Tracking Down Roofing Issues

Why Thermal Shock Is More Of A Problem With Asphalt Shingles Than With Metal Roofs

Thermal shock isn't an asphalt-exclusive problem, but it's more likely to cause bigger problems with asphalt roofing than with metal roofing. Here's why.

Why asphalt is vulnerable

Asphalt roofing relies heavily on its elasticity to survive changes in temperature, but the same conditions that cause thermal shock are likely to make it more susceptible to thermal shock. That's because the sun's UV rays can cause damage to the asphalt roof over time that makes the roof surface slightly more brittle. Asphalt is especially great at catching and holding heat, and the darker it is, the more heat it will catch. And the more brittle it is, the less able it is to expand and contract rapidly without buckling or cracking. So the thermal shock damage to an asphalt roof is likely to result in weakening and structural damage to the roofing material itself.

Why metal is less vulnerable

With a metal roof, there's not as much expanding and contracting that has to be done because the roof does not heat up as much in the sun due to its reflectivity. This reflectivity means that, unlike asphalt, it doesn't catch and hold the sun's heat. (This is incidentally also great for your AC energy bills.) In addition, the metal roof does not. The metal roof is designed to be fastened down with special fasteners that hold it tightly enough to be secure but loosely enough to get a little bit of play so that it can expand and contract slightly when it needs to. However, although it's less likely to have severe damage directly caused by thermal shock, a metal roof can become compromised indirectly by thermal shock; the expansion and contraction can make the roof's coating wear away more quickly around the nail holes and even loosen seams between panels, which is one of the reasons it's important to have your metal roof inspected every few years and occasionally re-coated. 

As you can see, a metal roof is less likely to be substantially damaged by thermal shock. When you add this benefit to the already great numbers that prove metal roofing is more affordable over the roof's lifespan than asphalt roofing is, and the numbers that prove how much more eco-friendly metal roofing is and how it can save you money on your AC bills, it becomes obvious that metal roofing could be the best choice for your next roof replacement.

To learn more, contact a business like The Roof Doctor.