All across the country, this summer has proven to be a scorcher. While most property owners know how important it is to keep their visitors and tenants cool, they may not be thinking about the effect the heat on the roof is having on their building. If you are responsible for a commercial property, it is essential to understand the ramifications when the roof is exposed to extreme temperatures. If your roof is black, you only need to walk across the asphalt parking lot to understand just how hot the roof temperature is probably getting. Dark roofing materials absorb up to 90% of the solar energy and convert it to heat, which can be difficult on the roof structure, as well as raise the internal temperature of the building. In contrast, white roofing materials reflect the light and can keep the building cooler.
In order to illustrate the difference, let’s assume it is a 90-degree, sunny Southern day. The surface temperature on a black commercial roof can rise to 140 degrees and can even get as hot as 190 degrees. However, a white roof on the same day will typically register between 102 and 120 degrees, a significant difference. The rooftop temperature is influenced by two different properties:
- Solar reflectance: the material’s ability to reflect the sun’s energy back into the atmosphere
- Thermal emittance: the amount of heat the material rejects instead of absorbs
Why Does Roof Temperature Matter?
Obviously, the temperature on black roofs is the most extreme. While commercial roofs are designed to last 20 years or longer, the lifespan of black roofs may be shortened as heat can accelerate the breakdown of materials. In fact, the wear and tear that heat causes is the main challenge when it comes to black roofing longevity. The older the roof gets, the more pronounced the problems become.
White roofs can be 50 or more degrees cooler than black roofs, and coated roofs are also significantly cooler, which has a profound effect on the temperature inside the building. Simply put, a hotter roof makes for a hotter interior, as heat absorbed into the roof surface can radiate that heat inside. inside, especially in buildings with older roofs that were not assembled using R20 and R30 insulation. Newer insulations such as R20 and R30 are more effective at blocking heat than products from even just a few years ago – but many area roofs predate these more effective options.
Did You Know? Adding a white or light-colored coating can reduce heat radiation enough to resize your AC, lower energy costs, and reduce the demands on the power grid. The Green Building Alliance reports that cool roofing may result in energy savings ranging from 7%-15% of your total cooling costs. It is important to point out that in order to enjoy the greatest benefit of a coated roof, it should be routinely cleaned, inspected, and repainted every 10-15 years.
Is Coating An Option for Your Roof?
While you cannot control the weather, you do have some control over how hot the roof temperature becomes in the summer. New coating technologies not only help with cooling and energy costs, but they can help to protect the roofing material and extend the lifespan of your roof for decades.
If your roof is getting older, is in need of repair, or simply generates too much heat in the summer – roof coating may be an excellent option. When you are ready to learn more, call Unicoat Industrial Roofing for an assessment. Don’t install a new roof before talking to our experts – we may be able to provide a lower-cost solution for your property.