Frequently Asked Questions about PVC Roofing Systems: Part 2

Q: How are PVC roofing systems sustainable?

A: More than 26 Life Cycle Assessments (LCAs) confirm that PVC roofing membranes are an outstanding sustainable choice for many reasons:

  1. Energy efficiency.
  2. Mitigation of urban heat islands that cause elevated levels of air pollution.
  3. Waste reduction throughout their life cycle: production, shipment, installation, post-consumer disposal.
  • Only 43 percent of PVC membrane composition is derived from nonrenewable fossil fuel feedstocks, compared with other single-ply and built-up systems that contain a much higher percentage.
  • PCV requires less energy to produce than competitive products.
  • They typically last for 20 to 30 years, reducing the rate of waste flow into landfills.
  • There is virtually no scrap in PVC roof manufacturing or installation.
  • PVC roofs can often be installed directly over old roofs.
  • Many PVC roof manufacturers have post-use recycling programs.
  • PVC roofing membranes are inherently recyclable, and are the only roofing material that can be recycled back into roofing products.
  1. Extremely low contribution to greenhouse gases and hazardous emissions, due to closed-loop manufacturing.
  2. There are at least 10 categories in which white PVC roofing systems can help earn points under the LEED® rating systems.

Q: Why do PVC roofing systems last so long?

A: Among the reasons that PVC roofing systems typically last between 20 and 30 years with very little maintenance are the following:

  1. Reflective properties extend the useful life of the roof substrate materials by reducing the rate of deterioration by as much as 75 percent.
  2. Waterproof characteristics that prevent PVC from rotting, rusting or corroding.
  3. Custom prefabricated systems from some manufacturers that help ensure optimal installation and long-term performance.
  4. Heat-welding properties that create seams that are stronger than the membrane itself while eliminating the need for chemicals, torches or other hazardous installation methods.
  5. Inherent flame resistance strengthened by the addition of flame retardant additives, which facilitates Underwriters Laboratories Class A ratings and Factory Mutual Class 1 ratings.
  6. High resistance to chemicals, grease, and other harmful substances that is common on rooftops.
  7. Simple repair procedures normally accomplished by heat-welded patches or seams.

Setting The Bar For Sustainability

Numerous terms and ideas are used to describe products, processes and techniques that are said to be sustainable or provide high performance. Terms such as “green,” “environmentally-friendly,” “recyclable” and “long life-cycle” attempt to define the concept of sustainability. But what really is sustainability? How do you determine whether a product is truly sustainable or not?

Along with the growth of green design programs such as LEED® and Green Globes, there have been efforts by state and local governments to add sustainability guidelines to building codes. The federal government has indicated it plans to add green design guidelines to its building requirements as well.

Guidelines for many performance criteria are established based on standards. There are ANSI standards for PVC sheet roofing, for measuring emittance and for calculating a solar reflectance index. There are LEED standards that attempt to set the bar for high performance building design and construction. There are standards for wind loads and for material strength and thickness. Sustainability standards already exist for a few building products, but not for single-ply roofing. Without specific, complete standards for single-ply roofing, PVC-based products could become part of a broad category that would not accurately or effectively present the complete green picture for vinyl roofing.

The Vinyl Roofing Division of the Chemical Fabrics and Film Association has undertaken an ambitious effort to develop and obtain approval for an ASTM standard for Sustainable Thermoplastic and Thermoset Single-Ply Membrane Roofing. The process is anticipated to take another 6 – 12 months, but in the end the standard will provide solid guidelines as to what constitutes a sustainable single-ply roofing system. Stay tuned for updates as the project progresses.

Frequently Asked Questions about PVC Roofing Systems: Part 1

In this seven-part series, we will address common questions about polyvinyl chloride – PVC.

Q: How long have PVC, or vinyl, roofs been around? Are they among the leading systems for commercial roofing?

A: Originally introduced in Europe in the early 1960s, PVC roofing systems were among the first single-ply commercial roofing materials. Today, reinforced PVC roofs – also called vinyl roofs – account for 65 percent of the European commercial roofing single-ply market, and North American growth has outpaced the commercial roofing industry as a whole for more than 10 years. In 1985, PVC roofing systems were the first single-ply roofing products to obtain a standard designation from the American Society for Testing and Materials (now ASTM International): ASTM D4434 – Standard Specification for Poly (vinyl chloride) Sheet Roofing – which is regularly updated. Today, PVC is an increasingly popular thermoplastic roofing membrane worldwide.

Q: What makes PVC roofs so special?

