PVC Roofing: Everything You Need to Know

As a building owner looking to replace your roof, you will likely hear much about TPO, the most popular commercial roof on the market. While TPO is an excellent system, it isn't suitable for all applications; you can run into serious trouble using it for specific applications, such as a restaurant or a manufacturing facility. 

One excellent alternative to TPO is PVC, another single-ply system that is much more durable. But how do you know if you need to spend the extra money on PVC? That's where GIDEON comes in. At GIDEON, we've installed millions of square feet of every roof system on the market, so we can help you understand which system will fit your unique needs. In this complete guide, we'll discuss PVC roofing, including:

1. What It Is
2. Pros
3. Cons
4. What Kind of Buildings Should Utilize PVC
5. Maintenance

What is PVC Roofing?

PVC roofing is a single-ply roof system, meaning it consists of a single layer of material known as the "membrane," which is rolled out over the underlying roof assembly (consisting of the decking, insulation, and cover board) and attached using adhesives, mechanical fasteners, or ballasts. The membrane is made from polyvinyl chloride, which you're probably familiar with in plumbing pipes. While the base material is the same, PVC roofing has numerous other additives that make it flexible (able to expand and contract easily with temperature changes), resistant to UV radiation from the sun, fire-resistant, and virtually impervious to many industrial chemicals. 

PVC was first used as a roofing material in Europe in the 1960s, became popular in the United States in the 1980s, and is now a go-to choice for industrial buildings due to its resistance to chemicals, grease, and other pollutants.

KEE Formula

The KEE formulation is a particular type of PVC membrane that deserves to be mentioned. Manufacturers have developed a special PVC membrane formulated with KEE (Ketone Ethylene Ester), a flexible, lightweight polymer that acts as a "plasticizer." Plasticizers are used in roof membranes to keep the material flexible enough to handle temperature changes and building shifts without breaking. Most plasticizers, however, are liquid, which means they can evaporate under long-term sun exposure, leaving the roof brittle and prone to cracking. KEE, however, is a solid, so it won't evaporate. Combining KEE with PVC increases the membrane's durability, flexibility, and chemical resistance. If chemical resistance is crucial to you, it's worth discussing KEE with your contractor.

Pros of PVC Roofing

Chemical Resistant

The primary reason PVC roofing is an excellent choice for industrial facilities is its ability to maintain integrity despite exposure to substances that would degrade or destroy other single-ply membranes, like TPO. The primary reason PVC is so chemical resistant is the chlorine base of the PVC polymer, which creates a dense and powerfully-bonded molecular structure that cannot be easily penetrated or broken down by other chemicals.

Chemicals that PVC is highly resistant to include:

1. Acids.
2. Bases.
3. Salts. PVC's salt resistance can make it a good choice if your building is on a coastline.
4. Animal fats and vegetable oils. This makes PVC an ideal choice for restaurants and food-processing plants.
5. Alcohols.
6. Industrial pollutants.
7. Jet Fuel. PVC roofs are resistant to jet fuel exposure if the membrane is made with the KEE formula.

It's essential to remember that while PVC will generally hold up well when exposed to these substances, excessively high concentrations and long-term exposure can gradually degrade the material, so exposure should be minimized when possible.

Chemicals PVC is not highly resistant to include

1. Ketones
2. Aromatic hydrocarbons
3. Oil & Gasoline. On PVC sheets without the premium KEE formula, gasoline will pull the plasticizers out of the membrane (which makes it flexible), causing it to become brittle.

These materials are much more likely to degrade the roof over time, and exposure should be studiously avoided.

Fire Resistant

Another feature that sets PVC apart from TPO is its fire resistance. Unlike TPO, which has less fire retardant than other systems (higher levels of fire retardant make TPO membranes brittle), PVC has a high level of retardant and generally holds up better in building fires than its more famous competitor. If you hold a piece of PVC up to a lighted flame for three seconds, the flame will quickly extinguish, leaving just a tiny corner of the membrane damaged. If you do the same with TPO, the flame will continue to burn through the membrane.

Similar Advantages as Other Single-Ply Systems

Like other single-ply systems, PVC is easy to install, holds up well in most weather, and is compatible with roof coatings and foam. For a more detailed discussion of these advantages, including a description of single-ply installation methods, refer to our Guide to TPO and the Pros & Cons of Elastomeric Roof Coatings.

Cons of PVC Roofing

Higher Cost Than Other Single-Ply Systems

If you look at the chart below, you'll see price ranges for various commercial roof systems. If you look at TPO, PVC, and EPDM (all single-ply systems), you can see they range from as low as $3.00 per square foot to as high as $15.00. PVC accessories, such as flashings, tend to cost more than other single-ply accessories, making PVC somewhat more expensive than TPO and EPDM. It will usually add $1 or $2 per square foot compared to TPO.

An important note on the chart below is that the most significant factor affecting the bracketed pricing is the insulation package, including whether insulation is added, how much, what kind, and how it is adhered to the roof substrate. The effect of insulation on pricing is extremely under-discussed by most roofers and is often responsible for significant differences in bid pricing among different roofing companies. To learn more about this, please see our article on How Roofers Reduce Bid Prices. 

Loses Aesthetic Appeal More Quickly

PVC will usually accumulate dirt and other detritus more easily than TPO. After a few years, it tends to look brown and stained, so if aesthetics are a major factor, you may want to consider either a different single-ply system or an additional roof coating for protection.

Best Applications for PVC Roofing

Great applications for PVC roofing include: 

1. Restaurants. In restaurants, grease gets taken up by the ventilation system and deposited on the roof, so a durable membrane is very important.
2. Food-processing plants. In many food processing plants, blood, guts, and other waste byproducts can accumulate on the roof. PVC will hold up well against these substances.
3. Industrial applications & chemical processing. As mentioned earlier in this article, PVC is very resistant to chemicals and is a great choice for industry.
4. Coastal buildings. As mentioned earlier, PVC is resistant to damage from salt, which can be deposited on the roof of buildings located on a coastline.
5. Airports. With the KEE formulation, PVC can withstand the jet fuel that tends to accumulate on airport roofs.

PVC Roofing Maintenance

Regular maintenance is important to make sure your PVC roof lasts. Ideally, the roof should be inspected twice a year by a professional who can catch any developing problems before they become serious. 

We recommend pressure washing the roof every 5-8 years to bring it back to a white color and expose any blemishes in need of repair.

The Upshot

There are so many options for roofing, from single-ply systems like TPO and PVC to roof coatings, spray foam, asphalt, and more. Wading through the options and selecting the right solution can be tedious, and a mistake can cost you hundreds of thousands of dollars. Now that you've learned about PVC roofing, we'd recommend hopping on a call with one of our GIDEON advisors. In a free 15-30 minute call, we can assess your situation and make customized recommendations for your building.