Commercial Roofing Systems: How They Compare

Thermoplastic Polyolefin—better known as TPO—is a single-ply roofing membrane. TPO roofing is a popular substrate for commercial and industrial buildings. It’s is made up of a single layer of synthetics and reinforced scrim. TPO is categorized as “single-ply” meaning it’s installed to roof surfaces in one layer unlike alternative multi-layer roofing systems.

Pros

TPO is manufactured in white, which offers great UV reflectivity. TPO is also a relatively inexpensive commercial roofing system as contractors have the ability to install the roof faster than any other type of commercial roof membrane—ultimately cutting labor expenses. The membrane is also inexpensive to manufacture, which cuts expenses even more.

Cons

As with any new technology, TPO had quality issues in the early stages of its formulas. Manufacturers overcame this issue in later formulas, and TPO now has much more longevity. While we have found that the 45-mil thickness TPO isn’t strong enough to last for the duration of the warranty, the 60-mil and 90-mil thicknesses typically last longer.

Life Expectancy

TPO roof systems last anywhere from 10–25 years depending on the quality of application and mil thickness. It is commonly manufactured in 45-mil, 60-mil, and 80-mil thicknesses.

Installation Process

Commercial TPO membrane is commonly manufactured in 4, 6, 10, and 12 ft. rolled sheets. The rolls must be placed on rooftops using a boom truck or crane, and the membrane is either fastened to the roof with screws or glued to the insulation board. They are welded together—usually with a robotic heat welder—to create a watertight seam.

Video: Click here to watch a detailed overview of a TPO roof installation.

Approximate Cost

$3.00–$9.00 per sq. ft.

Polyvinyl Chloride—better known as PVC—is another type of single-ply. It is a thermoplastic material installed on commercial buildings. PVC is a generation older than TPO and does not have the market share that TPO enjoys.

Pros

The high-quality PVC commercial membranes on the market today are very flexible and have remained that way for many years. Typically, restoration systems applied on commercial roofs with PVC membrane last longer than those applied on roofs with TPO. Like TPO, PVC membrane is white and offers great reflectivity to the sun.

Cons

As with all single-ply membranes, thinner PVC materials do not last as long as the thicker versions. The cost of PVC is a potential limitation as well. PVC roofing is more expensive than TPO because of its longer installation process and higher manufacturing cost.

Life Expectancy

A PVC commercial roof typically lasts 15–30 years depending on thickness and quality of the installation.

Installation Process

Similar to TPO, PVC is a heat-welded single-ply material. Since the rolls are six feet rather than ten, PVC’s installation process usually takes longer. The welding of PVC is also not quite as fast.

Approximate Cost

$5.00–$12.00 per sq. ft.

Ethylene Propylene Diene Terpolymer—better known as EPDM—is the last but certainly not the least of the single-ply membranes covered so far. EPDM roofing is the original single-ply membrane technology.  Unlike TPO and PVC, EPDM is typically black, which makes it a great solution for northern climates in which heat-absorbing roofs are beneficial. EPDM is formulated in 45-mil and 60-mil thicknesses.

Pros

When it comes to single-ply roofing, the flexibility of EPDM is unmatched. Because this type of commercial roofing material is produced by companies such as Firestone, it is made with a chemical make-up similar to automobile tires. At American WeatherStar, we have restored millions of 25-year-old EPDM roofs that still had life left in them—this type of rubber membrane is very durable.

Cons

Most EPDM is black in color. This brings an incredible heat load to buildings which is a negative for warm climates. White is available but is seldom used in EPDM roofing applications. Another concern is that the seams in EPDM membranes are prone to fail, as they are not as strong as the heat-welded seams that TPO and PVC offer.

Life Expectancy

EPDM commercial roofing systems can last up to 30 years if the installation is done correctly, and the correct mil thickness is chosen. If there is mechanical equipment on the roof, it is essential to use the thicker EPDM material, as it is more durable to foot traffic and tools.

Installation Process

EPDM is manufactured in as small as 6 feet to a roll and as large as 50 feet to a roll. Obviously, the 50 ft. rolls are used in very large projects and a crane is used to hoist them to the roof. The most common EPDM membrane size is 10 ft. x 100 ft.

There are two methods of sealing the seams for EPDM. They are either adhered with a specially designed glue, or a peel and stick EPDM tape is installed at the seam to ensure a watertight membrane.

Approximate Cost

$4.00–$10.00 per sq. ft.

Built-up roofing—often referred to as BUR—is the oldest type of commercial roofing system on the market today. As its name describes, BUR is created by building up layers of asphalt roofing material. A typical “4-ply” commercial roof is four layers of felt sandwiched between layers of hot asphalt.

Pros

A life expectancy of up to 50 years is certainly BUR’s greatest advantage. Built-up roofs are also very strong, durable, and can handle any type of climate and foot traffic.

Cons

Because of its asphalt foundation, a built-up roof does not have a great deal of flexibility. Asphalt and the sun’s UV rays do not mix well. The exposed asphalt will dry out and crack, causing premature degradation.

Life Expectancy

BUR can last up to 50 years if installed properly and maintained.

Installation Process

While a BUR is a great commercial roofing membrane, it is rarely installed these days as safety and efficiency have caused it to become outdated. Built-up roofs are applied by using a kettle to heat the asphalt to over 400°F, which is then “mopped” onto the roof by commercial roofers. This practice is not safe or efficient, but it was the only option for roofers of the past.

Approximate Cost

$6.00–$14.00 per sq. ft.

