Posted By jonr on 06/04/2009 8:28 AM
> Mylar. The great thing
about this is it does not need an air gap to stop heat transfer because
it is non conductive of any kind of energy
Snake oil.
Also be careful of someone who sells you a .01 inch thick sheet of plastic and says it is R4 *per inch* (hoping you will forget to divide by 100).
 No kidding!?!
The weird thing is, some people who write that kind of stuff actually BELIEVE the hype!
Go ask NASA and the fire chief? (Yeah, go ask the fire chief how the fire hazard is reduced by installing radiant barrier under concrete slabs. )
People who actually measure stuff have much higher cred, and damned few of them are insulation installers. There's a reason ASTM C177 & C1158 tests were invented... Do the math- the rest is BS. Radiant barrier is one of the most mis-applied & overhyped insulation technologies out there (but some of the foam guys are trying!) Radiant barriers have their places, but none of those places is in direct contact with both the radiating & absorptive elements. (But on either side of low-density fiberglass, yes, it makes a measurable difference.)
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