Dispelling Myths About Radiant Barrier Systems
Despite the fact that radiant barrier has been around for more than a quarter of a century, and it has been proven effective by hundreds of research trials and onsite testing, there are still misconceptions about how radiant barriers work. Consumers have even questioned whether or not reflecting the heat out through the roof can negatively affect the roof shingles.
First of all, radiant barriers are part of a “system,” a cooling/heating strategy. The basic product is a type of aluminum foil – much enhanced from your typical kitchen foil. This material is stapled to the underside of the top chord of the roof trusses or to the underside of the roof decking so that there will be an airspace below it to the attic floor. The radiant barrier blocks the radiant heat transfer between a surface that is giving off heat, such as a hot roof, and a surface that can absorb this heat, like conventional attic insulation.
Without a radiant barrier to block the heat coming into the attic through the roof, the heat gets radiated to the insulation which transfers it to the material it touches, primarily your home’s ceiling. Now you’ve got a hotter house, making you uncomfortable and causing the air conditioner to run longer to get rid of the heat.
Research has found that a radiant barrier system can block up to 97% of the heat that gets radiated downward by the roof before it gets to the insulation.
Even if your attic is well-ventilated, temperatures in a typical attic on a hot summer day can easily reach or exceed 150 degrees F. That’s why you need to get this heat out of the attic before it gets into your living space.
As for its effects on roofing material, it is pretty unlikely that radiant barrier systems can cause any damage to roof shingles even on the hottest days. Roofing materials are obviously made to withstand very high temperatures, and research has found that a radiant barrier only increases their peak temperatures by five degrees or less – not very significant when you consider that peak temperatures on the shingles can easily reach 160 to 190 degrees without causing any damage.