PVC vs TPO

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Author Message John Hunter Senior Member Username: johnhunter Post Number: 29 Registered: 12-2005 Posted on Tuesday, May 29, 2007 - 02:40 pm:    I've specified PVC roofs for years (Sarnafil) in a range of climates across the US with good success. However, recently a client has asked us to consider TPO instead, as they're trying to eliminate vinyl from their buildings. Also, they made it clear that, while they're asking us to consider this, they are not directing us to make the change. While my initial reaction is to not fix something that isn't broken, I do think I owe them a reasoned evaluation. So, does anyone have any experience that I can factor into the evaluation. This is an institutional project in northern California. Thanks. Ron Beard CCS Senior Member Username: rm_beard_ccs Post Number: 203 Registered: 10-2002 Posted on Tuesday, May 29, 2007 - 03:04 pm:    John: Check out "PVC vs TPO" in the 4Specs search engine and you will find several previous treads on the topic. Russell W. Wood, CSI, CCS Senior Member Username: woodr5678 Post Number: 87 Registered: 11-2003 Posted on Tuesday, May 29, 2007 - 05:00 pm:    We too are becoming part of the Green movement. I sit on a committee that deals with LEED, sustainable, and the like. I personally have no negative experince with PVC roofing...but our Green-nics on our committee have brought forward what they feel is sufficient data to cause us to remove PVC from our specs in favor of ETHYLENE INTERPOLYMER (KEE) ROOFING MEMBRANE and THERMOPLASTIC POLYOLEFIN (TPO) ROOFING MEMBRANE. Jerome J. Lazar, RA, CCS, CSI, SCIP Senior Member Username: lazarcitec Post Number: 377 Registered: 05-2003 Posted on Tuesday, May 29, 2007 - 09:08 pm:    Russell, is not PVC roofs like Sarnafil recyclable, would that not still make it a viable green product? Don't get me wrong I also like Fibertite, but I am curious why the negativity toward PVC membranes? Ronald L. Geren, RA, CSI, CCS, CCCA, SCIP Senior Member Username: specman Post Number: 470 Registered: 03-2003 Posted on Tuesday, May 29, 2007 - 09:21 pm:    Check out the information on the USGBC website. I believe the issue stems from the manufacture of PVC roofing and not the product itself. http://www.usgbc.org/DisplayPage.aspx?CMSPageID=153 John Bunzick, CCS, CCCA Senior Member Username: bunzick Post Number: 726 Registered: 03-2002 Posted on Wednesday, May 30, 2007 - 08:38 am:    PVC roofing is not particularly recyclable because the plastic cannot be separated from the reinforcing. The process of plastic recycling is not a fully realized one, which bothers me a lot. While many plastics are marked with a recycling code, many still are not--those maddening product bubbles are one. In addition, as far as I can tell a very large percent of recycled plastic is just mixed together and made into products that do not require much in the way of performance: decking, pallets and the like. Even when plastics are separated, the percentage used in production of new products is very small in order to maintain the engineering properties of the product. For example, according to one source, PET bottles use only 10% post-industrial waste and no post-consumer. What this means is that recycled plastic will still end up in a landfill once it cannot be recycled "again" into something useful. This is a serious long-term problem in the plastic industry, IMHO. Sorry, got off track. We've been successfully using TPO for a number of years for roofing in instutional environments. While there is still some maturation needed in the industry, we haven't seen anything to cause us great concern. Anne Whitacre, FCSI CCS Senior Member Username: awhitacre Post Number: 557 Registered: 07-2002 Posted on Wednesday, May 30, 2007 - 12:42 pm:    the old problem with TPO was that there was no consistency in the manufacturing of it; an ASTM for the membrane was finally introduced a few years ago. stick with the big manufacturers and get a warranty and you should be fine. the cost savings with TPO typically come because of a labor savings -- the sheet is 12 feet wide, not 6, so there are fewer seams in a typical installation. I would say also that the vinyl debate is not final at this point; even the USGBC has declined to take a stand regarding vinyl... and the vinyl folks are members of the USGBC. Phil Kabza Senior Member Username: phil_kabza Post Number: 258 Registered: 12-2002 Posted on Wednesday, May 30, 2007 - 03:33 pm:    If you are using a single ply membrane such as TPO on an institutional project because of budget limitations, that's understandable. However, if you are using a TPO or even a PVC or KEE in order to meet Energy Star or Title 24 requirements, do also consider BURs and MBs with their surfacing and coating systems that will also meet Energy Star and Title 24. Single ply membranes are still only single ply membranes, and do not have the durability, longevity and renewability that BURs and MBs offer. By the time you adhere TPOs, put cover boards under them, and buy decently thick membranes, they start to cost what the traditional and more substantial membrane systems cost. On no traffic roofs, they can do well. But on busy roofs - less may just be less. Above comments are as always moderated by regional installer issues and some climate issues as well. Anonymous   Posted on Tuesday, June 05, 2007 - 04:29 pm:    USGBC final PVC paper posted on their web site concludes that, for the products evaluated, PVC is only worse in the resilient flooring area, and better in the other areas studied. In the report you will also find information about PVC roofing, and more myths busted. I specified TPO membranes right up until I learned that a large manufacturer of this type of membrane was having to deal with several failures in southern climes. I moved decidedly away from TPO because of this and went back to PVC and PVC alloy membrane systems. I strongly disagree with Phil Kazba's statement above that single ply membranes do not have the same durability, longevity, and renewability as BURs and MBs. PVC and PVC alloy membrane systems have decades-long in-service histories. Check Sarnafil and Fibertite. Additionally, these membrane systems require much, much less maintenance over time than BURs and MBs. PVC and PVC alloy membranes are HIGHLY recylcable, and Sarnafil has recently adopted a policy to take back all membrane materials from contractors to recycle back into new membrane. Can BURs and MBs be reccycled? No - they are, at best, DOWNCYCLED - one step short of incineration/landfill. Disclosure - I am a seasoned, experienced full time specifier for a large A/E firm and not a product rep. I spec BURs, MBs, and single ply membrane roofing assemblies routinely. I am interested in truth and facts, not gossip and hyperbole. W. Dean Walker, AIA, CCS, SCIP Senior Member Username: wdwalkerspecs Post Number: 15 Registered: 08-2006 Posted on Thursday, June 07, 2007 - 05:46 pm:    I fully agree with the "Anonymous" answer. I have specified and have had installed many PVC roofs and none have ended up with a problem. I appreciate the information about the recycling that is being done by Sarnafil. Specifiers have misconceptions because of the shattering of the initial Trocal PVC roofing membrane of many years ago. Seems like every time we bring a successful product from Europe here - we have to re-engineer it to make it cheaper and it fails. Christopher E. Grimm, CSI, CCS, LEEDŽ-AP, MAI, RLA Senior Member Username: tsugaguy Post Number: 129 Registered: 06-2005 Posted on Tuesday, March 18, 2008 - 12:08 pm:    Regarding the USGBC's position, another paper that may give a more current, and more negative view of PVC from an overall environmental standpoint: https://www.usgbc.org/ShowFile.aspx?DocumentID=2372 See pages 5 & 6 (Pages 11 and 12 of the pdf) Their summary: "the available evidence indicates that PVC-based materials are consistently worse than alternative materials in terms of environmental and health impacts." But, I suspect there might be opportunity to further refine a lot of the sea water that goes into the production of PVC that is perhaps just considered a byproduct, and purify it enough to help with the water shortages...?