Garage Door Kit Premium Energy-Saving Reflective Insulation

R-values relate more to mass type insulations or insulating materials that are installed in an enclosed air space. Radiant barriers are typically designed to work in vented attics, so their performance is not rated with an R-value; however, R-values are not the ONLY way to quantify resistance to heat flow. For example, a tree or an awning doesn't have an R-value, but it certainly can keep you cool. To simply put it, a radiant barrier is like putting a shade tree in your attic. Technically speaking, Silver Shield™ Radiant Barrier reflects 97% of the radiant heat and only emits 3% into the attic so unlike R-value, the lower the "E-value", or the less that it radiates into the attic, the better the radiant barrier. Silver Shield™ is the best-rated radiant barrier on the market.

A water vapor retarder may or may not be part of the design depending on the climate zone and the other building components used in that particular section of the building envelope. If air containing water vapor is allowed to come in contact with a cold surface, then condensation will likely occur. Water vapor transmission can also occur even if the building envelope is air sealed or has an effective and properly installed air barrier. Some insulation systems should include a water vapor retarder and some should allow vapor transmission. Building codes and climate zones generally dictate the use of a water vapor retarder -- in short, the envelope is a system and the use should be carefully considered by the building designer.