# Insulate knee wall in Cape Cod



## Windows on Wash (Aug 30, 2011)

If there is plumbing in the kneewall area, the easiest thing to do is to treat it as conditioned space and insulate the roof.

That being said, you will effectively be cutting off the air flow to the upper attic and will need to provide some intake air (roof vents can do this) in order to balance the flow.


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## chimera451 (Jun 3, 2013)

Thanks for the reply! The upstairs part of the attic does have ridge venting along the very top. Will that be enough? I've seem some people mention that you need to leave 1" of airspace along the roof in the knee wall. Is that necessary or can I just insulate the whole 2x6 rafters of the roof?

So if I'm treating it as conditioned living space, I'm thinking I'll insulate the roof, exterior wall, and floor (#2, #3, #4 in the picture I posted). I'm thinking the floor to separate the less conditioned knee wall on the second floor from the first floor. Is that correct?


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## chimera451 (Jun 3, 2013)

Anyone have any suggestions - really looking for some help so I can get moving on this project!


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## nicktools561 (May 29, 2013)

I pretty sure you would want to just insulate the whole 2 x 6 rafters of the roof.. I wouldn't leave a gap. Let us know how the job is progressing!


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## Windows on Wash (Aug 30, 2011)

chimera451 said:


> Anyone have any suggestions - really looking for some help so I can get moving on this project!


See below.



nicktools561 said:


> I pretty sure you would want to just insulate the whole 2 x 6 rafters of the roof.. I wouldn't leave a gap. Let us know how the job is progressing!


I think that might be a mistake.

If you cut off the venting from below, how are you planning on getting intake air into the attic above.

Leave a 2" vent space from the vents you have pictured to the underside of the sheathing and all the way to the upper attic. You can create this via foam board (be sure to cover with code approved ignition and thermal barriers as required).


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## Gary in WA (Mar 11, 2009)

http://www.habitat.org/env/pdf/ceiling_and_attic.pdf

http://oikos.com/esb/51/sideattics.html

http://www.buildingscience.com/documents/published-articles/pa-crash-course-in-roof-venting

Gary


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