Taking Roofs To A Higher Level

June 14, 2005

nonwovens’ enhancements shape residential and commercial roofing markets

A roof should comprise high performance and durable materials to protect a building from nature’s harshest elements. From nonwoven roll goods manufacturers and roofing material distributors to roof installers and homeowners, demands for high quality roofing materials are becoming increasingly stringent. The role of nonwovens in the roofing market is varied, ranging from waterproofing and dimensional stability to acoustic and thermal insulation. Demands for the best in high-performance roofing materials also require nonwoven materials used in the roofing market to meet manufacturers’ strict standards.

“Nonwovens are supplied to the roofing industry as a reinforcement for bituminous membranes,” explained Richard Shaw, CEO of Freudenberg Texbond, Macon, GA, a division of Freudenberg’s Politex Group, headquartered in Novedrate, Italy. “Nonwovens are also directly sold to building contractors as geotextile materials and acoustic and thermal insulation. A roofing manufacturer guarantees/warranties its roofing products and will only buy nonwovens that meet strict technical properties and have a proven track record.”

Competition within the roofing market means that trends in new roofing materials are dictated by consumers. Additionally, roofing material demands are influenced by economic factors, climates, population growth and the availability of new materials.

What’s In That Roof?
Roofing material combinations and layers vary depending on what a manufacturer is looking to provide. Roofs for both commercial and residential markets consist of insulation material covered by a waterproofing membrane. Each of these layers contain different combinations of layers—some nonwoven and some not—that reinforce, insulate and offer support.

“Waterproofing membranes are generally made out of a reinforcing layer for support,” explained Andrea Visciglio, technical market development manager at Tessiture Pietro Radici S.p.a., Bergamo, Italy. “The reinforcing layer is composed of a nonwoven fabric in a polyester filament yarn or staple fiber, which is coated in a thermoplastic modified bitumen layer. Acoustic insulation comprises three layers: polypropylene spunbond material, a bitumen/polymer membrane or a PVC synthetic membrane and a polyester or polypropylene needlepunched layer.”

Asphalt shingles reinforced with a lightweight nonwoven fiberglass mat still dominate the residential roofing market, while commercial roofing tends to have a wider range of product combinations and layers. According to Maria Spinu, a marketing specialist at DuPont, Wilmington, DE, asphalt shingles make up 87% of North America’s residential roofing market. A nonwoven fiberglass mat is an asphalt roofing base material that is manufactured from glass fibers and offers a long lifespan and high strength. These benefits led Colbond Nonwovens, Arnhem, The Netherlands, to offer its standard bicomponent thermal bonded Colback nonwovens with glass reinforcements—Colback SDF.

“Glass reinforcements are glass scrims or mats,” explained Rob Noppen, director of marketing and sales for Colbond’s construction industry. “This composite of polyester nonwovens and glass scrims/mats gives an excellent process stability and allows the manufacturer to considerably increase production speed. Some of our customers told us that Colback SDF is an excellent nonwoven for architectural shingles due to tear resistance, nail holding strength, stability and good hail stone resistance.”

Nonwovens also stabilize or reinforce commercial asphalt roofing systems, which can have as many as eight of layers within the waterproofing membrane and insulation layers. “The commercial roofing market for asphalt roofing mainly uses Built-Up Roofing material (BUR), modified bitumen (MB) or single-ply material, which is typically ethylene propylene diene terpolymer rubber (EPDM), PVC and thermoplastics,” explained Ruben Garcia, director of new product development for Denver, CO-based Johns Manville’s roofing systems group. “Reinforcements include nonwoven polyester and fiberglass mats and laminates that are either made with scrims or nonwovens. BUR uses three or four layers of a thick reinforcement, such as an asphalt-covered wetlaid fiberglass mat, imbedded in hot asphalt, while modified bitumen uses two or three layers of spunbonded polyester.”

Modified bitumen, which is an asphalt modified with either Styrene-Butadiene-Styrene (SBS) or Atactic Polypropylene (APP) and a polyester nonwoven mat has become the preferred roofing system over BUR, in both North America and Europe. Manufacturers tout modified bitumen’s flexible installation methods, including hot asphalt, heat or torch welding or peel-and-stick adhesives. BUR has been known to lead to more errors and material inconsistencies during installation, because the asphalt is literally applied while roof installers are on top of the roof.

“In North America, the use of BUR is constantly decreasing,” said Freudenberg Texbond’s Mr. Shaw. “Modified bitumen products have a multitude of uses in commercial roofing, especially on the smaller jobs. These products have also become widely used in residential roofing as an underlayer.”

Freudenberg Texbond’s Macon, GA plant manufactures nonwoven polyester mats for roofing.
As demands for modified bitumen increase, manufacturers are developing ways to design polyester nonwoven mats to accommodate higher machine speeds. According to Mr. Shaw, polyester mat production usually involves using temperatures exceeding 200ºC while pulling the material over a caliber with a gap of about 2-5 mm. This induces stress on the material, causing the production speed to slow down. To address this issue, Freudenberg Politex has developed a line of polyester mats designed for higher speed production. Texbond’s mats comprise spunbonded polyester with fiberglass strands inserted in the machine direction during manufacturing. Currently, all of Texbond’s PET offerings use this patented process.

