Everything to Know About TPO
Since its introduction in the 1990s, TPO has become the most popular type of commercial roof available. Contractors install approximately one billion square feet of this product annually. According to the industry experts at GAF, it makes up more than 50% of single-ply roofs installed today.
TPO is a reliable, low-slope roofing system that has offered excellent performance at a low cost to Northern California businesses for the past 20 years. TPO is a durable, versatile, and cost-effective solution for new roofs and re-roofing projects, and with minimal maintenance requirements, TPO might be the right choice for your facility. Because the exposed surface is a reflective white, TPO is especially suitable for hotter, sunnier climates. White thermoplastic reduces cooling costs and saves energy in warmer temperatures.
If you are a business owner or property manager and think you need a new roof, TPO roofing might be the best option.
To find out more about what brand, thickness, and attachment process we recommend, talk to our professional commercial roofing contractors.
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What is TPO?
TPO, which stands for thermoplastic polyolefin, has been used in roofing since 1989. Thermoplastic Polyolefins (TPOs) materials, initially used for pond liners, are polypropylenes that manufacturers altered to improve ductility and impact resistance compared to standard polypropylene. Ductility is the degree to which a material can maintain shape under tensile stress, so maximizing ductility has allowed TPO to be rolled out into strong, flexible sheets that don’t crack.
TPO formulas are continually evolving and improving. Manufacturers have been seeking the best formulas for a specific roofing application. Their goal was to improve TPO’s stability and optimize the balance between material stiffness and impact resistance. Polypropylene and ethylene-propylene rubber combine to create a single layer membrane that roofers attach to a roof either mechanically or with adhesive.
Sutter Hospital, Novato, has a brand new TPO roof installed by ACS (12/20)
Why Choose TPO?
Five Reasons Commercial TPO Roofing Systems Are Popular
- Affordable – Most affordable roofing option with the lowest labor costs
- Adaptable – A premier roofing solution that works for a wide range of building styles
- Easy – Offers easy installation with wide, lightweight sheets and fewer seams (which results in fewer leaks)
- Fast – Installs faster than other roofing systems with lower labor costs
- Long-Lasting – Can last up to 25 years
Business owners and property managers choose Thermoplastic Polyolefin (TPO) because the single-ply roofing membranes offer many performance and installation advantages for their commercial properties.
The reflective white top TPO layer is UV and heat-reflective, which saves building owners money. Their broad, lightweight sheets save time and labor costs on installation. Fewer seams mean fewer places to leak and higher ductility makes it resistant to mold, punctures and tearing. It also helps TPO accommodate movement that occurs as a building settles.
Because TPO is made of 100% recyclable material, these roofs shouldn’t end up in a landfill. TPO roofing systems can last up to 25 years, depending on the climate, quality of the materials used, and the roofing contractor’s expertise.
Choose our certified roofing professional to install your new TPO roofing system. A roofing material is only as good as the roofer who installs it.
Two of the most common and expensive mistakes made by inexperienced TPO installers are improper welding and poor roof tie-ins. Licensed and certified commercial roofing contractors know proper welding techniques and use the best options to tie new roofing to old ones. ACS has over 20 years’ experience in commercial roofing. We will make sure to install your roof correctly.
The distinct advantages of TPO roofing solutions are undeniable (see below). If you aren’t sure if this is the best option for your business or building, reach out to our team. Our experienced commercial roofing contractor professionals can evaluate your situation and present you with the best alternatives for your individual needs.
Ready for your FREE TPO estimate now?
Don’t Delay. Call Us Today! (925) 548-9748
Affordability – It is one of the most cost-effective roofing materials available. Its easy installation lowers labor costs. TPO is one of the least expensive roofing materials available on the commercial construction market, costing far less than other rubber roofing options like EPDM (a type of synthetic rubber).
How much does commercial TPO roofing systems cost?
There are many variables, so prices vary, but a new TPO roof replacement typically costs between $7 and $13 per square foot. Since commercial roofing contractors quote by squares (100 square foot sections), you might see quotes of between $700 and $1,300 per square, including labor.
Strong and flexible – Its UV resistant material resists punctures and tearing, mechanical shearing, and mother nature’s worst. Professionally installed heat-welded seams provide tough and lasting leak protection.
