2013 just rolled around, and many business and homeowners who are looking to replace their old roofs will have to balance between a number of factors, such as cost, expected service life, durability, and energy-efficiency when comparing different roofing products. This dilemma remains particularly stark in the flat roofing market, where the competition between PVC and TPO roofing materials is going strong, with no clear winner in site. However, there are some important trends in the TPO roofing market that can help you figure out whether this is the right roofing material for you.
No Recent Updates or Revisions of ASTM Standards (very technical)
One of the major issues with TPO roofing membranes was premature aging and seam failures due to prolonged exposure to intense heat. TPO roofing failures were particularly frequent in the states that experience the most heat and UV radiation all year round. These failures sparked serious concerns from MRCA and NRCA / NRCC, both of which issued advisories back in 2010 and 2011 urging roofing contractors to be aware of these issues and take extra precaution when installing TPO membranes. Moreover, MRCA called a panel of TPO manufacturers to take a closer look and discuss these issues. Since TPO was documented to be experiencing major issues, it would be expected that both organizations would continue to periodically issue updates for roofing contractors. However there have been no updates since the dates of the initial advisories and discussions (about 2 years).
ASTM International was also closely involved, and worked on testing the membrane, and revising and improving standards for TPO formulations. The last revision of ASTM D6878 TPO standard, dates back to 2011, at which point the organization stated that further tests and research will be conducted and more updates will follow. However, it has been almost 2 years, and ASTM has not issued any updates.
In a nutshell, latest revision of ASTM standard (Revision D6878-11a) required the top ply (weathering surface) of TPO membrane to be increases by 25% from 12 mil to 15 mil (15 mil = 0.015″). A typical TPO roof installed today is 60 mil in thickness, thus even by new standards, the weathering surface of the membrane is still only 1/4 of total thickness. However, in the standard’s review article by RCI, the conclusion is that 15 mill is sufficient, and 25% thickness increase provides exponential (not linear) growth on increased membrane life – source. Do note however, that this report was written by two Carlisle Syntec employees, which is a major manufacturer of TPO in US, and therefore is “somewhat subjective”.
Other “post-ASTM-revision” concerns that we have are: when will the new standard be applied in the manufacturing process, and how will it affect the cost of TPO roofing membrane?
1) How do you know if the material installed on your roof was manufactured after “D6878-11a” was issued and meets that standard? Many suppliers are sitting on excessive inventory of “old” materials, and will want to get rid of it as fast as possible.
2) Contractors will want to buy seemingly inexpensive materials, without any concern for which generation it is. Most contractors do not even know anything about these standards.
3) The cost of TPO that meets D6878-11a revision will increase drastically. Manufacturers will have to use significantly more expensive raw materials in the top ply. The bottom ply has no UV or weathering stabilizers, as it is not exposed, and therefore is much cheaper per 1 mil to produce. Hence the bottom ply is so much thicker than the top ply (cost cutting and maximizing profits). How will this affect the final cost to consumer?
Lack of information from TPO manufactures:
TPO roofing manufactures have not posted any new information on their websites about TPO performance, simply ignoring the issue. The only company that addresses durability and performance of TPO in detail and provides assurance of their product’s quality is Versico ( a private label for Carlisle). The company provides in depth educational information on TPO for their clients ( source ), which is in sharp contrast to the minimal information found on other manufacturer’s sites.
Finally, a Google search on “TPO roofing” and related keywords returns no posts in the last 12 months that would address the issue and shed light on whether TPO membranes have been performing well. You do however get many generic articles extolling the benefits of TPO as a durable, inexpensive and energy efficient roofing material.
Savvy consumers should wonder whether this overall silence means that the problems have been addressed, or that they are being swept under the rug, because TPO roofing is such a lucrative and profitable business.
Growing Popularity of TPO roofing membranes
It is important to note that TPO continues to grow in popularity both for commercial and residential applications. Currently, TPO is the fastest growing segment in the commercial roofing industry. There are two factors that account for this:
1. Increased demand for energy efficient roofing materials
2. Relatively cheap cost compared to its direct competitor, PVC membrane. Increasing number of consumers are realizing that they can save a significant amount on their energy bills and help the environment by installing cool roofs that are Energy Star Rated.
TPO is designed as a white, solar reflective membrane and is Energy Star rated, rightfully attracting consumers. Its direct competitor, PVC membrane, is also an Energy Star rated, white cool roof, but it can cost almost double the price of TPO. Naturally, more consumers who are looking to save money or have a limited budget will chose TPO over PVC (a more expensive, but time-proven single ply roofing system), since both roofing membranes offer very similar features and benefits.
PVC membranes have a proven track record of performance for over 30 years, with no recent revisions in the membrane’s formulation. At the same time, lack of information on problems with TPO also contributes to the fact that most consumers cannot distinguish between the two products, and go for the cheaper option.
In the interest of full disclosure and transparency, PVC membranes did have several serious failures in its early days in the 80′s when US manufacturer TROCAL produced an unreinforced sheet that would freeze and glassify in severely cold temperatures, and could shutter on impact( falling branch, tool, etc).
According to several former Trocal managers, the shattering problem mostly affected the PVC membrane imported from Germany – not the sheet produced by Trocal in US. Trocal contained the shattering issues before it was bought by John’s Manville. The buyer took care of all the outstanding warranties. No other major PVC failures have been recorded. Many TROCAL roofs are still in service and are completely watertight.
Here is a showcase of recent TPO roofing projects across the US:
Commercial Facility, Leominster, MA
Boys and Girls Club, Fitchburg, MA
Apogee Instruments, Inc. Utah
UFCU Disch–Falk Field, University of Texas at Austin
Exeter Hospital, Exeter, NH
Do your homework
If you are interested in installing a TPO roofing membrane, it is imperative that you get the best product and a reputable roofing contractor who specializes in installation of TPO. Especially if you live in a state that experiences high temperatures, take the time to talk to different roofing contractors and ask what has been their experience with TPO: repairs, problems, material failures, etc. Also, call different TPO manufacturers and do research on their websites. Overall, it is best to get a TPO membrane from a manufacturer that has been in the business for at least 15 years. Doing your homework will enable you to save money and get a roofing product that will serve you well.