Understanding the Impact of UV Radiation on Industrial Roofing Materials

No matter what commercial building roof type you have—metal, ethylene propylene diene monomer (EPDM), single ply, tar and gravel, foam, TPO, flat or asphalt shingles—the impact of ultraviolet (UV) radiation on roofing materials is significant and can lead to both physical and chemical degradation over time. As such, it’s important to understand how UV radiation impacts each roof type and how to prevent problems from occurring.

The Impact of UV Radiation by Roofing Material Type

Every roofing material is impacted by the sun differently. As such, it’s beneficial to know how UV radiation affects the five most common commercial roof types, so you can be on the lookout for complications and be aware of how your commercial roof may be impacted.

Metal

Metal itself is not degraded by UV rays, but the paint systems and protective coatings (like PVDF or polyester finishes) on top of it can peel, fade, or become damaged over time. “More specifically, UV radiation can cause the resins in metal roofing coatings to chalk or degrade, reducing the roof’s aesthetic appeal and potentially exposing underlying metal, which can rust and corrode,” said Steven Fisher, Brand Manager for Capital Roof Care (CRC). Moreover, UV radiation will heat the metal, leading to thermal expansion and contraction cycles that can loosen fasteners and create gaps at the seams or joints resulting in leaksand an emergency roof repair cost.

Single Ply (EPDM, TPO & PVC)

Although single-ply roof systems are designed with varying levels of UV resistance, these roofs can be negatively impacted by prolonged UV radiation over time. “Similar to metal roofs, single-ply roofs can suffer from surface degradation and brittleness,” said Fisher. “UV radiation on these surfaces also causes a loss of flexibility by breaking down the chemical bonds of the materials, accelerating the aging of seams, sealants, and adhesives, causing shrinkage and dimensional instability and contributing to heat buildup and expansion stress due to loss of reflectivity.” Because EPDM is typically black, this roof type also tends to absorb more solar radiation, increasing surface temperatures and resulting in membrane fatigue and material breakdown.

Polyurethane Foam

Polyurethane foam roofs are highly susceptible to UV damage if not properly protected. Unprotected polyurethane foam roofs can begin to degrade within days of UV ray exposure, resulting in powdering or chalking, surface erosion, and a gradual loss of material thickness over time. “As UV-degraded foam erodes, it becomes porous and water-absorbent, compromising the roof’s waterproofing capability and causing commercial roof leaks,” said Fisher.

Built Up Tar and Gravel Roof & Asphalt Shingles

Gravel and tar roofs are comprised of multiple layers of asphalt, hot tar, and roofing felt with gravel on top. Asphalt shingles are similar in composition but are in a different form—shingles. “The roofing gravel granules are the roof’s first line of defense against UV rays,” said Fisher. “Shingles covered with stronger granules, with a lower rate of separation from the surface aid in resisting long-term exposure of asphalt to harmful sunlight.” If the gravel is removed and the tar is exposed, UV rays can cause cracks to form.

Both tar and gravel roofs and asphalt shingles get damaged when UV rays break down the asphalt binders, resulting in drying and hardening, brittleness and cracking, and a loss of water proofing properties. UV heat also causes the roofing materials to expand and contract, leading to blisters, splits, and delamination of the roof layers.

As you can see, UV radiation can cause many long-term consequences to a commercial roofing system. This also includes a reduced roof lifespan, increased maintenance costs, and decreased energy efficiency of your commercial facility over time when the roof system’s insulation or reflective surfaces are compromised. To prevent these problems from happening, it’s important to be aware of UV radiation mitigation strategies.

UV Radiation Mitigation Strategies

There are a few steps facility managers can take to prevent UV radiation from damaging their commercial roof system. These options include applying commercial roof coatings, installing a cool roof, and conducting regular roof maintenance and inspections.

Types of Roof Coatings

The best thing you can do to protect your roof is to hire a commercial roof coating contractor to apply an industrial roof coating, which will reduce absorbed UV radiation. “American Weatherstar, an industry-leading manufacturer of fluid-applied roof restoration solutions and a trusted partner and supplier of CRC, recommends three commercial roof coating systems,” said Fisher.

Reflective Roof Coatings

The first type of roof coating American Weatherstar recommends to reduce the sun’s impact on roof surfaces is a reflective roof coating. The application of this product will outperform most conventional roofing membranes, such as modified bitumen, EPDM, and built-up roofs. By adding a layer of UV protection to the roof, you can help your facility maintain a cooler interior climate, reduce energy usage, and prolong the service life of the roof by preventing degradation of the existing roof membrane.