Cleaning – Cleaning a roof less often saves money on upkeep, and the roof lasts longer. TPO is less likely to get mildew or algae growth and doesn’t require pressure washing or biocides. It can be cleaned using Simply Green, an effective, environmentally responsible roof cleaner. TPO membrane is a smooth roof surface, making it more efficient at resisting dirt and debris build-up.
Coating Compatibility – It is compatible with silicone and acrylic roof restoration systems that can significantly prolong its lifespan. Experts recommend waiting until the roof is five years old before adding coating because it may not adhere to the smooth surface of a new TPO roof.
Energy Efficiency – White TPO is very energy efficient. White TPO often exceeds the U.S. Environmental Protection Agency’s ENERGY STAR specifications. Because it reflects harsh sun rays instead of absorbing them, you spend less money keeping your facility cool during hot summer months.
Lifetime Energy Savings– A TPO roofing system can last between 15 and 30 years. It significantly outperforms a gravel or granule coated roof which might be less expensive at install, but have higher energy costs over the life of the roof.
Environmentally Friendly – These “cool roofs” earn LEED points from the Green Building Council and potentially qualify for regional tax credits. Their highly reflective surfaces keep energy costs low during hot summers. TPO helps lower carbon emissions. Additionally, TPO material is 100% recyclable, so ideally it won’t ever end up in a landfill.
Urban Heat Island Effect – Large amounts of black asphalt absorb heat making urban or metropolitan areas several degrees hotter than surrounding suburban and rural areas. TPO cool roofs combat the effect by reducing rooftop temperatures.
Low Roof Load – Because the material weighs so little, the TPO roof load runs about 0.38 lb. per square foot at the 50-mil thickness. Adding insulation will only increase the load to about 1 lb. per square foot. By comparison, asphalt shingles have a 2.5 lbs. load and asbestos-cement shingles, 4 lbs. Depending on the type of material, a 2500 square foot roof could be 1750 lbs. or 50,000 lbs. Why does it matter? The lighter the roofing material, the more load capacity is available for extra weight coming from HVAC units, rain and snow.
Easier Installation – Roofing professionals can install TPO faster and easier than traditional roofing using one of three possible attachment systems. Because TPO can be attached to the roof deck mechanically, with adhesives, or using a ballast system, roofers can use it for various situations and project types. Its flexibility allows it to be heat-welded around chimneys, skylights, pipes, and other roof protrusions.
Exceptional Warranty – A roofing material warranty provides protection for defects in actual roofing materials that disintegrate or break down before they should. Despite being a low-cost solution, TPO membrane roofing systems can come with a 20-year material warranty.
Thermoplastic Polyolefins (TPO) have two other advantages over standard polypropylenes:
- Improved HDT – The Heat Deflection Temperature (HDT), the temperature at which a plastic deforms under a specified weight, dictates how a type of plastic can be used. The right choice of minerals allows TPO compounds to improve HDT. In fact, TPOs retain ductility even in subzero temperatures. Traditional polypropylenes cannot withstand such extremes.
- Faster and Cheaper – Production is quicker and cheaper because TPO’s don’t need to be dried before molding like other plastics. Speed reduces production costs making TPO makes it a popular choice for flat and low-slope roofs.
It’s still a relatively new product – TPO entered the market in the 1990s. Formulas for TPO have continued to evolve and improve, and manufacturers are still working out the ideal formulations. Older materials may not be compatible with more recent formulations.
Will future TPO materials be compatible with older TPO roofs?
Formulas have changed dramatically since the first TPO membranes hit the market. While the earlier materials were very inconsistent, consistency and compatibility have improved. It is possible that future TPO material may not be weldable to old, however, there are peel and stick TPO patches that can address this issue. Some manufacturers offer more consistent compatibility than others, which is why we prefer GAF TPO, given its highest standards of quality and consistency.
Variability in manufacturing quality – Manufacturers sell thickness as strength. Thickness doesn’t guarantee durability if the material is non-uniform. To avoid inconsistent and unreliable material quality, installers rely on the industry brand names, such as GAF, known for their consistency.
This TPO roof failed due to chemical exposure.
