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Transition from kneewall area to studs

Flyboy65's Avatar

Join Date: Nov 2008
Posts: 35

12-12-08, 02:42 PM   #1  
Transition from kneewall area to studs

We're totally gutting our upstairs. The stud cavities are all open, new outlet boxes in place, getting ready for an electrical rough in inspection.

The kitchen has a "lean to" 2/12 pitched roof that rises to one of the exterior upstairs walls. So, I've got about 2 1/2 feet of open space in the stud cavity into the "attic" above the kitchen. I guess it's kind of like a kneewall situation. There's faced R-19 butting up against the studs from the kitchen attic side...with the paper facing toward the upstairs room...it's not nailed or attached. The area above the kitchen is very well ventilated...to the point that right now it's "blowing" into that upstairs bedroom. I don't know if I can, or even want to, get in there...it was -11F last night.

How do I stop air infiltration without creating two layers of poly? I don't want the outside of the stud cavity to be "open" to that cold air, which would let air up and into my wall stud cavities.

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Bud9051's Avatar

Join Date: Oct 2008
Posts: 9,772

12-12-08, 05:44 PM   #2  
First some reading for you. Welcome To Home Energy Magazine Online
House wrap is an air and water barrier, but does allow moisture to pass and thus is not a vapor barrier. If you use it on the attic side of your insulation, you will stop some of that air flow. I say some, because there is still a billowing effect with a flexible material like that. Sheathing (plywood or OSB),just like the outside of your house is an air barrier, not a moisture barrier, if you can get some in there.

You mentioned r-19, one of our posters pointed out that spaces such as side attics are still attics and r-38 is just getting started, r-50 would be better.

The above link is long but really a great explaination on how to handle the little spaces like yours, and mine.

post back for more details if needed.


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