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Insulating a small section of Basement Walls in KS

Location = KS.  I'm planning to use 1/2" XPS Rigid Foam as a moisture barrier on a small section of 2 concrete basement walls for a finished family room (finished walls will cover less than 10% of total foundation walls).  Since it is such a small section of the overall foundation walls, I'm thinking about not insulating the finished 2x2 wall – between the XPS moisture barrier and the drywall.  Are there any downsides to that ?  Anything I should consider ?

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Posted 2014-06-23T23:35:59+0000  by DIY4BF19926KS DIY4BF19926KS

Hello DIY4BF19926KS, welcome to the Community.

The only reason for putting more insulation between the xps foam board you are using for a moisture barrier and the drywall would be to achieve a higher r-rating.  If you are enclosing the family room from the rest of the basement and you plan on heat that area exclusively, you may want to add insulation to all of that room’s walls.  But if the floor plan is open and you are not insulating the other wall there will be little benefit from adding to just those two walls.

 Here is a link to Owens Corning Residential installation guide that may help you understand the principles of home insulation and its benefits.

Thank you for your question and if you need any more assistance please send me a note.



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Best Answer

Posted 2014-06-24T17:27:49+0000  by Char_HD_CHI
Minor Update - did some measuring and the finished walls will be 20% of the total foundation lineal feet.  Still seems too little to insulate between XPS moisture barrier and drywall.  Unless there is another reason for putting the insulation between XPS and drywall.  Thanks!
Posted 2014-06-24T05:36:11+0000  by DIY4BF19926KS
I would strongly recommend reading what Building Science Corporation has to offer on basement finishing and insulation.  They have a number of document so you'll have to do a little looking.

Understand that if you have any kind of water problems in your basement now, they should be rectified before beginning your project.  XPS is not going to stop water infiltration.
Posted 2014-06-25T01:10:30+0000  by Adam444

Thanks Charlotte.  It's amazing the details that get glossed over when you are really close to the plan / issue.  The entire basement is heated / cooled.  And the Family Room is basically open on the 2 interior walls - a 6' entry on the 15' wall and 9' of sliding doors on the 17' wall.


Also thanks for the link.  I have been to the Owens Corning site, but other pages on the site.

Posted 2014-06-25T22:05:43+0000  by DIY4BF19926KS
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