A: PVC roofing systems have witnessed tremendous growth in recent years due to a variety of standout characteristics, notably: longevity; durability in harsh weather and temperature extremes: low life-cycle costs; energy efficiency; heat and solar reflectance; flame resistance; chemical and grease resistance; ease of maintenance; ease of flexibility of installation; and inherent recyclability/re-use, among many other benefits. Often referred to as the first “cool roofing” system, PVC is energy-efficient, environmentally sustainable, long-lasting and cost-effective.

Q: How are PVC roofs energy-efficient?

A: Lots of ways! White PVC roofing systems not only reflect sunlight and solar energy to save building owners up to 40 percent in annual electricity costs, they also improve the performance of the underlying roof insulation by 25 to 50 percent; extend the useful life of the roof by as much as 75 percent; enable rooftop cooling equipment to run more efficiently; contribute to better indoor air quality and comfort; and collectively help mitigate the effects of urban heat islands and the air pollution they cause.

A comprehensive environmental profile of vinyl roofing systems can be downloaded from the website of the Chemical Fabrics and Film Association.

Is Roofing Part of Your Energy Management Strategy? Part 5

Regulatory Mandates

The obvious benefits of cool roofing systems have resulted in many federal, state, and local government initiatives designed to encourage or mandate their use.

Below is brief overview of Federal Energy Management Policy and Mandates. The full overview can be found here.

National Energy Conservation Policy Act (NECPA)

Signed into law in 1978, NECPA serves as the underlying authority for Federal energy management goals and requirements. It is regularly updated and amended by subsequent laws and regulations and is the foundation of most current energy requirements.

Section 543 of NECPA required a reduction in Btu/GSF of 20 percent by 2000, life-cycle cost methods and procedures, budget treatment for energy conservation measures, incentives for Federal facility energy managers, reporting requirements, new technology demonstrations, and agency surveys of energy-saving potential.

Section 102 of EPAct 2005 re-established energy reduction requirement for Federal buildings. The requirement uses a base year of fiscal year (FY) 2003 and requires reductions of 2 percent per year in energy use per square foot, leading to a 20 percent reduction in FY 2015.

In 2007, President George Bush signed Executive Order 13423, strengthening Federal environmental, energy, and transportation management. Section 2 of the Order set more challenging goals than EPAct 2005, requiring a 3 percent reduction in energy intensity per year and leading to a 30 percent reduction in 2015 compared to the base FY of 2003.

Also in 2007, President Bush signed the Energy Security and Independence Act of 2007 (EISA). EISA adopts the energy intensity reduction goals of Executive Order 13423 beginning in FY 2008 with a 9 percent reduction and increasing to a 30 percent reduction in FY 2015.

Click the links below for more detailed information.

Energy Policy Act of 1992

Executive Order 13221

Energy Policy Act of 2005

Executive Order 13423

Energy Independence & Security Act of 2007

Cool Roofing is a Win-Win Energy Management Strategy

Most building owners don’t need regulation to recognize a good thing when they see it. Even without regulatory mandates, PVC and TPO cool roofing systems have been the fastest growing commercial systems in America since the late 1990s. Many utility companies now offer rebates for using reflective roofing systems. These rebates – which can amount to several thousand dollars on large roof installations – are offered nationwide, not just in southern climates.

Best of all, cool roofing is a rare example where there are really no cost or performance tradeoffs for selecting an energy-efficient, environmentally-friendly system. The best single-ply cool roofing systems protect buildings from the rain, sleet, and snow just as well, or better, than alternative dark-surface roofing systems, and they can also play an important part in the energy management strategies of smart building owners and managers.

Positive Responses to Negative Statements About PVC: Part 6

Statement: “PVC is the largest source of dioxin, the most poisonous chemical on earth.”

The facts: There will always be dioxin present in the environment because the most common sources of dioxin are natural contributors such as forest fires and volcanoes. When it comes to man-made sources, PVC doesn’t even show up on the radar screen.

Dioxin is created during incomplete combustion of any material – even wood burning in a home fireplace. According to the EPA’s inventory of dioxin emission sources, total dioxin emissions dropped from a toxic equivalent (TEQ) of 13,949 grams in 1987 to 1,106 grams in 2004. The top four man-made sources are:

Backyard barrel burning 56%

Land-applied sewage sludge 6%

Residential wood burning 5%

Coal-fired utilities 5%

Vinyl is one of more than 20 sources that make up the “other” category. Individually, vinyl is less than 0.4% of the total – that’s less than 5 grams throughout the entire United States. Even if vinyl was not being manufactured and used daily in myriad essential and lifesaving products, the levels of dioxin in the environment would be essentially unchanged.

