Commercial Roofing

EPDM Roofing Vs TPO Roofing Vs PVC Roofing-Who Will Win Over the Flat Roof Industry?

By November 15, 2022 March 14th, 2024 No Comments


What are the Different Types of Flat Roof Materials?

With so many options to choose from, it can be hard deciding on just one material for your next roofing job. But don’t worry! We’re here with everything you need know about single-ply membrane roofs and their benefits as well drawbacks in order help guide that decision making process effectively down the road.”

Single ply membrane roofs come in three different types: EPDM, TPO and PVC. They offer a variety of benefits depending on what you’re looking for with your commercial building’s roofing system – from water resistance to energy efficiency.  However, these materials do have their drawbacks too like increased costs due availability or specialized labor and equipment needed to install.  In Colorado, all three roof types are used regularly and the deciding factor could come down to the contractor that you are talking to. Commercial roofing contractors tend to have a preference on what material they believe is best.  

What Goes Under the Roofing Materials?

The single ply membrane roof is composed of sheets of roofing material that usually come in large twenty foot rolls.  The sheets are cut and handled by the roofers and eventually chemically adhered to the coverboard.  Interestingly, when a roof is mechanically fastened, this refers to the coverboard that serves as the substrate to the roofing material being fastened to the roof deck using screws.  The roof membrane, whether it be EPDM, TP, or PVC is adhered to the overboard with a very strong bonding agent or roof adhesive that is designed by various manufactures and is specifically made to adhere roofing membranes to the roof overboard.  Each membrane has a specific bonding agent that it requires so it’s important that you work with a contractor with the technical expertise of using bonding agents. 

All three types of roofing membranes require a overboard. There are different types of coverboard but a very common and widespread brand is called Densdeck.  Densdeck is a cementitious material, meaning it is uses concrete, wood fibers, and other treatments to produce a fire resistant sheet of material that can help a building attain a fire rating.  This material can still catch on fire but it is more resistant that if the coverboard was made out of only wood.  It’s important to be aware of local building codes because a fire resistant coverboard is often required and it should be verified with photos or videos that a contractor did indeed use a fire resistant coverboard.  The overboard is fastened using specific anchoring screws and there are several types of patterns that can be used to fasten the board according to manufacturer specifications.  Some manufactures require additional screws when there is an extended warranty or NDL (no dollar limit) warranty being offered.  A no dollar limit warranty means that if there is a product or workmanship defect then the manufacturer will have the problem resolved no matter the dollar limit.  Some contractors may offer a wood only coverboard in order to be cost effective and competitively priced, but as an experienced contractor I would not recommend that.  If saving money is important then a building owner can use 1/4” cementitious coverboard rather than 1/2” coverboard.  Depending on the size of the roof, this small difference can make a big difference to the budget and it can usually still have the same warranties as using the 1/2” board. 

What is Roof Insulation?

Another aspect of these materials is that all three are compatible to roof mounted insulation.  Modern day building codes require that a roof be insulated. A roof can be insulated by having insulation inside of the roof cavity, meaning having insulation between the interior ceiling and the roof deck, or the insulation can be roof mounted. Another purpose of the insulation is that it can serve as a water shedding tapered system.  Buildings are designed to either have a structural slope, or they get a slope using a tapered insulation system. Older buildings often have a structural slope because roof mounted insulation is a relatively newer product gaining momentum over the last twenty years. Prior to tapered insulation, it made sense to an architect to design a structural slope to allow water to shed off of the roof and into a drain or gutter and then insulate the building in the cavity. As building materials developed, it became easier to design a flat roof and have the water shed with materials that had both an insulation value and a water shedding capability. 

A Closer Look At EPDM

Let’s take a closer look at EPDM roofing, also known as rubber roofing. When the Middle East oil embargo hit in 1970, many people were left without a roof over their heads. Asphalt based roofs became too expensive and low quality ones weren’t available at all; this led to an increase of popularity for EPDM single-ply membranes like those made by Firestone since they could provide both cost efficiency as well hail resistance without sacrificing anything else such UV stability or weathering characteristics.  Enhancements have been made not just within system components but also how these elements interact with each other so today’s systems are far more robust then before while still remaining highly valued among building owners.

EPDM roofing comes in 45mil, 60mil, 90mil, and even 120mil. It has become standard practice among manufactures to have an external fleece backed membrane to create even more puncture resistant. A 60mil fleece backed EPDM sheet is difficult to tear and puncture. Have a contractor give you a sample so you can hold it in your hand and feel it’s strength. The use of pressure-sensitive EPDM flashing was introduced in the 1980s. This product offered improved weathering properties and no cracking issues like with previously asphalt based materials.  EPDM also had a much more simplified application process as compared to asphalt based roofing that made quality assurance and labor costs decrease dramatically. Nowadays’s 60 mil layer laminated between 30 makes up an impressive 90 millimeter total thickness – providing more durability while also increasing robustness.

