R-Value reccommendation

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  #1  
Old 01-10-04, 06:10 AM
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R-Value reccommendation

I live in Atlanta GA and according to the U.S. Department of Energy, they recommend an a R-value of 49 in the attic. When I checked around for some priceing, there was one contractor who seemed to know what he was talking about, said that he wouldn't recommend anything over R-38 since I wouldn't be gaining anything higher than that. Typically it catches my attention when someone selling a service suggests something cheaper than what I ask for so I started doing some research. I faxed the guy some information to back up what I was telling him but was wondering how they (The DOE) determine the recommendation of R-49 down here.

Sounds like they just went up in recent years...does anyone know why?

http://www.eere.energy.gov/consumeri...value_map.html
 

Last edited by bverdon; 01-10-04 at 06:20 AM.
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Old 01-10-04, 01:15 PM
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R49 is recommended attic insulation for new construction only, it's R38 for existing houses. See
http://www.ornl.gov/sci/roofs+walls/...on/ins_16.html
 
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Old 01-10-04, 05:48 PM
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Originally posted by marcusl
R49 is recommended attic insulation for new construction only, it's R38 for existing houses. See
http://www.ornl.gov/sci/roofs+walls/...on/ins_16.html

Wow...what's the difference? Why would they recommend that for an existing house? Strange...
 
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Old 01-11-04, 07:27 PM
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Just a guess: More is better for energy efficiency, but attics in old houses have 3-1/2" of insulation (R-13) and standard attic insulation batts to add later are R-25 giving R-38. New construction can be built with whatever is required--say, two R25 layers. I'm not a pro, though, maybe there are other reasons...
 
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