Let me know what questions or negative statements about PVC that you have been faced with and we’ll address them here. Email me at

Factors To Consider When Purchasing A Roofing System: Environmental Impact

The drive for environmentally-friendly products extends to the commercial construction arena, including roofing systems. In this post, we will discuss some of the energy aspects of roofing: reflectivity, emissivity, and the solar reflectance index.

Environmental Impact – Part B

Rooftop reflectivity has received substantial attention during 2009, perhaps most notably in Energy Secretary Steven Chu’s remarks recommending that the world’s roofs be painted white. The upshot is that a roofing material’s ability to reflect solar energy has environmental implications, including its contribution to (or mitigation of) the urban heat island effect and impact on emerging carbon markets, among others. In fact, a roofing system’s energy efficiency is really determined by a couple of interrelated attributes.

Reflectivity (technically, albedo) is the percentage of solar energy reflected by a surface. The higher the reflectance value, the more solar energy that will be reflected from the surface.

Emissivity is the measure of how effectively a material sheds the heat it has absorbed. Materials with a high emissivity value may absorb energy easily, but they also radiate large amounts of it back into the atmosphere.

Roofing systems that provide both high reflectivity and emissivity are most likely to have a significant impact on a building’s energy cost. Some systems can reduce a building’s energy consumption by up to 40%.

The solar reflectance index (SRI) is a tool that evaluates reflectivity, emissivity, and other factors to determine a roof’s overall ability to reject solar heat. Its calculation is defines by ASTM E 1980-01 and is based on a formula that includes values for solar absorptance, solar flux, emissivity, the Stefan Boltxman constant, and other coefficients.

Standard black (reflectivity 5%, emissivity 90%) has an index of 0, and standard white (reflectivity 80%, emissivity 90%) has an index of 100. Very “hot” materials can actually have negative values and very “cool” materials can have values greater than 100. Materials with the highest SRIs are the coolest choices for roofing.

The Duro-Last Cool Zone® roofing system, a PVC membrane, has initial reflectivity and emissivity measurements of 87.5% and 95%, respectively, and a resulting SRI value of 108.

Here are the SRIs of some other roofing materials as measured by Lawrence Berkeley Labs and the Florida Solar Energy Center:

Roofing System




White EPDM





Metal, White




New, Bare

Galvanized Steel




Light Gravel





White Granular

Surface Bitumen




Dark Gravel




Black EPDM




Is Roofing Part of Your Energy Management Strategy? Part 4

Single-Ply Cool Roofing Systems

Many single-ply roofing systems have become popular in commercial applications due to their long-term performance, easy maintenance, and life-cycle cost benefits. Some of them have emerged as the best long-term cool roofing options. Their common attribute: high reflectivity.

  • Polyvinyl chloride (PVC) single-ply roofing systems have the best track record of long-term performance among white single-ply cool roofing systems. The first white PVC systems were installed in Germany during the 1960s, and their overall performance and life cycle cost benefits made these early systems popular in Europe during the 1970s and ’80s.
  • Chlorosulfonated polyethylene (CSPE) single-plies were the earliest widespread white roofing systems in the U.S., introduced in the 1970s under the Hypalon® brand. Although effective as a cool roofing system, Hypalon has not achieved the same commercial success as PVC, EPDM and other single-plies.
  • More recent cool roofing single-ply developments include the introduction of thermoplastic polyolefins (TPOs) and certain new co-polymer alloys (CPAs) during the late 1980s and 1990s.

Today, many single-ply roofing systems are available in white, including EPDM and modified bitumen, but PVC and TPO systems are the most popular and best-performing in terms of long-term reflectance. The National Roofing Contractors Association (NRCA) has identified the PVC/TPO thermoplastic single-ply category as the fastest growing roofing sector in America for several years. The coolest among these systems typically have solar reflectance ranging from 70 percent to 85 percent.

Installing a single-ply cool roofing system can save energy and money for building owners all over the United States.

The Cool Roof Rating Council was created to develop accurate and credible methods for evaluating and labeling the solar reflectance and thermal emittance of roofing products. The CRRC’s web site enables you to search for rated products as you investigate roofing systems that will help make your building as energy-efficient as possible.

In our final installment we will discuss Regulatory Incentives and Mandates.

Positive Responses to Negative Statements About PVC: Part 5

Statement: “PVC building products create poisonous gasses when they burn.”

The facts: This is technically a true statement, but misleading, because it is true about all organic materials (containing carbon), whether natural or synthetic, and there are countless organic materials in every commercial building. The major gaseous products of the combustion of PVC are carbon monoxide, carbon dioxide, hydrogen chloride and water. Chlorine gas is never produced when PVC burns.

