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Insulating Garage-vapor barrior needed?


argekay's Avatar
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08-29-06, 04:09 AM   #1  
Insulating Garage-vapor barrior needed?

Hi and Thanks in advance for your time-
I am insulating an existing attached garage. The previous insulation was inferior, as it was installed in the 1950's, and was of low R value. I am installing R-13 in the exterior 2x4 walls, and R-19 in the 2x6 ceiling (all Kraft faced). The garage has a concrete floor. I will be using epoxy paint on the floor. Also- I will be installing electric radiant heat panels to keep the garage at around 45 degrees in the winter. There is no rot or moisture issue in the garage at present. My question is-do I need to install a polyethelene vapor barrier over the insulation, or do I just leave it without. Previously ther was no vapor barrier.This will be covered by 5/8" sheetrock.
Thanks.
Ray.

 
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em69's Avatar
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08-29-06, 04:21 AM   #2  
If you are adding heat to a space, then you need a VB.

 
argekay's Avatar
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08-29-06, 04:59 AM   #3  
thanks em69.

 
xiphias's Avatar
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09-05-06, 08:55 AM   #4  
Depends on your climate. Polyethylene is highly impermeable. Only used in specific climates. Elsewhere, kraft facing is generally considered appropriate.

Check out http://www.buildingscience.com/resources/walls/Vapor_Barriers_Wall_Design.pdf

the site is a gold mine.

 
Ed Imeduc's Avatar
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09-05-06, 09:21 AM   #5  
Use a poly V/B over the paper. I dont care how hard you try you cant get a seal on the walls with just paper back insulation. We put it on the walls and over any door or windows. Then dry wall after done cut the door and windows out of it. Hey you got clean windows and doors.

ED

 
em69's Avatar
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09-06-06, 04:54 AM   #6  
Posted By: xiphias Elsewhere, kraft facing is generally considered appropriate.
It may be appropriate in your area, but it is not superior to poly. Codes are the minimum building requirements, so it is always best to improve on them when building.

As Ed stated, it is impossible to get a good seal on the Kraft paper.


Posted By: xiphias Check out http://www.buildingscience.com/resources/walls/Vapor_Barriers_Wall_Design.pdf

the site is a gold mine.
Not in my opinion. I believe most people are misinterpreting the information on this site.

 
xiphias's Avatar
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09-06-06, 05:26 AM   #7  
Very well then.

 
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