When most of us picture a roof, we imagine rows of shingles spread across a steeply sloped roof, from the gutter’s edge, all the way to the peak. But look around, and you’ll see flat or barely sloped roofs on many commercial buildings, warehouses, schools, and even some of the more modern homes in Traverse City. These buildings with low-sloped or flat roofs are being protected by a single layer of membrane rather than individual shingles or sheets of metal.
When it comes to protective membranes for flat roofs, the two most popular options are TPO and EPDM roofing. Both of these flexible, rubber-like membranes are widely used; each has distinct characteristics that make it suitable for different situations. In this guide, readers will explore both of these roofing systems, learning about their history, how they are made, where they perform best, and the advantages and disadvantages of each. For homeowners and building owners considering TPO or EPDM for their property, and for those who are just curious, get ready to gain a better understanding of these two materials. To begin, let’s learn why flat roofs need these specialized materials in the first place.
Why Flat Roofs Require Specialized Materials
Unlike sloped roofs, which quickly shed water and snow with gravity, flat roofs have to drain water much more slowly. Flat and low-sloped roofs are not perfectly level; they have gradual slopes that direct water to drainage areas, but they still hold moisture much longer than a sloped shingle or metal roof. Because of their design, traditional asphalt shingles and metal roofing do not work well for flat roofs. Instead, buildings with flat or low-sloped roofs are covered with a waterproof membrane to create a protective surface.
Enter TPO and EPDM roofing. These are the two most commonly used membranes due to their flexibility, durability, water resistance, and ability to protect buildings for decades. Now, let’s get into the details of each, everything from history and development to how it’s made and the applications for both. You’ll also discover the unique advantages and disadvantages of both roofing systems.
The History and Development
EPDM
Standing for ethylene propylene diene monomer, EPDM roofing is a synthetically made rubber membrane used for flat or low-sloped roofs. EPDM roofs have been around for decades, first used in the 1960s for the automotive industry, and have since become widely popular for roofing. With over 50 years of use in roofing systems, EPDM is one of the most proven roofing membranes. Manufactured from synthetic rubber and natural gas, EPDM membranes also contain oils, fillers, curing agents, and stabilizers. Manufactured in large sheets, EPDM comes in black, white, and gray and is available in a range of widths and three thicknesses.
TPO
Standing for thermoplastic polyolefin, TPO is a newer material introduced in the early 1990s. Like EPDM, TPO is a single-ply membrane, but instead of being made from rubber and natural gas, it is made from a blend of polypropylene and rubber. Like EPDM, TPO is also made from a combination of other materials, including fillers, UV stabilizers, and fire retardants. Compared to other roofing materials, TPO is considered a newer option. Even so, today’s products have advanced significantly from the earliest versions and have become the most popular flat roof covering in North America.
How They Are Installed
EPDM
EPDM roofs can be installed in several ways. Adhesives, mechanical fasteners, and ballast systems may be used, and unlike TPO, seams on EPDM roofs are typically joined with specialized tape and adhesives rather than heat welding.
TPO
Like EPDM roofs, TPO roofs can be installed using several methods. There are fully adhered systems, mechanically fastened ones, and, although less common today, some are installed using ballasted systems. As mentioned above, a defining characteristic of TPO roofs is the use of heat-welded seams, which are stronger than the membrane itself.
The Advantages
EPDM
- Proven longevity with many installations lasting more than 30 years with proper care and maintenance.
- Extremely flexible, even in cold temperatures.
- Superior weather resistance, protecting against snow, ice, hail, wind, UV radiation, and ozone.
- Proven track record, over 60 years of data.
- Easy repairs with compatible patching materials.
- Puncture-resistant.
- Lower cost compared to other materials, besides TPO
- Recyclable
TPO
- Durable, strong, lightweight (lighter than EPDM), yet puncture-resistant material with exceptional UV resistance.
- Enhanced energy efficiency with its bright white surface, which reflects light rather than absorbing it, reducing cooling costs during warmer months.
- Heat-welded seams create superior waterproofing.
- Resistant to chemicals like grease, oils, and airborne contaminants, making it popular for commercial buildings.
- Lower cost than EPDM
- Recyclable
The Disadvantages
EPDM
- The darker color absorbs heat, increasing cooling costs in warmer months.
- Seams are glued, which can require more inspections and maintenance.
- Easily punctured by sharp objects.
- If the material is not properly formulated and manufactured, it can shrink over time.
- The aesthetics may not appeal to every property owner.
TPO
- The membrane quality can vary by manufacturer.
- Less long-term performance data than the more proven EPDM membrane.
- It can become brittle, leading to a shorter lifespan.
- Performance depends heavily on installation quality.
- Requires specialized welding equipment.
TPO vs. EPDM: Key Differences That Set Them Apart
It’s clear to see why these two roofing membranes compete for the same projects. The key differences that set them apart from each other and may lead a roofing company in Traverse City to pick one material over the other include:
Durability and Longevity: In climates with harsh winters, like ours in Traverse City, EPDM generally has a longer lifespan. Remaining flexible even in cold temperatures, it has earned a good reputation in northern climates.
Energy Efficiency: Due to TPO’s reflective surface, it stands out as the most energy-efficient material, although lighter colored EPDM products are now available.
Installation Method: Using heat-welded seams, TPO membranes have stronger seams than the traditional glued-on method.
Maintenance: Both products will require occasional inspections, cleaning, flashing checks, and repairs; neither will be “maintenance-free.”
What Buildings Commonly Use TPO or EPDM?
These roofing systems are used on buildings with flat roofs or low slopes. Most commonly, flat roofs are seen on:
- Office buildings
- Retail stores/Shopping Centers
- Warehouses
- Schools
- Hospitals/Medical Facilities
- Apartment Complexes
- Industrial buildings
- Churches
- Some residential homes.
As waterproof barriers, both materials effectively protect flatter roofs from water intrusion. Ultimately, the choice is up to the property owner and the roofing company.
Getting to the Bottom of It All
Both TPO and EPDM have earned their place among the most popular membranes used for flat roofs. Sharing the same purpose, they both have unique properties and characteristics that make them more appropriate for a project than another. Based on roof size, building use, energy goals, budget, and local climate, a qualified roofing company can help evaluate which material fits your specific needs. TPO offers energy efficiency and heat-welded seams, where EPDM brings decades of proven durability, flexibility, and reliable performance in cold climates.
So, instead of asking which one is “better,” it’s most helpful to understand where each one excels. Both TPO and EPDM are fantastic options when properly installed. If you have a flat roof and it’s time to replace the membrane, knowing the strengths and limitations of both TPO and EPDM membranes can help you make the best decision for long-term protection and peace of mind.