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Bonus room sub-floor


diverdave's Avatar
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Join Date: Sep 2006
Posts: 10

09-23-06, 04:56 PM   #1  
Bonus room sub-floor

Hello all,

First let me say that I love this site and I'm glad it's available. I'm in the process of finishing out the 200sq/ft Bonus room above our unheated attached garage. I want to insulate this room the best I can, but the one thing that I'm confused about is the flooring.

Right now there is a 3/4'' subfloor above an unheated attached garage without any insulation, and according to Memphis, TN code none is required even if I do finish it. I was going to put in R19 unfaced 6 1/4'' thick in a 7'' thick cavity (2x8's).

I'm just confused now whether or not I need to use a vapor barrier or not. I understand that the vapor barrier goes torwards the heated (living) area, I just know if I need one. I was thinking to be safe just put in the unfaced batts, lay down a 6mil plastic sheeting barrier, and then my 3/4'' subfloor.

What are your thoughts? Perhaps you may know the Code requirements for my area.

Thanks in advance I really appreciate any help.

Dave

 
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Concretemasonry's Avatar
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Join Date: Mar 2005
Posts: 6,125
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09-23-06, 06:05 PM   #2  
Bonus room sub-floor

Don't be fooled by codes - at best they are a minimum.

"You are not wrong going by the code, but you may not be right!"

Use as much insulation as you wish, even if the code says you do not need it. Vapor barrier on the warm side, whether you use insulation or not - the reason is that the empty cavity contains natural insulation (an air space) and you want the insulation outside the vapor barrier.


Dick

 
diverdave's Avatar
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09-23-06, 06:53 PM   #3  
Bonus room sub-floor

Thanks Dick,

Since faced insulation acts as the vapor barrier, and will cost alot more than unfaced (37.98 a batt @ 93'' faced vs 23.99 a batt un-faced) to do 200 sq/ft. Would it be okay to just use unfaced with 6mil sheeting on top? The price is much more attractive and it is serving the same purpose I believe. What do you think?

Dave

 
Ed Imeduc's Avatar
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09-23-06, 07:14 PM   #4  
Would it be okay to just use unfaced with 6mil sheeting on top?
Dont see why not
Go for it it will work

ED

 
diverdave's Avatar
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Join Date: Sep 2006
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09-23-06, 08:32 PM   #5  
Thanks

Thanks for all the folks,

As the project progesses I'm sure I'll have a few more questions, so thanks a lot for all the help.

Dave

 
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