Single-Ply Roof Membrane Types: What Are They and How Do They Differ?

By Karen L Edwards 08-28-2020
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There are many roof membrane types to choose from, so how do you know which one is the right solution for your roofing project? The best way to start is by understanding the different types of membranes available. Here's an overview of the single-ply membranes you can choose from and the features of each system.

TPO Membrane

Thermoplastic Polyolefin, more commonly referred to as TPO, was developed in the 1970s. This roof membrane is known for being flexible and weldable with no plasticizers.

What to keep in mind about TPO:

  • TPO has excellent weathering characteristics and strong tear and break resistance.
  • Because TPO is typically white, it can also improve energy efficiency by reflecting heat away from the roof to keep it cooler.
  • TPO offers multiple installation options including adhered, mechanically attached, and in some cases, ballasted.
  • Not all TPO is the same. Manufacturing differences can result in varying performance. While the basic TPO polymer is generally the same across membranes, stabilizers and other ingredients may vary.
  • TPO seams are heat-welded together making the system watertight. This is an important difference when compared to EPDM, which has seams that are glued.
  • TPO has the largest market share of all single-ply membranes.

PVC Membrane

Polyvinyl Chloride (PVC) roof membrane is a reliable, versatile membrane that offers the flexibility of TPO with the added benefit of increased protection against chemicals. PVC is created from a hard solid that is made flexible with the addition of liquid plasticizers.

What to keep in mind about PVC:

  • PVC offers slightly more flexibility than TPO, making it easier to handle and install.
  • It has better chemical resistance than other single-ply roofing membranes, so it can withstand exposure to oils and greases longer than other membrane types. This makes it a preferred roof membrane type for restaurants and food manufacturing facilities. While PVC does have good chemical resistance, manufacturer's guarantees and warranties typically exclude from coverage damage caused by chemical exposure.
  • Just as with TPO, PVC seams are heat-welded together making the system watertight. This is an important difference when compared to EPDM, which has seams that are glued.
  • PVC is available in reflective colors to improve energy efficiency by reflecting heat away from the roof to keep it cooler.
  • PVC offers slightly less tear and breaking strength than TPO.

PVC-KEE Membrane

PVC-KEE membrane is PVC that is formulated with the soft, flexible polymer Ketone Ethylene Ester and fewer liquid plasticizers. PVC-KEE is manufactured with KEE, but still considered a PVC membrane when the amount of KEE used is less than 50 percent.

What to keep in mind about PVC-KEE:

  • PVC-KEE contains fewer plasticizers, helping to ensure that the membrane remains flexible over time.
  • The membrane offers greater tearing and breaking resistance than traditional PVC membranes.
  • PVC-KEE can be harder to weld. Extra time should be taken at the start of installation to double-check welder settings and ensure optimal welds.

EPDM Membrane

Ethylene propylene diene terpolymer is known in the roofing industry as EPDM and referred to by many as rubber roofing. It is manufactured using derivatives of oil and natural gas and is available in both black and white.

What to keep in mind about EPDM:

  • EPDM is a durable rubber membrane that has been performing well on low-slope roofs for many years in a wide variety of climates.
  • An EPDM system offers contractors multiple installation options, including ballasted, mechanically attached, or adhered.
  • If the membrane is exposed to chemicals or greases on the rooftop, it may degrade and become more susceptible to damage or punctures.

Deciding on a System

Ultimately, the system you choose will be dependent on factors like the building's location, its use, and your desired guarantee or warranty. To learn more about the system that will meet the needs of your unique project, reach out to the roofing experts at GAF.

ABOUT THE AUTHOR
Karen L. Edwards is a freelance writer for the construction industry and has a passion for roofing, having worked in the industry for 20 years.
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