Letters

TPO sector reacts to article

The board of directors of SPRI, the trade association representing manufacturers of flexible membrane roof systems and related component suppliers, would like to respond to "Thermoplastics 101," June issue.

We feel the article is full of significant inaccuracies and, in some sentences, completely wrong information. The article does not appear to have been vetted properly, and we believe it is misleading to the uninformed. As a trade association, SPRI is available to assist in the vetting process by providing technical input on articles. We are disappointed this did not occur in this instance.

SPRI requests Professional Roofing publish an acknowledgement of the technical errors contained in this article.

James Rubenacker
SPRI president
Mike Ennis
SPRI technical director

This letter is in response to "Thermoplastics 101," June issue. We disagree with the characterization of the research work conducted by Structural Research Inc., Middleton, Wis., and sponsored by GAF, Parsippany, N.J. In fact, the research concluded TPO membranes generally show a level of product durability not seen 10 years ago, and improvements have been made to raise the performance of these products in service, especially their performance under temperature loading.

To suggest, as this article does, that any membrane will perform "if a building's roof frequently gets hotter than 275 F" is absurd.

We respectfully suggest anyone interested in the performance of thermoplastic membranes refer to the significant body of work that has been presented during the past 25 years and not rely upon the interpretations provided in this article that clearly are lacking. Specifically regarding our work, the results of the Structural Research TPO study can be found at www.gaf.com.

Rene Dupuis
Structural Research Inc.
Helene Hardy Pierce
GAF

Contrary to Allison Reinert's apparent intention to educate customers about thermoplastic roofing, she ends up confusing them throughout her entire article, "Thermoplastics 101," June issue. It appears limited research was conducted, and her lack of knowledge about the subject is evidenced by the numerous false and misleading pieces of information she provides.

For example, she states: "Although black and gray are the most common colors, PVC membranes are available in a wide range of colors." In fact, white is by far the most common color, and PVC is not sold in black. Similarly, TPO membranes have not been available in black for a decade or more, and black TPO membranes clearly could not "allow the same potential energy savings as a white roof" even if they still were available. Although she correctly notes TPO membranes can be ENERGY STAR^®-rated, she neglects to highlight the same is true for PVC membranes. Without context, the statement "(TPO) roofing also is 100 percent recyclable" is meaningless.

It is unfortunate that with regards to recycling, she appears to be oblivious to the fact that PVC materials have been recycled for decades both pre- and post-consumer, and that the most successful, prominent end of service life take-back and recycling program, which has been in place since the mid-1990s in Europe and since 2005 in the U.S., has recycled close to 60 million tons of pre- and post-consumer material combined back into roofing membranes.

"The drawbacks" section is particularly confusing in its discussion of "coating during maintenance," which, of course, is not part of any thermoplastic membrane manufacturer's "maintenance program." She highlights a potential aging mechanism for PVC membranes without describing the aging mechanisms of TPO membranes, implying a potentially inherent benefit, which runs contrary to the author's acknowledgement that "PVC membranes now have the longest track record of any type of thermoplastic roof membrane," and her assertion that with regard to TPOs, " … research regarding the best formulations for durability is ongoing."

Although we appreciate her recognition of PVC membranes being potentially better suited for roofs exposed to high temperatures, "[i]f a building's roof frequently gets hotter than 275 F … " the building owner should be concerned about much more than the membrane as numerous studies have shown a white or light-colored reflective roof membrane may reach a surface temperature between 125 F and 135 F while a dark color may reach surface temperatures around 170 F.

Although there are numerous other errors throughout the short article, these alone are more than enough to demonstrate how poorly researched it is. It is surprising and disappointing that an article with so many blatant errors managed to make its way through Professional Roofing's editorial review and was published. Contrary to the author's suggestion, the information presented should never be used to "help guide your conversations with customers working through their research-gathering and decision-making processes" as it could only result in confused and misinformed customers.

Michael Darsch
Sika^® Sarnafil Inc.

Professional Roofing responds: Thank you for your letters. To clarify the discrepancies in the article, SPRI will be authoring an article for our October issue, and we look forward to working with SPRI to provide the most current and accurate information about single-ply roofing.

Global Cool Cities Alliance reacts to article

Maciek Rupar's article, "Not as cool as advertised," June issue, describes an analysis that compared aged ratings performed using Cool Roof Rating Council (CRRC) standards to conditions on in-service roofs of varying ages. I don't see any major problems with the studies or their methodologies.

However, the author concludes the article with a recommendation to apply a blanket "adjustment" to CRRC-aged ratings that is premature. The study sample size (90 roofs nationwide) simply doesn't provide enough diversity in geography, roof location and product category to make the type of adjustment called for in the article. For example, the author is suggesting a reflectivity downgrade to all PVC roof membranes based on the analysis of just 16 roofs nationwide. Although it may be sensible to consider a "real-world" adjustment in the future that is specific to geographies and product types, we do not yet have the data to do it properly.

Kurt Shickman
Global Cool Cities Alliance executive director

Rupar responds: Thank you for your letter. We stand by the recommendations in the article. Our proposed adjustments to the CRRC's reflectance values of reflective single-ply roof membranes as a category and reflective PVC roof membranes as a subgroup were based on the same practices CRRC has been using for its roofing product rating program—using exposed samples from limited geography (three sites) and then applying them to the entire U.S.

In addition, your concern about the number of PVC samples is statistically unfounded: Consider a CRRC reflectance rating is based on an average reflectance value of just nine exposed specimens. We encourage you to review "Field Measurements of Solar Reflectivity for In-Service Single Ply Roof Membranes," Winter 2017 Conference Proceeding, ASHRAE, available by clicking here.

Maciek Rupar
NRCA director of technical services
Matt Dupuis, Ph.D., PE
SRI Consultants