From 2005 onwards, seam sealing technology advanced to the next level with EPDM sheets and factory-applied tape. With this innovation contractors simply apply primer on one side of an unprimed piece before mating them together using a roller application process that reduced workmanship issues while also improving quality because the seam strips were pre-cut for you saving an enormous amount of cutting time in the field. 

For these reasons, EPDM tends to be the most cost effective roofing materials and although a twenty year warranty is standard with most EPDM roofing products, they have been known the last thirty or even forty years. To this very day, EPDM rubber roofing continues to be a favorite among contractors and building owners in Colorado and around the world. 

A Closer Look at TPO Roofing

TPO is relatively newer product that has risen in popularity in the last twenty years due to it’s energy efficiency, ease of installation with contractors, and cost effectiveness.  Depending on several variables, a TPO roof will often come in at a similar price point then EPDM and looks very similar to the higher priced PVC roof.  However, TPO and PVC are two very different types of materials and PVC has been known to outlast TPO.  The flexible plasticized TPO was first used in the 1970s as a more malleable material to be welded with heat. As you learned in the blog, EPDM is bonded with adhesive and the seams are re-enforced with uncured EPDM seam material. The innovation of TPO is that a contractor could use a hand held heat device to heat the seams and watch as the mold together.  As the material developed it is now common practice to use a robotic heat welder that is pushed by the roofer and welds the seams very effectively making chemical adhesive necessary and arguably has a stronger bond at the seams which is where a flat roof tends to fail. 

The properties of TPO that make it such a popular material for building owners include: 

1. It offers many benefits like those found in EPDM and PVC, and at a competitive cost; 2) The welding process provides better quality assurance because there’s no chance*of compromising seams due to low temperature applications or human error during construction (hot air-weldable). 3), This particular grade has excellent strength ratings so you know your structure will withstand whatever comes its way – even extreme weather patterns. TPO also comes in 45mil, 60mil, and 90mil thickness. It typically comes in white versus EPDM’s black which makes it more reflective of UV rays thereby less heat absorption into the building.  Many roofing contractors favor TPO roofing over EPDM roofing because of the cleanliness that a TPO job has versus an EPDM roof.  EPDM tends to gather dust and the black rubber gets on your hands and clothing whereas TPO does not require chemicals to adhere the seams and does not get on your hands and clothing. It tends to be easier to cut and move around a roof making it easier to install. 

A Closer Look at PVC Roofing

PVC Membrane roofs have a long history that dates back to the early 1960s. They were first used in Germany and by 1970 spread across North America, with PVC membranes now having one of if not longest track records out there for roofing materials today. PVC roofs have been known to last thirty, forty, and even fifty years from installation. They are an excellent material when installed correctly 

PVC is an excellent material for use in fire safety applications. It can resist burning and even trap fuel so it will never go up like a torch! PVC sheets are typically extruded, calendared or made through spread coating with glass fiber mats to reinforced them; they contain stabilizers/plasticizers to allow flexibility without breaking under pressure while containing foam backing which provides sag resistance when needed most. 

When comparing PVC to TPO and EPDM, there are a few factors that need consideration. Nowadays it is not just the initial installation cost which makes them compete in different prices but also how long each type will last before failure occurs and their life cycle costs over time.  With advances occurring recently within both technologies with improvements made possible through adhesive technology ,the gap has narrowed significantly so now and PVC may be considered less expensive when considering all aspects. It can very challenging to a building owner to decide on PVC when the price for TPO and EPDM is often much lower, but often a warranty for a PVC roof is longer than TPO and some companies even offer 50 year warranties on PVC products. 

The Flat Roofing Winner: EPDM

In summary, today’s flat roof systems are time-tested and built to last, which is very much in sync with the growing emphasis on sustainable construction. EPDM, TPO, and PVC have earned a great reputation for weatherability, hail resistance and long-term value from over many years of real world performance. Technological advancements such as seam tapes, primers, robotic heat welding, puncture resistant membrane options, and more robust flashing details have made flat roof systems the system of choice for countless architects, contractors and building owners.

As an experienced roofing contractor and having witnessed the performance of all three materials, we believe the winner of the flat roof materials competition is EPDM.  EPDM has a similar time tested longevity as PVC and at a lower price point.  EPDM materials are readily available in the Colorado market and the labor pool to install this material is greater.

If you want learn to more about flat roofing or are in need of a free commercial roof inspection give us a call today! 720-484-1600