Chemical Resistance – It has a low resistance to animal grease, acids, and airplane fuel, so shouldn’t be installed on restaurants or in areas where airplane fuel can lead to degradation.
Puncture Resistance Limitations– While flexible TPO resists punctures, it won’t withstand tree limbs falling on it. If you need to worry about flying debris and falling trees, our professionals might recommend FiberTite, because it’s thin but reinforced with fiberglass to increase puncture resistance. TPO doesn’t go around 90-degree angles as well as PVC, so for flashings and around ducts in the roof, PVC might work better.
Our Conclusion?– We recommend TPO Roofing Systems. The benefits far outweigh the limitations. As professional commercial roofing contractors, we are confident in offering these roofing systems to commercial building owners and property managers.
We installed this 66,000 sq ft Firestone TPO roof for a skilled nursing facility in Novato. See more installations »
The Elements of TPO Roofing
Our professionals will take many factors into account when designing the best TPO Roofing Plan for your building. There are a variety of brands and styles to consider, not to mention the choices for thicknesses. We need to decide how best to attach the membrane and seal the seams. What roofing is there now, and will installers need to remove it? What underlayment does the building’s roof have, and does it need to be replaced? What TPO works best for that underlayment. What kind of foot traffic does the roof have? What works best for the climate.
Overall, a thicker membrane is better. White thermoplastic membrane thicknesses range from 45 mils to 80 mils. The thicker membranes cost more, provide a denser shield to block UV rays, and last longer. When you opt for a higher Mil membrane, you invest in your building. Deciding on thickness is more complicated, however!
While thickness matters, the quality of the material matters, too. Many TPOs roofing membranes contain a reinforced area somewhere in the membrane’s construction, and that reinforced layer has some material above it and some below it. The reinforcement is usually an interlaced matrix of tiny threads called a scrim—the more threads in the scrim, the stronger the support.
Above the Scrim – A membrane is made thicker by adding material above and below the scrim. The wearing surface refers to the top layer of TPO above the scrim. It wears away over time due to foot traffic, severe weather, and the product’s natural aging process. The thicker the wearing surface, the more protected your roof is over a more extended period. The quality of the wearing surface also matters and differs between makers. Once the top layer wears away, and the scrim is exposed, problems start. Manufacturers differ concerning where they place the reinforcement within their membranes.
The term “thickness over scrim” identifies the amount of membrane material above the reinforcement. Here are a few examples of how the same thickness from different manufacturers provides different amounts of the material above the scrim:
- 45-mil-thick membranes, manufacturers’ thicknesses over scrim range from 15 to 19mils
- 60-mil-thick membranes, thicknesses over scrim range from 21 to 27mils
- 72-mil-thick TPO membranes, manufacturers’ thicknesses over scrim range from 26 to 30 mils
The conclusion? Overall thickness matters, but the material’s thickness and quality above the scrim also matter.
There are three methods of installing TPO roofing. Each has advantages and disadvantages.
Mechanical – The installer uses a screw-type fastener to attach the membrane through insulation or cover boards to the decking. The type of substrate will determine which of the many available fasteners will work best. TPO membrane comes in sheets, and they overlap to cover the fasteners. The seam is then welded outside of these fasteners.
Mechanical attachment costs the least and can be done in low temperatures since there are no adhesives. A disadvantage is that the roofs are ONLY attached at the seams, which means the membrane between the seams is loose. Strong winds can cause the membrane to billow up, creating air pockets above the insulation, allowing conditioned building air into this space.
Full adhesion – A roofing professional adheres to the membrane by applying adhesive to both the membrane and the substrate or base. The specially formulated adhesive chemical bonds with the TPO. The substrate under the membrane can be a cover board or the top layer of insulation.
Fully adhered systems cost more but offer several advantages over mechanical attachment. Because the system fully bonds to the substrate, billowing doesn’t happen. Without air pockets, condensation under the membrane is unlikely, and the roof is more energy efficient.
Other than cost, the primary disadvantage concerns seasonal installation. Temperature limitation on the adhesives dictates when roofers can install during the winter.
Ballasted – Installers lay the TPO membrane over the roof and carefully seal around the perimeter and at all penetrations. Ballast is then put on top of the membrane to keep it in place. Smooth, rounded river rocks about 2 or 3 inches in diameter typically serve as ballast, but concrete pavers can also be used. There are benefits to Ballasted installation.
