This is a very common myth (intentional scare tactic) used by competing product suppliers. The answer to this question is NO, a radiant barrier will NOT cook your shingles. A radiant barrier may cause an increase in shingle temperature by 2 to 5 degrees Fahrenheit on a hot summer day. Given that shingle temperatures on a hot date are in the range of 160 to 190 degrees, this small increase is negligible and does not accelerate shingle degradation. Although roofing manufacturers were concerned about shingle failure in the years when radiant barriers were first used, it is no longer a concern.The Florida Solar Energy Center also conducted a study on the use of radiant barriers under shingled roofs and found that properly installed, radiant barriers do not void the warranty of shingles.