PVC ROOFING SYSTEMS

What is PVC Roofing?

What does PVC stand for?
PVC stands for “Polyvinyl Chloride.”

What is PVC building products made of?
PVC is composed of two basic components: chlorine derived from common salt and ethylene derived from natural gas. PVC can be made rigid, flexible, or semi-flexible by taking these two components and adding other elements. 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." Thermoplastic is the category type both PVC and TPO fall under as they are both a form of plastic. Products such as EPDM roofing fall under the Thermoset category type as they are a form of rubber.

What is the history of PVC Roofing?
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 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 Roofing membrane - "Sarnafil." Sarnafil was used first as a temporary tent structure and then shortly after to waterproof tunnels and roofs.PVC products quickly became popular in the construction industry; the plastic's resistance to corrosion, light, and
chemicals made it ideal for building applications. In addition, 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 a pipe or pliable as a sheet good, PVC is a true performer.

What type of roof system is PVC considered?
PVC is regarded as a "single-ply" roofing system 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.

What is the difference between a PVC and TPO roof?
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

How is PVC Roofing installed?
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 to TPO.

PVC Roofing's overlapping seams are heat-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 some other differences between PVC and TPO roofing?
Aside from the different chemistries used to create the membranes, PVC and TPO have
other important differences worth mentioning. TPO manufacturers continue 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 fire-resistant 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. 

Why do contractors prefer installing PVC Roofing?
There are many reasons why building owners choose to trust a proven PVC 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 the membrane, while PVC boasts 50+ years of real-world performance. For a roofing contractor, however, the reasons they prefer PVC over TPO installations has a lot to do with them giving you a watertight system.

In general, PVC is a much easier membrane for 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 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 reputations. 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.

Is PVC Roofing Durable?
PVC roofing systems have been around since the early 1960’s and used on every building type, in every climate imaginable.  Some PVC membranes have been third party verified to last over 35 years. 

What is the cost of PVC Roofing?
PVC roofing systems are an affordable option for any building owner.  For owners who are looking for long-lasting, top of the line performance, Sarnafil is the best option.  For owners who are looking for industry standard quality at a cost competitive price, Sikaplan would be the right fit for you.  No matter your budget and building needs, Sika Sarnafil has a system for you.