Roofs can be decorative, green, and weather resistant. Ballast materials are non-combustible. Installation is fast and inexpensive, and there are fewer seams. Contractors can use broader TPO panels, which speeds installation and reduces the number of seams. With ballasted installation, solar panels can be added.
On the downside, roof repairs are more complicated, and the roof is heavier. Dirt can build up, and ballast materials with sharp corners may cause damage.
Seams Matter, Too
TPO roofing membrane comes in rolls of various widths. Roofing contractors must overlap the widths and create seams to connect widths every six to eight feet. They then glue, tape, or heat weld the seams. The most vulnerable part of a roofing system is the seams. As materials expand and contract with temperature changes, the seams can weaken and allow water seepage.
An important consideration when choosing a membrane type and thickness is what will be under the roofing membrane. What’s underneath directly impacts how well the membrane performs. If you have a soft fiberboard that gives easily, hail could penetrate the membrane. An underlayment with less give, like hard insulation, permits less penetration, and you might be able to get away with a thinner membrane.
Which TPO Brands Perform Best?
When there are so many claims about TPO, how do I choose the best brand? GAF engaged Structural Research Inc. (SRI), a well-known and highly respected laboratory, to perform the most extensive independent performance study of four major U.S. TPO brands.
Each brand performed similarly in tests for thickness above the scrim and weld strength. Where membranes differed most was in heat-aging, weathering, and weight-loss trials. Results from these three tests are more accurate indicators of long-term membrane performance.
Accelerated weathering tests how long a TPO membrane will last. GAF and Firestone were the two top-performing brands when subjected to accelerated weathering.
- The GAF study found that their EverGuard Extreme 60 mils and 50 mils performed best, showing no visible failures for more than 190 days.
- GAF’s EverGuard TPO and Firestone TPO came in second place. The GAF failed at 112 days, and the Firestone at 105.
- In third place was Carlisle, which failed at 77 days, and Johns Manville, failing at 70 days.
Weight loss in each product was also measured during the accelerated weathering test. Weight loss matters because it leads to membrane breakdown and failure. When membranes lost 1.5% of their weight, they were considered a failure.
- In the weight loss test, GAF EverGuard Extreme 50 and 60 mils didn’t fail under the accelerated weathering conditions until after lasting more than 190 days.
- GAF EverGuard TPO failed at 125 days and Firestone TPO at 136 days.
Consistency – Another observation made in the study concerned product consistency. While you would imagine that the same product produced by the same manufacturer would be consistent in thickness and quality, it turns out that sometimes differences are substantial. The brands that showed the most consistency were:
Can TPO Be Installed Over an Existing Roof System?
TPO Roofing is not the cure-all for all roof problems. Professional roofing practices still apply. Roof layers below the TPO membrane could include:
- Roof deck as the base could be wood sheathing, steel, concrete, gypsum, cementitious wood fiber, Thermoset, or a composite of concrete, steel, and foam boards.
- Underlayment on top of the deck- The underlayment, often a 5/8″ gypsum board, might be installed to improve fire-resistance or create a more solid substrate on top of some deck types.
- Vapor barrier on top of the underlayment – A vapor barrier can be loose or adhered. Something as simple as a 6-mil plastic sheet, a vapor barrier is relatively inexpensive. The barrier protects the insulation.
- Insulation – TPO membrane manufacturers also make insulation. They may require the contractor to use their brand to satisfy the warranty.
- Cover Board – Cover boards provide additional backing above the insulation to improve puncture resistance and extend the roof life. Commercial roofing contractors strongly recommend cover boards on roofs where frequent foot traffic or maintenance occurs.
Removing or replacing old roofing materials will depend on the materials and their condition. Any wet insulation in the existing roof system should be removed. You should not leave old rubber in place because it will cause sweating under the membrane. Removing tar is best despite the cost because you could discover fixable problems under the tar.
If existing insulation and decking passes inspection, a roofing contractor can install a TPO system after applying an insulation board.
The most popular trend in commercial roofing is TPO.
GAF and Firestone were the two top-performing brands when subjected to accelerated weathering tests.