“With this process, modified bitumen producers have increased line speed yet still maintain puncture and tear resistance and dimensional stability,” Mr. Shaw explained. “These mats are often used as thin base sheets that are protected on the roof by reinforced polyester mats.”

Safety First
In addition to modified bitumen growth, single-ply roofing membranes are also showing promise to the roofing market. Single-ply roofing, also known as a cold adhesive or stick-and-peel adhesive, offers increased safety because it does not require torching or firing during installation. As roofers’ liability rates are especially high, up to 32% of a roofing company’s business, according to industry experts, safety has gained increasing importance to manufacturers.

“Safety and fire risks and the environment are some of the driving forces that will dictate market trends for years to come,” said Colbond’s Mr. Noppen. “We expect more pressure to reduce applications with open fires. The waterproof bitumen market not only focuses on process stability for fabrics that allow high production speeds. End product stability is also becoming important. With more dimensional stability, the roof’s materials are less likely to shrink and leak.”

Johns Manville supplies roofing materials for asphalt and non-asphalt roofing systems.

Fire resistance is not the only attribute of single-ply membranes. A single-ply sheet consists of thermoplastic polyolefins (TPO), which are blends of polypropylene plastic or polypropylene and ethylene propylene rubber (EPR) or EPDM, and are resistant to ultraviolet degradation while providing puncture resistance and tear strength. TPOs and PVC are commonly used in cool roofing systems because they have white membranes, which reflect light and reportedly allow roofs to be 50-60ºF cooler on hot days.

“Cool roofs are becoming increasingly popular because they have a high energy star rating,” explained JM’s Mr. Mahmood. “Both white roofs and polyester and glass nonwovens are replacing organic compounds worldwide, which are the equivalent of using a cardboard box to absorb water.”

Organic felts used in roofing applications typically consist of asphalt impregnated paper felt material.

The demand for these newer roofing materials is heavily affected by the varied worldwide economies as well as the availability of newer, high performance materials.

Residential Versus Commercial
The residential and commercial roofing markets vary significantly in different regions of the world. In North America, the residential market is ripe with activity, while the commercial side is stagnant. The growth in the residential roofing market, which is estimated by industry executives to comprise 70% of the North American roofing market, is attributed to new buildings and home improvements Lower interest rates give homeowners more initiative to invest in renovations or buy a home.

The North American commercial roofing market, on the other hand, is weak, as many companies do not want to invest money in roofing because of the poor economy. Manufacturers expect this situation to turn around in upcoming years.

“The commercial roofing market is in a slump because the overall business sector is somewhat depressed right now,” said Mr. Mahmood. “However, there are opportunities for the commercial roofing market. I can see the commercial roofing market growing and rebounding in two to three years. In addition to increases in the retail and construction sectors, the aging baby boomer generation means there will be a need to construct more healthcare and assisted living facilities.”

The current state of the commercial market is heavily impacted by the cost of installing a roof, which is far higher than installing a residential roof. According to Phil De Young, owner of commercial and residential roofing company Lakeland Roofing, Pompton Lakes, NJ, a commercial roof can cost as much as $32,000, whereas a residential roofing system for a $300,000 house will cost between $2000-$5000, just 1-3% of the home’s value. Manufacturers of commercial roofing materials are therefore more fastidious in choosing what materials they need, and business owners are not willing to make a new roof a top priority.

“A lot of businesses do not want to bother investing a large sum of money in a roof because of the poor economy,” Mr. De Young explained. “More companies are leasing buildings instead of buying them, which means they eventually move out and don’t need to worry about the condition of the roof.”
Freudenberg Texbond
produces spunbond-based roofing materials for bitumen style roofing.
While the North American commercial roofing market is lagging, the Asian roofing market is rapidly growing. Also converse to North America, the Asian residential roofing market is stagnant.

“Roofing market prices have been decreasing dramatically due to fierce competition among roofing suppliers in Japan,” explained Yukio Kawasaki, spunbond operations manager of Toyobo, Osaka, Japan, a supplier of needlepunched and resin bonded spunbond for the roofing market. “Commercial is growing at this point, while residential is slow because of a recession.”

To provide a clearer picture of how much construction is occurring, Johns Manville’s Mr. Mahmood said that in 2002, Beijing, China had more building construction than all of Western Europe combined, mainly because of the number of businesses moving to Asia to take advantage of its large population.

Like in Asia, the roofing market is developing in growing world regions, such as Eastern Europe, as newer roofing materials eventually become available here and the population increases. “We expect to see double-digit growth in these areas because of the increased construction of new buildings in accordance with population growth and user consciousness for newer materials,” said Serkan Gogus, commercial director of Mogul Nonwovens, Baspinar, Gaziantep, Turkey.

As for the future, manufacturers remain optimistic. “Nonwovens are ideal for roofing,” said Mr. Mahmood. “As the general standard of living around the world increases, people will have the money to invest more in nonwoven application-based roofs. Nonwovens will grow even further because they are longer lasting and provide the right medium for roofs. The overall North American roofing market is projected to remain strong, with a 2-3% growth every year.”

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