Insulation Ratings

Air conditioning, fans, and anything related to keeping it cool, such as insulation. This would include any posts generally discussing how to keep it cool, such as which types of blocks are better insulators.... ideal wall thickness for keeping an A/C house cool, etc.

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Insulation Ratings

Postby Greenside » Mon Aug 12, 2013 3:57 pm

I see microfibre ceiling insulation in rolls for use above ceilings in a wide range of brands and prices. The principle of R ratings I understand, but the variation seems very wide for the same kind of insulation (fibregalss or microfibre in a mylar bag) that I wonder if you can place any faith in them at all. I also notice that some are giving an R-t rating, rather than simply R; anyone know what that's about? I can't find a reference on Google.

Two products from Global House that I recently bought seem virtually identical and yet one claims an R-t value of 21 and the other an R value of 12, the former being about 30% more expensive.
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Re: Insulation Ratings

Postby John » Mon Aug 12, 2013 5:04 pm

R = Thermal resistance

RT = Total thermal resistance

RT would be used where a roof has several layers of insulation with RT being the total.
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Re: Insulation Ratings

Postby Greenside » Mon Aug 12, 2013 7:47 pm

So quoting Rt for a single layer product means that somewhere in the small print they'll say how many layers the figure is based on?
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