Are all white commercial roof membranes the same?
They may be similar in appearance, but the answer is no, significant differences exist that are important when considering the purchase of a commercial roofing system.
Installation cost, total system service life, annual maintenance requirements, and warranties all vary from system to system.
In this article, we will discuss and compare TPO vs PVC roofing systems. When referring to PVC roofing, we will specifically be referring to the Duro-Last PVC roofing system. It is important to be aware of the different benefits each system offers when considering a new flat or low slope roof system for your facility.
Quick Overview
| Feature | TPO | PVC |
|---|---|---|
| Material Composition | Made from a polymerized rubber blend (usually polypropylene and ethylene-propylene rubber). | Made from ethylene and chlorine, combined with plasticizers to improve flexibility. |
| Installation Ease | TPO is lightweight and easy to install. | PVC tends to be easier to install. |
| Failure Points | TPO is cut on-site, has more failure points and requires more seams, leading to more potential leaks. | PVC is pre-fabricated for your building, less seams, less failure points. |
| Service Life | TPO roofs typically last 15-20 years. | PVC roofing can last up to 30 years. |
| Initial Cost | TPO is more affordable up-front. | PVC is more expensive to install initially. |
| Long-term Cost | TPO is more expensive over 15 – 20 years. | PVC has a lower annual cost over 30 years. |
| Chemical Resistance | TPO is resistant to most chemicals and mold growth. | PVC is resistant to most chemicals and mold growth. |
| Flame Resistance | TPO is not flame resistant. | PVC is self-extinguishing and flame resistant. |
| UV Resistance | TPO has less UV resistance than PVC. | PVC reflects up to 85% of the suns UV rays. |
| Weather Resistance | TPO works well in most calmer climates. | PVC is wind-and-weather resistant, ideal for severe weather conditions and climates. |
| Overall Rating | ⭐⭐⭐⭐ 4/5 stars | ⭐⭐⭐⭐⭐ 5/5 stars |
PVC or TPO Roofing: Experience and Properties
The two most common white commercial roofing membranes available today are PVC (polyvinyl chloride) and TPO (thermoplastic polyolefin).
PVC roof membranes have the longer track record, coming on the market in 1966, but TPO has about half the field experience due to its later development in 1991.
Duro-Last is an excellent PVC roofing choice as they are the world’s largest manufacturer of custom fabricated PVC membrane roofing, with headquarters in Michigan and distribution centers across the U.S.
The Duro-Last PVC membrane consists of three layers, a top sheet, reinforcement scrim, and base sheet.
The top sheet, the layer above the scrim, is the performance layer that faces the weather, wind-blown dirt, airborne pollution, UV radiation, and foot traffic.
Duro-Last offers the thickest performance layer of any roof membrane on the market, providing an exceptionally long and essentially maintenance-free service life.
The middle layer of the three-part assembly is a weft-inserted, anti-wicking reinforcement scrim. The thread count and tensile strength of this middle layer is key to the strength and durability of the membrane. The scrim of Duro-Last’s flag ship membrane has the highest thread count in the industry at 18×14 threads per inch.
The third layer is the bottom or base layer. In most roof systems the third layer is made of less expensive material since it is not exposed to the weather.
Duro-Last provides two primary membranes, one with the same high quality top layer material in both layers (trade name Duro-Last, the flagship membrane first offered in 1978) and an alternate membrane with a lower cost base layer and reduced scrim thread count (Duro-Tuff, on the market since 2012).
Both systems provide excellent performance, but Duro-Tuff has a lower price point and is applicable in many situations.
Both systems, including other specialty products, are fabricated on state of the art laminating/extruding equipment at the Saginaw, Michigan headquarters.
Due to the chemical properties of the PVC system, PVC roofs are strong, flexible, inherently fire retardant, and resistant to most chemicals.
TPO has essentially the same three part structure but with significant differences in materials. Most TPO membranes consist of polypropylene, ethylene-propylene rubber, and various fillers such as carbon, fiberglass, or talc mixed with polymers.
When evaluating membranes of comparable thickness from Duro-Last or TPO, comparisons prove the performance layer in TPO is thinner than the PVC membranes, the scrim is not weft-inserted and typically has a lower thread count, and the base layer of TPO is a lesser quality material with a higher percentage of fillers.
The result is a product that is flexible and looks good, but has reduced puncture or tear resistance, will burn if exposed to flame, and is less chemically resistant than Duro-Last PVC membranes.
PVC or TPO: Sustainability
In 2009, the National Science Foundation created a new standard, NSF/ANSI 347 for measuring and evaluating the sustainability of single-ply roof systems over their entire life cycle.
Each single-ply roofing system is assessed in five areas: product design, product manufacturing, membrane durability, corporate governance, and innovation.
Duro-Last has been certified sustainable with five of their most popular membrane options for NSF/ANSI 347, including one gold and two silver certifications.
They have received recognition for the recyclability of their PVC membrane and their environmental product declarations. Upon the end of it’s useful life, the Duro-Last membranes can be returned to Duro-Last for recycling in house at their Saginaw Michigan facility.
TPO membrane recyclability is questionable and they have not earned the same certifications from the National Science Foundation.
PVC or TPO: Energy Efficiency
As we approach the summer months and temperatures rise, the roof you choose may make a substantial impact on the energy efficiency of your building and comfort of your staff.
