple layers.
  • Reflectivity. The state of California passed major legislation relating to energy conservation in commercial buildings. Title 24 has been a topic of great interest to contractors, consultants, building managers, and architects. There are many advantages that can be garnered from modified bitumen chemistry, but perhaps none is more timely and appropriate than the recent introduction of highly reflective cap sheets. These cap sheets serve as an outstanding example of the supporting role of modified bitumen in enhancing the properties and performance of BURs. While the term “reflective BUR” may seem like a contradiction in terms, even the stringent reflectivity requirements of Title 24 do not preclude the use of a hybrid BUR system.
  • Cool Roofing. Cool roofing encompasses maintenance, “cleanability,” and the effect of reflectance on life cycles. Interestingly, systems last even longer when surface temperatures are reduced in hot weather. So the use of a reflective mod bit cap sheet or light-colored gravel can prolong the already long life expectancy of an asphalt system.