Modified Bitumen—normally referred to as mod bit—is an asphalt membrane with plastic and rubber polymers added. Mod bit commercial roofing membranes were the first evolution away from the traditional built-up roofs of generations before This type of commercial roofing material comes in either a smooth surface or a granulated top layer, adding UV resistance and durability for foot traffic.

Pros

Mod bit is one of the strongest commercial roof systems on the market today. It lasts longer and is easier to restore than most other roof types. The durability of a mod bit roof is outstanding. Service technicians accessing mod bit roofs rarely cause any damage.

Cons

The cost of mod bit roofs is their biggest drawback. These roofs take longer to install, and the rolls are expensive to manufacture.

Life Expectancy

Modified bitumen typically lasts at least 20 years so long as it is installed properly.

Installation Process

Mod bit comes in 3 ft. x 100 ft. rolls. Mod bit must be hoisted to the roof with heavy equipment. Each roll is installed using one of three methods: torch-applied, hot-mopped, or cold adhesive. In some cases, two layers of mod bit commercial membrane are installed to increase the warranty term.

Approximate Cost

$5.00–$12.00 per sq. ft.

There are many different types of commercial metal roof panels, but the two most common are a standing seam metal roof and an R-panel metal roof. The primary visible difference being that a standing seam roof has a much taller rib, and the fasteners are hidden. Standing seam metal roofs are commonly found on high-end buildings such as schools and churches. R-panels are much more common in the market and are found on just about any type of commercial building.

Pros

The low cost of an R-panel metal roof is one of its strongest benefits. A metal building is overall less expensive than other types of construction, which is why metal roofs are one of the most common types of roofs on the market today. A standing seam metal roof is more expensive, but it also lasts longer due to not having exposed fasteners.

Cons

The primary negative to a standing seam metal roof is the cost. Though much less expensive, the primary weaknesses in an R-panel metal roofs are the exposed fasteners. The thermal movement of a metal roof in warm climates is excessive, which causes the fasteners to be loosened over time.

Life Expectancy

Typically, metal roof systems last 25–50 years, depending on the gauge of the material and quality of the installation.

Installation Process

Panels are lifted to the roof and fastened to iron purlins that make up the roof deck. The panels overlap one another in order to keep water out.

Approximate Cost

R-Panel: $3.00 – $6.00 per sq. ft.; Standing Seam: $6.00 – $15.00 per sq. ft.

Spray polyurethane foam—commonly referred to as SPF—is a plural component spray-applied roofing system. SPF commercial roofing is almost exclusively used to restore existing commercial roofs or add insulation to a building. SPF must be top-coated with a UV-resistant elastomeric roof coating to protect the foam membrane from the sun.

Pros

The greatest attribute of SPF roofs is their insulation. Not only do SPF roofs have a great R-value of any commercial roofing materials, but SPF acts as an air barrier.

Cons

The primary drawback to SPF is its lack of durability. Mechanical contractors accessing a roof often damage the foam. If an SPF roof is not maintained and repaired, these small problems become a larger issue over time.

Life Expectancy

The lifespan of SPF is dependent on the quality of the application. If installed properly, an SPF commercial roof can last anywhere from 20–40 years, depending on the application thickness of the elastomeric coating. If maintained and recoated every 10–15 years, an SPF roof can last much longer.

Installation Process

SPF commercial roofs are only installed using plural component equipment that is specially designed for spraying polyurethane foam. A minimum of 1-inch of spray foam is applied to the entire roof surface and around penetrations to create a seamless and fully adhered roofing membrane.

Typically, the raw chemicals that comprise SPF remain on the ground in drums and are pumped onto the roof during the application process. Silicone is the most common coating applied to SPF commercial roofing, as it is the best material for UV stability.

Approximate Cost

$5.00–$8.00 per sq. ft.

The commercial roof coatings industry began to take shape in the early 1970s. The first elastomeric coatings were used on metal roofs to provide a flexible, bright-white, protective finish to slow down the expansion and contraction of metal roofs and prevent the spread of rust and corrosion.

The roof coatings industry is one of the fastest-growing segments of the commercial roofing industry. Fluid-applied systems, as they are often called today, are used to restore each roof type described above. These systems are installed at 20 to 40 mils, depending on the warranty term required.

American WeatherStar’s Ure-A-Sil flat roof restoration system is our flagship solution for EPDM, PVC, TPO, mod bit, BUR, and SPF roofs. The Met-A-Gard, Met-A-Gard+, and Met-A-Sil metal roof restoration systems are designed to restore both R-panel and standing seam metal roofs.

Pros

With commercial roof coating systems, building owners get to keep their current roof—there is no tear-off involved. A fluid-applied system is designed to make an existing roof last longer, and they typically cost much less than a full roof replacement.

Cons

The application window for roof coatings is shorter than other types of commercial roofs. Roofing contractors must be cautious of dry time, rain, and freezing temperatures. Very few roof coating applications happen in the northern climates during the winter.

Life Expectancy

A fluid-applied commercial roof restoration system can last 10–20 years depending on the quality of installation and the mil thickness used in the system.

Installation Process

Like an SPF system, roof coating materials come in drums or pails. They can either be spray-applied or rolled using industrial spreaders and rollers.

First, the roof is cleaned and primed—if necessary. All seams, fasteners, and penetrations are then coated with a viscous material known as waterproofing mastic. To complete the system, multiple coats of elastomeric roof coatings (e.g., acrylic, silicone, urethane, etc.) are applied.

Approximate Cost

$2.00–$5.00 per sq. ft.