To fully understand how a roof system can affect energy costs and building temperatures, we need to consider the Solar Reflectance Index (SRI) of PVC and TPO membranes.
The SRI measures how hot a roofing surface can become under full sun exposure. The SRI number for each roof type is measured when the membrane is new and again after three years exposure. The higher the number, the better the roofing material ability to inhibit heat transfer into the building.
The Duro-Last white 50 mil PVC membrane reflects up to 88% of the sun’s energy. The initial SRI is 111 and after 3 years it is measured at 82, primarily due to dust or air borne contaminants on the membrane surface.
For TPO, reports show an initial SRI of 77, with a drop to 70 after year 3. PVC membranes are more efficient at radiating heat away from the building instead of allowing it to pass through. Air conditioning has become the fastest-growing consumer of energy, and maintenance/replacement costs for A/C systems are climbing as well.
Choosing a roofing system with a higher SRI may help improve energy efficiency, help with longer A/C system life, and reduce energy and cooling system costs.
PVC or TPO: Installation Methods
Both TPO and PVC can be mechanically fastened or fully adhered, depending on the building structure and client preference. The difference between Duro-Last roofing systems and TPO is in field labor requirements and final quality of installation.
TPO requires that most flashing details be fabricated on site by field crewmen. Most leaks or roof failures are due to workmanship, from crewmen working outdoors dealing with the changing weather conditions including wind, threat of precipitation and temperature extremes.
Reducing field work requirements can help avoid future roof problems and reduce on site labor time and costs. Duro-Last provides custom fabrication of all rooftop flashing details and optionally, custom fabrication of deck sheets, done in house under ideal factory conditions at one of the Duro-Last facilities.
Every rooftop penetration and detail on your building will be measured by our project managers and the flashing components will be custom pre-fabricated, eliminating the need for complex flashing work in the field. You will receive a better, more reliable installation with Duro-Last custom fabrication installed by our experienced team of professional, courteous crewmen.
PVC or TPO: The Cost
Every project has a budget, it’s just a fact of life.
Two key cost components will be involved in your rooftop installation – on site labor and roofing materials. It is up to you as the building owner to decide what part of the roofing process you prefer to invest in – on site labor or material?
Labor leaves the job site when the job is done, but the material remains to protect your business, equipment, inventory, and staff. Duro-Last PVC prefabrication saves on site hours that TPO non-prefabricated roofing cannot.
The result? More of your dollars are invested in the roof system and less in the labor that drives away.
Other costs to consider are maintenance and service life. The least expensive roof to own is the one with the lowest annual ownership cost (cost of the project plus annual maintenance, divided by expected service life = cost per year to own the roof).
Investing more up front may result in the best return for capital dollars if the roof system will cost less to maintain and provide more years of service life.
Another factor to consider when comparing TPO vs PVC roofing systems are repairs or modifications that may need to be made over time.
PVC membranes may be repaired by the same hot air welding technique used in the original installations. TPO membranes become more difficult to work with as they age, making repairs or modifications more difficult and costly.
Give Sentry a Call!
Now that you know the TPO vs PVC pros and cons, you understand that choosing a roofing system and a roofing contractor are important decisions.
In our 35+ years in commercial roofing, Sentry Roofing, Inc. has completed successful roof installations in 40 states across the country. We roof facilities of all types and sizes, from smaller family businesses to vast warehousing structures.
If we are given the opportunity to meet with you, we will carefully inspect and evaluate your existing roofing system and structure and provide a detailed proposal tailored to your facility and needs.
We thank you in advance for the opportunity to meet, answer questions, and assist in any roofing needs you may have. We’re available at 800-446-2133.
Thank you for allowing us to be of service!
Frequently Asked Questions
Here are some frequently asked questions when comparing TPO and PVC roofing systems.
Will PVC weld to TPO?
PVC cannot be welded to TPO. Both PVC and TPO roofing can be welded, but since their chemical compositions are different, there would not be proper adhesion if you attempted to weld them together. Welding incompatible materials can lead to leaks.
Why should I choose Duro-Last PVC roofing systems over TPO?
Duro-Last PVC roofing systems offer superior puncture and tear resistance compared to TPO membranes. Duro-Last PVC membranes are also highly flame-resistant and self-extinguishing, providing enhanced safety for your building. Their chemical resistance surpasses that of TPO, ensuring long-lasting durability and protection for your roof.
How does the sustainability of Duro-Last PVC roofing systems compare to TPO?
Duro-Last PVC roofing systems adhere to the NSF/ANSI 347 standard for sustainability, guaranteeing an environmentally friendly choice for your roofing needs. This certification underscores the long-term eco-conscious benefits of opting for Duro-Last PVC membranes.
What sets Duro-Last PVC roofing systems apart in terms of installation?
Since Duro-Last PVC roofing systems are pre-fabricated in a controlled factory environment, it prevents on-site errors and has less overall seams than traditional methods like TPO. This means you’ll have a better fitting roof with less potential for leaks or torn seams.
How do the costs of Duro-Last PVC roofing systems compare to TPO?
While every project has budget constraints, investing in Duro-Last PVC roofing systems ensures long-term cost-effectiveness due to their durability and low maintenance requirements. The initial investment in Duro-Last PVC membranes translates into a wise financial decision over the life cycle of your roof.
