# Using xps and batts in basment



## AGWhitehouse (Jul 1, 2011)

un-faced to allow for moisture to move through the wall allowing it to dry...


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## Gary in WA (Mar 11, 2009)

The interior walls are insulated for ? Sound? Thermal?

From a 5 minute earlier answer: Use a foam poly sill sealer under the bottom plate for an air/thermal/capillary break to the slab. Foam air seal the rim joists for sure. Use regular (50 perms) drywall rather than water-resistant green board (25 perms) because if you have a basement water leak either board will probably need replacing. Also, the regular board won’t slow down the moving water vapor (½ as much as green board). You don’t want it condensing/molding inside the wall due to a low permeance material- vinyl wallpaper, oil based paint, or asphalt paper-faced insulation. 
R-10 continuous (foam board) insulation or R-13 cavity (batt) insulation is required as you are in Zone 5 or 6. Air seal the drywall (ADA of Building Science) to slow any basement air from reaching the colder concrete wall behind the foam (tape joints). 

http://www.buildingscience.com/documents/reports/rr-0202-basement-insulation-systems


Gary


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## Lilbear79 (Aug 8, 2011)

*What do you mean about the drywall, what is ( 50 perms ) drywall and how is it different from regular drywall? And could I just fasten 2" xps board to block walls with furring strips and drywall over that ? And as far as the interior walls that don't contact the block walls can I just insulate with batt faced insulation for a sound barrior on that? Does all this sound OK, As long as I seal and tape the xps and tape and mud the drywall.*
*Thanks Barry*


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## Gary in WA (Mar 11, 2009)

Use regular drywall.The wood wall needs to be as vapor-open as possible. Regular drywall has a perm rating of 50, water-resistant has one of 25-, so it stops the water from moving to dry inside the basement better---which you want: http://www.buildingscience.com/docu...rol-for-new-residential-buildings?full_view=1

Furring strips are fine if approved by your local B.D. Try to stop any basement air from reaching the concrete wall, air seal the drywall; http://www.buildingscience.com/documents/information-sheets/air-barriers-airtight-drywall-approach/

Personally, I would use rock wool or do a search for sound insulation at our site library at the top of every page in the white box. Sound blockage is best with material mass or disengaging the drywall from the wall with mechanical means. Some ideas to get you started; http://www.stcratings.com/assemblies.html

Gary


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## AGWhitehouse (Jul 1, 2011)

If you don't recommend moisture-resistant gwb in high-moisture basement spaces, do you not recommend it in shower rooms as well?


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## Jackofall1 (Dec 5, 2010)

The responses covered all that is necessary for the insulation of the basement wall, it just missed one thing.........Steelers room........really..... Detroit is going all the way this year baby..

Mark


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