As the most trusted single-ply thermoplastic membrane manufacturer in the world, Sika is dedicated to educating its current and potential customers about the differences between PVC and TPO systems.
This page acts as a one-stop shop for all things PVC vs. TPO. Take a few minutes to research the issues that plague TPO systems, and how those problems can be avoided by using a PVC system instead.
Sikaplan vs. TPO Water Absorption Test
Is a roofing membrane's ability to wick water important? You bet it is! Water absorption of a roofing membrane can affect the quality of seam welds and lead to premature membrane failure, among a host of other things. In this water absorption test between Sikaplan and TPO, there is an obvious winner.
what others are saying about TPO
Over the past 20 years, TPO has grown to become one of the most commonly used low-slope, single-ply roof membranes thanks in large part to its low price point. What you might not know is that most, if not all, TPO membrane manufacturers are on their second, third or even fourth generation of membrane formulations due to performance inconsistencies and many are still having issues.
In fact, it's all anybody seems to be talking about...
Below are excerpts from various presentations, articles and design guides:
TPO MEMBRANES: WHY PERFORMANCE MATTERS
Presented by Rene Dupuis and Helene Hardy Pierce at the 2015 International Roofing Expo
- Throughout 2013 and early 2014, Structural Research, Inc. (SRI), a well-known and highly respected laboratory that has done testing with UL, NRCA, and MRCA, independently obtained various rolls (a total of 45 in all) of all of the major TPO brands
- SRI conducted a variety of ASTM physical property testing including thickness above scrim and weld strength which showed that the four TPO brands exhibit relatively similar performance on these tests. It wasn’t until accelerated aging using heat aging, weathering, and weight loss tests — the tests most closely associated with long-term membrane performance — were conducted that the various TPOs exhibited significant differences.
- In the overall thickness test of the 60 mil TPO membranes, the average thickness of each product was 55-57 mils.
- When looking at many physical properties such as thickness above scrim and weld strength, the four TPOs are quite similar. However, there are big differences in accelerated aging.
- It is reasonable to expect that membranes manufactured by an individual manufacturer should be relatively consistent from one production run (or from one plant) to another. However, the study found that some brands perform much more consistently than others.
GENERAL MOTORS FACILITY ENGINEERING
- From their conception, TPOs have and continue to be experimental membranes. They are all in their 2nd, 3rd and in some cases 4th generation of formulations.
- TPO itself is not fire resistant and requires the addition of fire retardants to obtain a fire rating. The ratios of weathering material and fire retardants are still inconsistent from manufacturer to manufacturer.
- GM has evidence of premature deterioration of TPO’s (Mexico) and the Roofing Contractor’s Institute has ranked TPO’s very high on the singly-ply membranes most problems list. There are welding inconsistencies, PVC installers switching to TPO’s have encountered issues, visual assessment of the quality of the welds not apparent, etc.
- GM will be reconsidering limiting the use of TPO’s only on very short life cycle facilities or 10 years performance or less.
TPO MEMBRANES AND PERFORMANCE: WHAT’S THE REAL STORY?
Presented by Dr. Kimberly Deaton-Tokarski, Johns Manville TPO Product Manager, at the 2014 RCI Winter Workshop
TPO Failures Recap
- Thermal Stability, mid-1990s: Membranes got too hot for too long
- UV Stability, circa 2000: Fire retardant ate up the UV stabilizer
- Solar Impact: UV and thermal failures caused by need for more stabilization
UNITED STATES DEPARTMENT OF DEFENSE
UNIFIED FORCES DESIGN CRITERIA
- Thermoplastic Polyolefin (TPO) shall only be allowed on roofs with an anticipated life of 10 years or less.
- TPO membranes are a relatively new roof membrane and have seen several reformulations in the past decade. Since they are new, long-term performance is unknown at this time. TPO should be specified with caution and only with 72 mil minimum thickness.
Authored by W. Blake Talbott – BBH Design Advisory – 2011
- TPO membranes have shown no consistency relative to failure mode. It fails in less than one year and up to 10 years plus.
- A vice president of one of the largest roofing contractors in North Carolina: “We are seeing a lot of failed 45 mil membrane roofs and expect the 60 mil roofs to follow soon.”
- Once the top layer has eroded, it can be a matter of days or a month and you can have a crisis mode.
A CRITICAL REVIEW OF THE LIFE SPAN OF TPO, PVC AND OTHER SINGLE PLY ROOF MEMBRANES
Presented by Karim Allana of Allana, Buick & Bers at the 2011 RCI Winter Workshop
- Allana highlighted a number of projects at the University of Nevada-Las Vegas where 11 TPO roofs had been replaced over the previous three years. All of the roofs were less than 10 years old. Allana went on to note that one roof had failed after just three years. It was replaced with a new TPO membrane from the same manufacturer, but was failing again 2½ years later.
BENCHMARK PERSPECTIVES NEWSLETTER
Volume 66: May 2010
- In our view, thermoplastic polyolefin (TPO) membranes have an uneven performance history. We have first-hand experience with some mid-1990 TPO membranes that had problems with welding, even when new. We have seen many TPO roofs less than 10 years old with serious levels of membrane deterioration.
- Our investigations of our clients’ roofs continue to identify issues with some TPO membranes: splitting and crazing along rows of fasteners, accelerated aging along walkpads, polymer erosion to the point of exposing scrim reinforcement; enough issues for us to have concern.
- We still have serious questions about the TPO products. Which manufacturers’ formulations will survive, how long will they perform, and what will eventual failure look like? Until we know the answers to these questions, we will be taking a conservative approach to thermoplastic polyolefins.