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insulation


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03-12-00, 12:00 AM   #1  
when insulating 2x4 sidewalls why not use the 5-1/2" thick batts to achieve a higher "R" value?

 
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03-12-00, 01:32 AM   #2  
You only have 3.5" of insulation space in a 2X4 wall, and compacting insulation defeats its purpose. You will not gain any r-value cramming the 5.5" in a 3.5" space, just extra cost. Should use batts made for depth being insulated. Also, recommend using plastic sheeting over walls after installation for better moisture barrier, even if insulation has backing.Good Luck!

 
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03-12-00, 04:11 PM   #3  
OldGuy is correct about compressing the insulation. Insulation works by "loft" (trapped air). Compressing it reduces loft, thus reducing R-value.

Instead of using R-11 or R-19, you can use R-13 inside a 3 1/2" wall. Using a vapor barrier doesn't necessarily increase R-value, but does help keep cold out and heat in.

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