# Walk-Out Basement Wall



## ddave23 (May 29, 2008)

I have received a lot of help here on my basement project. But I have read many articles and discussion on how to insulate my walk-out basement and i am stuck

We have the entire back side of our basement wall (2x6 stud/sheathing)that we are trying to figure out the best way to insulate.
The other walls in the basement are concrete 8ft high with 2x4 studing inch away and a 2x6 stud wall to the garage which is already insulated with kraft faced insulation R19.

I was wondering if you could use the Extruded Polystyrene Foam boards on the outside wood basement walk out wall not concrete? Or should i use the unfaced batts or faced batts and dyrwall over? 

Thanks for the help


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## Windows on Wash (Aug 30, 2011)

I was thinking through the exact same question in my basement today while getting some tools put together.

The foam is best suited to be against the concrete wall. If you have a 1" gap, you should be able to slide it between the studs and get it against the wall.

Applying it to the interior stud wall will create a complete vapor barrier if it is the polyethylene skinned type of XPS. 

The vapor barrier control of that board is most effectively placed directly against the interior concrete wall.

I may be misunderstanding your question so I apologize in advance if I did.


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## spring3100 (May 6, 2011)

I used ROXUL on the wood,above grade side of my walkout basement.

Bonus is that ROXUL in 2X6 studs gives you R-23 vs R-19,and it is moisture and mold resistant.


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## fenders (Apr 27, 2011)

question ; What did you guys do with the little concrete wall under the sliding door. Not sure what you call it but on my wlakout basement I have an 1-2 inches of concrete at thebase of my mostly insulated wall. 

Do you use a small piece of rigid foam all along ther bottom?


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## Windows on Wash (Aug 30, 2011)

Is the wall being framed out with 2x4/6's?

If not, I would leave it alone. People will invariably step on the foam and break it off it you don't have it protected with some sort of extension jamb.

It is not that big a thermal short circuit in the greater picture and there is alot more the basement that can take improvement first I would bet.


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## ddave23 (May 29, 2008)

spring3100 said:


> I used ROXUL on the wood,above grade side of my walkout basement.
> 
> Bonus is that ROXUL in 2X6 studs gives you R-23 vs R-19,and it is moisture and mold resistant.


I have never used ROXUL before...do I need a vapor barrier on top of the ROXUL?


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## benjamincall (Apr 25, 2008)

ddave23 said:


> I have never used ROXUL before...do I need a vapor barrier on top of the ROXUL?


Yes, on the inside:

http://www.roxul.com/residential/how+to+install+roxul

The insulation is porous and would allow warm, moisture-laden air from the interior to hit cold sheathing, creating a condensation problem.


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## Gary in WA (Mar 11, 2009)

Foamboard outside is good to raise the dew point of the wall cavity to prevent condensation; http://www.buildingscience.com/documents/reports/rr-0412-insulations-sheathings-and-vapor-retarders

http://www.greenbuildingadvisor.com...lating-minimum-thickness-rigid-foam-sheathing This way eliminates the plastic vapor barrier inside, reducing the Class required, if under the IRC; http://publicecodes.citation.com/icod/irc/2009/icod_irc_2009_6_sec001_par004.htm

http://publicecodes.citation.com/icod/irc/2009/icod_irc_2009_6_sec001_par005.htm
It also prevents thermal bridging of the wall studs/plates.

What will be the siding material?

Gary


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