UPDATE: It has become increasingly difficult to find the MRCA T&R Committee TPO Advisory – in fact, MRCA has deleted it from their website (we believe this is due to pressure from big TPO manufacturers who do not want negative press). Here is the original of this document – MRCA TPO Advisory
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Original article: In the single ply roofing market, TPO roofing membranes are continuing to experience significant growth, competing for a share of the pie with both PVC and EPDM membranes.
While a TPO membrane roof is newest of all three membranes, officially introduced into the US market in the early 1990’s, its manufacturers have been working hard on developing a formula that would offer a competitive advantage in terms of longevity, durability and price over PVC roofing membranes.
It took more than a decade and a challenging process of coming out with 36 different ASTM drafts of an industry standard for TPO before finally in 2003 an ASTM Standard 6878 was approved.
The ASTM standard went through two more revisions in 2006 and 2008.
However, as recent as 2010, some questions still remained as to the longevity and durability of TPO membranes especially under conditions of heat and solar overload.
These concerns were first raised by the Midwest Roofing Contractors Associations Inc in their TPO advisory to the contractors in February 2010. This advisory drew a lot of attention and raised a lot of questions for professionals in the industry.
Subsequently, MRCA’s advisory was addressed by both Firestone Building Products (TPO membrane manufacturer) and by a panel on “TPO’s Long Term Performance” during MRCA’s 61st Annual Conference, held in October 2010.
Since this is the most recent update available on the state of TPO roofing membranes, it is important for roofing contractors and consumers who are considering installing a TPO membrane to be aware of this information, as this can have a significant impact on the decision whether or not to choose a TPO membrane for their roof.
Summary of the Original MRCA TPO Membrane Advisory
MRCA’s initial reason for issuing the TPO advisory to its members was the fact that the association got enough information from different sources in the field that indicated high solar and loading and elevated temperature lead to premature aging and failure of TPO membranes.
Specifically, thermal and solar loading lead to the premature exhaustion of anti aging components such as anti oxidants, UV absorbers and heat and light stabilizing compounds within TPO roof membrane.
This issue was particularly noted in the Southern states because many TPO membranes that have been locally installed were exposed to a level of heat load that they were not able to withstand. The advisory was issued on February 10, 2010.
The committee brainstormed specific suggestions on dealing with issues of solar and heat loading in working with TPO membranes:
1. Be aware of situations where sun light is reflected back on the TPO membrane; such as areas below metal and glass or highly reflective curtain walls, or high profile reflective wall flashings.
2. Look for heat emitting equipment or heat exhausting vents or dark emissive materials laid on the roof that further increase the temperature of the TPO membrane, as well as areas under or over elevated temperature operations.
3. If there is a situation where it is known ahead of time that there will be elevated temperatures over 160 degrees F or elevated solar load, it is best to question the TPO manufacturer whether their product can adequately withstand these conditions. It is also possible to consider alternative products that are known to withstand this loading, or alternatively consider changing roof design to forestall the loading.
4. If you have an existing TPO roof that is functioning under the conditions of elevated solar and heat load, it is advisable to inspect the membrane for incipient, developing or obvious local problems. Then, the membrane’s manufacturer should be approached for directive on how to best address or rectify the issue.
While no names of manufacturers or specific brands of TPO that have experienced these problems were revealed, MRCA did mention that one of the manufacturer’s was working to address this issue by changing the membrane’s formulation, another explicitly suggested not to subject its TPO product to high heat and solar overload, while other manufacturer’s issued no responses and took no action.
Summary of Firestone Building Products’ Official Response to MRCA’s Advisory
Quickly following MRCA’s advisory, Firestone Building Products which manufactures UltraPly TPO issued an official response to the advisory on February 19, 2010.
The company assured its customers that after conducting its own investigation, it was found that there was no evidence in the field that UltraPly TPO was experiencing any issues related to solar or heat overload.
The investigation was conducted based on internal records in on-going laboratory and field testing, customer feedback, and warranty records.
The company also stated that it has not changed the formulation for UltraPly TPO since its inception in 1998, testing the formula to meet the highest standards and to ensure that the membrane will remain durable even under extreme conditions.
More specifically Firestone assured its customers that UltraPLy TPO is able to perform in extreme high temperatures and solar conditions of deserts in the Southwest, the heat and humidity of the South, as well as in the cold climates of the North.
Its notable that no other US TPO manufacturer issued any official publicly available statement in response to MRCA’s advisory.
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We have an EPDM roof that needs to be replaced. We were thinking of going with TPO. We live in NM and are now concerned about the solar/heat. Is there a TPO product that is ok? And do we have to completely remove the EPDM roof before re-roofing?
I wouldn’t tpo in New Mexico. We highly recommend spray foam and a silicone coating. we local contractors and the lack of care by the city tpo is typically installed horribly and fails within the first few years.
I wouldn’t do spray foam roofing over TPO. Spray foam is much more dependant on proper application, and much more complicated to repair, if installer messes up.
TPO with all its negatives, is repairable by probing seams and re-welding them in 99% of the cases.
I would never foam over tpo the thread is about tar and gravel. Foam is by far the most easy trouble shooting roof on the market. It can’t unheard threw it, there has to be a crack to leak from. With a silicone roof coating it will out perform tpo for years you come
Hello, We have a built-up flat roof with composition membrane cap sheet material. Can we place the new TPO sheet over the existing roof — or do we first remove the old composition membrane?
Thank you for your assistance.
You can put TPO over – no need to remove. However, you DO NEED a separation layer – usually 1″ or more insulation or 1/2″ fiberboard. You also want to make sure there is no wood rot under old roofing material.
Living in a mobile home park in florida. I have not seen failing of TPO some u its were done 7 to 10 years ago. Interesting Thank You
TR … well first you would need to monitor the changes on all those roofs, which I don’t think you do. Second – mobile homes have “rounded” roofs … there is not standing water on them, so even if material is slowly degrading, water still runs off the roof fairly well. Third – it’s nearly impossible to track which TPO may be affected because there are so many manufacturers, with each having multiple formulations… for example let’s say we have 10 mfgs of TPO in US, and each went through at least 10 minor or major formulation changes in last 15-20 years… there are literally 100 different products … possibly more, as these manufacturers are doing field testing on client roofs 🙂 And I don’t think this field testing is very scientific – it’s not like manufacturers go and inspect every roof annually and track changes. Probably more like “if there are no claims – the product is good” 😀
thanks so much for your info. I’m trying to decide which material to use for reroofing my flat roof. this helped a lot. Looks like Firestone might be the one to go with. The building is in New Mexico. It seems though that GAF everguard extrme tpo will also with stand extreme temperatures. What do you think. Or is there some new info since you wrote this?
Based on my research and information I possess, I’d say go GAF, or even consider some PVC products as an alternative.
Let me know what you decide to do. Good luck!
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