Top 5 Radiant Barrier Facts

RadiantGUARD® radiant barriers BLOCK 97% of the radiant heat, almost 30% MORE heat than the best reflective paint.  Read more about reflective radiant barrier paint.
Radiant barriers do NOT have R-Values but DO increase the R-Value of your existing insulation if already in place.  Read more about radiant barrier and R-Values.
Radiant barriers MUST have at least a 3/4" air space on at least one side for them to be effective via the properties of reflectivity and/or emissivity.  You cannot lay a radiant barrier on top of roof decking and then simply cover with further roofing materials like felt or shingles.  Read more about how radiant barriers work and  installation techniques.
When installing a radiant barrier on the attic floor, you MUST use a perforated radiant barrier to allow moisture laden air to pass from your living space through the barrier and out the attic avoiding condensation.  Read more about perforated radiant barriers.
Radiant barriers do NOT accelerate degradation of roof materials nor negate shingle warranties.  Read more about radiant barriers and shingle temperatures.
  Dust accumulation on a double-sided radiant barrier laid over the attic floor will affect the performance of the radiant barrier but performance will "not degrade nearly as much as would be expected from the significant increases in emissivity caused by small amounts of dust."  Read more about dust accumulation on radiant barriers (summary of conclusion is on page six).