Elastomeric Coatings

The second type of roof coating American Weatherstar recommends is elastomeric coatings, which are liquid-applied roofing materials that cure into seamless, flexible, and rubber-like membranes. These coatings can be stretched to at least twice their original size (100% elongation) while returning to their original form without damage or distortion. Elastomeric coatings, which are solvent-based or water-based, can be used to restore a variety of commercial roofing materials including:

Built-up roof (BUR)
Modified bitumen
TPO
PVC
EPDM
Spray polyurethane foam (SPF)
Concrete

Elastomeric coatings work well because they form a thick (approximately 10 times thicker than paint) flexible membrane that is easy to apply and highly adaptable to various atmospheric conditions. These coatings add an extra layer of waterproofing and UV protection to existing roof surfaces, prolonging service life and restoring performance. Most elastomeric coatings can also be tinted in different colors and exhibit excellent long-term color retention. This attribute can help maintain the appearance of roof surfaces and mask signs of superficial damage, aging, rust and corrosion, and general wear and tear.

Solvent-Based Coatings

The two most popular types of solvent-based coatings are silicone and urethane.

Silicone is perhaps the most popular chemistry type in the roof restoration industry. A silicone roof coating provides an excellent solution for restoring and protecting a wide variety of commercial roofing substrates including metal, modified bitumen, single-ply, EPDM, TPO, BURs, concrete roof decks, and SPF.

Silicone roof coatings also offer amazing UV protection, because this coating can reflect up to 80-90% of the sun’s harmful UV rays. Unlike other products, a silicone coating will not degrade, chalk, or crack from prolonged exposure to direct sunlight because this product erodes much slower than other elastomeric coatings without becoming too brittle or hard. When properly applied and maintained, silicone coatings can last anywhere from 10 to 20 years or longer.

Urethane (polyurethane), on the other hand, is among the industry’s most durable and robust types of coatings, even though it is more expensive than other kinds of elastomer. There are two types of urethane elastomeric coatings: aliphatic and aromatic, with each suited for specific coating applications.

Aliphatic urethanes are used as a topcoat because they provide superior UV stability, durability, and possess a low-to-moderate solids content, while holding their color quite well.

Aromatic urethanes have moderate-to-high solids content. They are used primarily as a base coat because they do not hold up well in the sun. Aromatic urethane is more cost-effective than the aliphatic variety.

Water-Based Coatings

Water-based coatings use water as their liquifying agent instead of chemical solvents. These elastomers have a minimal environmental impact and are touted for their sustainable manufacturing practices. Acrylic is the only type of water-based coating suited for the demands of commercial roof restoration.

Known as “the original” elastomeric coating, acrylic is ideal for roofs with adequate drainage—particularly sloped metal roofs. In terms of volume, acrylics are essentially half solid material and half water, with much of the product lost through evaporation during the curing process. As a result, acrylics—despite being cheaper than silicone and urethane—require more product during application.

Installing a Commercial Cool Roof

The second thing you can do to prevent UV radiation on your industrial roof is to install a highly reflective roof, also known as a “cool roof.” Installing this type of roof can help prevent early damage from the sun and may even help reduce cooling costs. According to the U.S. Department of Energy, a highly reflective roof can keep the roof surface 50°F cooler.

A cool roof is designed to reflect more sunlight than a conventional roof by absorbing less solar energy. Almost any type of building can benefit from a cool roof, but you should consider the climate and other factors before deciding which one to install. Many types of cool roof systems are available. Talk to a CRC professional to determine which option would work best for your commercial facility.

Conducting Regular Inspections and Maintenance

The third thing facility managers can do to prevent UV radiation from damaging their commercial roofs is to conduct regular commercial roof inspections and perform routine maintenance. Having your roof inspected at least twice a year for damage through a regular maintenance plan is paramount. “Hire a professional like CRC to perform these inspections, since trained roofing personnel will know what to look for and how to conduct an industrial roof assessment safely,” said Fisher.

A CRC commercial roof assessment will pinpoint small issues that can be corrected before they become a roofing emergency. During each commercial roof inspection, CRC will provide a thorough assessment by checking your entire roof system for:

Loose rivets, bolts, and other components
Seams and cracks that could cause leaks
Low points where water could pool
Signs of movement
Components, such as rooftop units and drainage systems, which might be causing issues
Potentially damaging debris on the roof

If you’re looking for more peace of mind and want to be cost-effective, you should reach out to a CRC professional and ask about a commercial roof maintenance plan.

A commercial roof plays a critical role in protecting a building and everything inside of it—employees, customers, equipment, and inventory—from outdoor contaminants and adverse weather conditions. A good roof also helps ensure year-round energy efficiency and a comfortable working environment. With an understanding of how UV radiation impacts each commercial roof type and how to prevent problems from occurring, you can ensure your facility runs safely and profitably.

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