blanket insulation & r-value claims
I’ve been researching different insulation types lately(who isn’t) for a couple of home projects,& I came across a reflective blanket insulation that claims R-14.5 despite how thin it is. Anyone have exerience with this stuff?. I know that nothing performs up to its full r-value. The page is http://www.insulation4less.com/highr_FfmF.asp, & it’s shown being used in rafter & stud bays, seems hard to believe it would do the job of batts or rigid styrofoam. Thanks
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They are basing the claim on it's ability to reflect radiant heat. This is a good thing but not the only thing to be concerned about. You should have a good thermal barrier also. There are several ways that heat enters or escapes, radiation is only one of them.
That is an "effective rate" that is based on unrealistic applications. you would have to install a air space in front of it to acheive even that rate to amke use of the reflective properties. It can be good in certain applications or in conjunction with other materials.
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I wish this stuff would go away. In my last gov't job as energy advisor/analyst/energy regulation writer, I suggested taking companies like this to court for fraud but no one had the spine to support me. This material or other generics were being given a higher R value each successive time I ran into it. I thought what a great product......its R value goes up as it ages....by the time I die it will be R100!!!
Really though, as I have worked in the residential energy field since 1977, I have developed a list of 60-65 popular energy misconceptions that I have picked from up from the street.
John Straub P.Eng, Phd.(building scientist at U. of Waterloo in Ontario and a counterpart/aquaintance of Joe Lstiburek's of Building Science Corporation) said on a website of Environmental Building News that " we have known all about R values and heat loss for years but this stuff (foil) keeps coming back.....it keeps me ungainfully employed fighting the claims!!"
Thanks everyone for the very useful advice; just what I wanted to hear.
And u have to keep the dust off it.
Joe H
Exactly!! Can get some R value from it in a lab test setup with no wind, dirt, poor installation but in the real world?????
If it sounds to good to be true, it probably is!
One of my favourite quotes by Mark Twain (I believe):
"Common sense ain't all that common, is it?"