PVC Roofing FAQ

What does PVC stand for?

PVC stands for “Polyvinyl Chloride.”

What is PVC made from?

PVC is composed of two basic components: chlorine derived from common salt, and ethylene derived from natural gas. By taking these two components and adding other components, PVC can be made rigid, flexible or semi-flexible.  This is why PVC is considered one of the most versatile plastic materials.  

What is the difference between PVC, Vinyl & Thermoplastic?

The terms PVC and Vinyl are often used interchangeably.  PVC is short for Polyvinyl Chloride and Vinyl comes from the first word “Polyvinyl”.

What is the history of PVC membranes?

PVC was discovered accidentally in the 1920s when a scientist was searching for a synthetic adhesive.  Soon after the discovery, PVC was being used as shoe heels, shower curtains, wire insulation and waterproofing fabric for raincoats.

Around the ’50s and ’60s, methods for enhancing PVC’s durability opened the door to using PVC in other areas, such as the construction industry.  In 1962, a small Swiss-based company named “Sarna” (known today as Sika Sarnafil) developed the first reinforced PVC membrane - “Sarnafil.”  Sarnafil was used first as a temporary tent structure, and then shortly after to waterproof tunnels and roofs.

PVC products quickly became the popular choice in the construction industry; the plastic’s resistance to corrosion, light and chemicals made it ideal for building applications.  PVC’s low cost, versatility and performance make it the material of choice for industries such as healthcare, communications, aerospace, automotive, retail, textiles and construction, where it is the most commonly used plastic. Rigid as pipe or pliable as a sheet good, PVC is a true performer.

Old Sarnafil PVC Sheet Roof

At the EXPO 64 in Lausanne, Switzerland in 1964, PVC sheets are used for the first time as a roofing membrane on the tent-like pavilions.

What type of roof system is PVC considered?

PVC is considered a “single-ply” roofing system.  This is because the system only requires a single layer of membrane to keep the roof watertight.  Other systems, such as an asphalt-based “built-up” roof system (BUR), involve multiple layers of asphalt-soaked felt to make up the system.

Are PVC and TPO the same?

While PVC and TPO are both in the thermoplastic, single-ply roofing family, they are very different in their base chemical composition and physical properties.  They are also not compatible with each other.  PVC has been used as a roofing material since the 1960s and has over 50 years of proven performance.

50+ Years of Proven Performance

Sarnafil PVC Roofing Systems continue to "Stand the Test of Time." In this brochure, you learn about the proven performance of Sarnafil roofs over the years. 

 

50 Years of Firsts from Sika Sarnafil

We've accomplished a lot of firsts in the past 50 years. Download the brochure to see Sarnafil's achievements. 

How is PVC installed on a roof?

Both PVC and TPO can be mechanically attached (using plates and screws) or adhered to the roof substrate.  Unlike PVC however, TPO membranes do not adhere readily, especially with water based adhesives.  They also have higher coefficients of expansion and contraction resulting in much greater movement through temperature cycles.  Whereas adhered PVC roofs have performed exceptionally well over decades, the properties previously mentioned create challenges when adhering TPO.

PVC’s overlapping seams are “hot-air welded” together to prevent water from penetrating the building.  Once welded together, the seams are one of the strongest parts of the system and do not break down over time like other roofing systems that use glues, double-sided tape or asphalt to bond their seams.

What are the main differences between PVC and TPO membranes for roofing?

Aside from the different chemistries used to create the membranes, PVC and TPO have other important differences worth mentioning.  TPO manufacturers are still continuing to modify their formulations to try and achieve the required level of performance, while PVC has been performing very well for over 50 years.  PVC membrane’s resistance to fire performance is significantly greater than TPO membranes, as evidenced in the video below.    Another important difference is TPO’s sheet flexibility.  TPOs are much stiffer than PVC, making them harder for contractors to work with.  This is especially important when having to flash penetrations or any other detail work, possibly leading to areas not being watertight, and when working in colder weather.  For a complete list of the differences between TPO and PVC, click on the link to download the Sikaplan Versus TPO infographic below.

To learn more about the issues with TPO roof systems, read our TPO: Still a Work in Progress page.

Is TPO worth the risk?

Download our infographic that compares TPO risks with the benefits of PVC membrane.

Why do contractors prefer installing PVC?

There are many reasons why building owners choose to trust a proven PVC roof membrane over a TPO membrane.  One of the most important reasons is that most, if not all, TPO manufacturers are on their third or fourth formulation of membrane, while PVC boasts 50+ years of real world performance.  For a roofing contractor however, the reasons they prefer to install PVC over TPO have a lot to do with them being able to give you a water-tight system.

In general, PVC is a much easier membrane for the contractors to work with, even in cold temperatures.  TPO membranes are stiffer, making sheet handling and detailing more difficult, especially in cold weather. If the membrane is challenging to work with and a contractor needs to flash a penetrations or a wall/curb, it increases the risk of an improper application.

TPO also requires all cut edges of the membrane to be sealed from water migration, and seams are much more sensitive to probing.  All of this leads to extra time, money and an increased potential for mistakes.  When TPOs fail prematurely, contractors run the risk of tarnishing their reputation.  No contractor wants to get a call that the roof they installed has failed.  No matter what the reason, all parties involved usually take the blame.

Sikaplan vs TPO Adhered Comparison

Sikaplan Adhered Systems offer PVC performance at a TPO price. The installed cost is often less expensive than TPO resulting in savings of 50 percent!  

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Top 5 Reasons Sarnafil is Different From All Other PVC Roofing Membranes

  Sarnafil All Other PVC
Membrane Formulation 50+ years of creating the ideal blend of premium grade raw materials to achieve the industries longest lasting thermoplastic membrane Produced to meet ASTM standard
Proven Performance 50+ years Less than 40 years
Membrane Thickness

(Thickness Guarantee) 

Membrane will meet or exceed the thickness indicated on the package label

ASTM standard allows up to 10% less than labeled thickness
Third Party Certification BBA Certificates stating that Sarnafil membranes should have a life expectancy in excess of 35 years No other U.S. PVC membranes have a BBA life expectancy certification.
NSF/ANSI 347 Sustainability Rating Platinum (Highest Rating) Sarnafil is the only Platinum Rated Single-Ply Membrane