radiant barrier


Old 09-09-01, 12:35 PM
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After reading many articles and posts, I'm convinced that homeowners should install some kind of radiant barrier in their attics to enjoy summer time comfort and energy savings. I just have a question about an idea I have. In the stores I've seen those reflective foil products (the kind sandwiched between plastic) that go for about $30/100sq ft!! What if you were to buy rosin paper, paint one side with reflective aluminum paint, and install it across the underside of the rafters? At my builders supply rosin paper is $8 for a 500 sq ft roll & I'd guess one gallon of paint at $15 to $20 should cover that much area. Appreciate any opinions on this idea.


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Old 09-10-01, 07:27 AM
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Funny you shuld ask that question, I just happen to sell and install radiant barriers.

The ansewer to your question is no, it will not work.
Aluminum reflects heat energy like a mirror reflects your image. It is the atomic stucture or the foil that actually reflects. That's why you can electro plate alum or gold on plastic, like NASA does, and still get superior performance.
It would be like painting a mirror with paint and then wondering why you can't see your reflection.

I have a single layer material that sells for $140.00/thou sf. + tax and freight. This for installing to the bottom of the rafters. If you live in an area outside the south west I have a two layer material that installs over the existing insulation. The latter is the most efficient.

Radiant barriers (RB) are not just for retrofit. I have been installing Rb's for 29 years in new homes and commercial and have not found a material nearly as good much less superior to RB. The high 95% efficiency is far superior of fiber glass at .05% efficiency. Comparing typically sized homes I have found that a fiberglass home will use about 40% more heat and Up to 200%+ more a/c. This is one reason why the US DOE and utility companies ignore or minimize its superiority.

I want to commend you for taking the time to invetigate the difference in materials. If more people did so, fibergass and celulose would soon be off the market.

I thank you for considering my opinion. If you require more info about installing or material source, let me know.

[Edited by rbisys on 09-10-01 at 10:50]

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