But unlike other building materials, PVC is resistant to ignition; most rigid and flexible PVC will not burn without the continued application of heat from another source. The temperature required to ignite PVC is more than 300°F (150°C) higher than that required to ignite wood. The potential for flame to spread from burning PVC is very low because it has a slow rate of heat release, and it does not drip when it burns; instead, it develops a char which inhibits the spread of flame.

When it comes to structural fires, the U.S. Green Building Council’s Technical and Scientific Advisory Committee (TSAC), in its February 2007 report, Assessment of the Technical Basis for a PVC-Related Materials Credit for LEED, admits that there are many sources of toxic gases besides PVC. The report advises that “any firefighter not using a breathing apparatus would be taking on unnecessary risk, regardless of the specific materials present.” There is evidence that – as do many other building materials – PVC may contribute to hazardous conditions in building fires. However, there is insufficient information to determine how widespread or consistent the risks are. The TSAC report goes on to say that “compared with other plastics, and other combustible materials, PVC may have a beneficial role in reducing injuries in structural fires, as it may reduce the chances of a fire igniting or spreading due to its relatively high ignition temperature.”

In our final installment, we’ll look at this statement: “PVC is the largest source of dioxin, the most poisonous chemical on earth.”

Is Roofing Part of Your Energy Management Strategy?

Significant Savings Drive Demand for Cool Roofing

Cool Roofing Options and Choosing the Best Cool Roofing System

There are two primary types of cool roofing products on the market today: (1) reflective paints and coatings; and (2) single-ply roofing systems. Paints and coatings based on either acrylic or elastomeric chemistry can be an effective short-term solution for reducing energy costs, but most facility owners looking for long-term, low-maintenance solutions opt for a complete single-ply roofing system.

Many roofing products are on the market, which can make choosing the right one a challenge. Fortunately, several objective tools are available to help with the process. Choosing a system from the approved list of products in the EPA’s ENERGY STAR® Roof Products Program or from the Cool Roof Rating Council (CRRC) ratings chart is a good way to narrow down the selection process. Products on the ENERGY STAR list undergo rigorous testing before approval to ensure that they meet the established standard for reflectance.

In addition, the ENERGY STAR Roof Products Program has developed an energy savings calculator that projects the potential savings from installing a cool roof compared with alternative “non-cool” systems.

Here is a short list of important factors to consider when selecting a cool roofing system:

  1. Reflectance/emittance performance, both initial and after three years.
  2. Long-term track record of durability and performance.
  3. A good warranty backed by a solid, well-established manufacturer.
  4. Climate and weather extremes in a given location.
  5. Maintenance requirements and ease of repair.

In our next installment we will discuss: Single-Ply Cool Roofing Systems


Positive Responses to Negative Statements About PVC: Part 4

Statement: “Phthalate plasticizers used to keep PVC membranes flexible are dangerous to human health.”

The facts: The Duro-Last membrane uses a plasticizer that has been determined to be non-toxic to humans with no negative environmental impacts. There is no reliable evidence that any phthalate has ever caused harm to anyone. In over 40 years of study and use, phthalate plasticizers have never been shown to cause harm to humans from their normal use. The Consumer Product Safety Commission has studied the use of plasticizers in vinyl toys and found no demonstrated health risk.

In the 1980s, some phthalates were shown to cause liver cancer in rodents when administered at high doses over long periods of time. Follow-up research showed that the cancer was caused by a biological process in rodents that does not occur in humans.

A study of questionable reliability claims a statistical relationship exists between phthalates and asthma, rhinitis and eczema. The study was found to be of poor quality and the conclusions to be based on assumptions unsupported by the evidence. The conclusions disagree with recent experimental evidence showing no immune system response of the kind associated with asthma. Many risk factors associated with asthma such as dust, molds, mildew, and dander were not controlled for and so could not be ruled out.

A study by Shanna Swan claimed that prenatal exposure to phthalates affected the reproductive development of infant boys. However, a review of the study by a leading scientific research firm found that the study researchers used the wrong statistical model to obtain results and the relationship claimed is not biologically plausible. When an explanation of the study methods and a set of the data were requested from Swan, the request was refused. The failure of a scientific study’s author to disclose data for peer review leads to suspicion about its reliability because scrutiny is part of any valid scientific process.

Junk science is often used to create an emotional connection with perceived facts. One way to fight junk science and maintain credibility is to require public disclosure of data.

In our next installment, we’ll look at this statement: “PVC building products create poisonous gasses when they burn.”