TPO (Thermoplastic Polyolefin) – Commercial Roofing
What is TPO?
Thermoplastic Polyolefin (TPO) is a single-ply reflective roofing membrane made from polyprophylene and ethylene-propylene rubber polymerized together. It is typically installed in a fully adhered or mechanically attached system, allowing the white membrane to remain exposed throughout the life of the roof. The first sheet of TPO roofing membrane was installed in 1989 and since then millions of square meters of TPO has been installed worldwide.
A TPO roofing membrane is made from ethylene propylene rubber. Special technology is used to chemically bind together, rubber, ethylene ( an organic gaseous substance) and propylene (a byproduct of petroleum refining). At the end, numerous filler materials are added, such as talc, carbon filler and fiberglass. These fillers reinforce the TPO membrane’s strength and durability. A TPO roofing membrane has been specifically designed to have the advantages of a rubber roof, combined with hot – air weldable seams for extra durability. TPO roofing membranes have been manufactured in the US since the early 1990’s and are now the fastest growing segment of the US single-ply roofing industry.
Cooling Degree Days
TPO roofing membranes are highly attractive in regions with more cooling degree days – when cooling equipment is used – than heating degree days. TPO membranes reflect UV radiation keeping the surface of the roof and the building cool during summer months. This helps reduce cooling costs, and also decreases the amount of carbon emissions.
Reflectivity & Sustainability
Many companies and organizations are thrilled with the environmental benefits of TPO membranes. The Earth Rangers Centre (ERC) in Woodbridge, Ontario installed an UltraPly™ TPO roof on their office building, which is currently one of the most energy efficient buildings in Canada. Operating at less than 9kWh per square foot, and using nearly 90% less energy than other buildings of its size, TPO provided the reflective roof that works in conjunction with skylights and solar panels that helped ERC reach that impressive level of sustainability.
TPO vs PVC Roofing – The Pro’s & Cons of TPO Roofing
Over the last several years, it seemed as if TPO supporters have wanted to push the membrane onto every roof. Certainly the material has done very well and gained a large market share. But other membranes haven’t gone away, and some have a fairly stable market share. It’s easy to understand why single ply hasn’t done well on smaller roofs in urban areas, with their large numbers of penetrations and often chopped-up shapes; for these roofs, mod bit (or possibly a coating system) seems like an obvious choice.
What about PVC? It has a similar reflectivity to TPO and was the original weldable sheet. But there were questions about the plasticizers; what happens as they migrate out of the sheet? TPO was seen as being inherently flexible; over the years, it’s proven itself and has steadily improved in terms of weathering resistance. Manufacturers have been investing heavily in TPO but, surprisingly to some, PVC remains a viable alternative. In fact, we are starting to see investment in new capacity.
Let’s look at a comparison of the performance of the two sheets:
In terms of weathering (i.e., based on the Heat Aging and the Accelerated Weathering tests), TPO has the clear edge over PVC. This may surprise some diehard PVC users, who may be unaware of the advances made in TPO formulation over the last several years.
While TPO has superior weathering and slightly better tear and break resistance than PVC, PVC does have some characteristics that certain customers need or prefer. For example, PVC has better chemical resistance; it does not absorb or get weakened by oils and greases. This means that PVC is the preferred membrane for restaurants and other buildings that have grease traps on the roof.
Also, PVC is slightly more flexible than TPO, which some contractors like. There used to be talk about welding differences, but both membranes weld well. TPO requires higher temperatures but, once a crew has adapted, welding is as straightforward as it is for PVC.
The following chart gives a snapshot of the overall performance of TPO versus PVC:
So next time you’re debating which product would work best for an upcoming roofing job, it may be helpful to refer to the two charts above before you make your decision.
Contact The Eagle Roofing Company at 817-507-8152 & let us schedule a free roofing inspection or commercial roofing bid for you!
Their responsiveness, timeliness and quality of workmanship is unmatched in the roofing industry.
Chris Cartwright – President of Gregg Construction Co.