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-   -   Insulate knee wall in Cape Cod (http://www.diychatroom.com/f103/insulate-knee-wall-cape-cod-181166/)

chimera451 06-02-2013 11:53 PM

Insulate knee wall in Cape Cod
 
Hello, hopefully someone will be able to help me with my renovation of a knee wall in a cape cod style house in Maryland (zone 4). I took some pictures to show you my situation.

http://i.imgur.com/JsmqSLJh.jpg

The general guidance seems to be that you would insulate the inside wall (#1) of the knee wall and the floor (#4 - the ceiling of the first floor).

The problem I have in my knee wall is that I have plumbing (hot and cold water supply and drain) running in the knee wall (not pictured as it is behind me in the pictures).

As far as ventilation, when I had a new roof put on they put some sort of edge vent. You can see it in this picture:

http://i.imgur.com/2vaHLS5h.jpg

Due to the plumbing, I'm thinking I should insulate along the roof and the exterior wall. Is this correct? (I started with this premise but on reading some more am worried this may not be right).

To provide a little more information, my roof is only 2x6 rafters and my exterior wall is 2x4. My interior walls are also 2x4. The house will be a rental so not looking to spend crazy amounts of money but want to make it somewhat efficient.

Please let me know if I can provide any other information. The album for all the pictures is located here: http://imgur.com/a/fx6O1
Any help is appreciated!

Windows on Wash 06-03-2013 06:06 AM

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.

chimera451 06-03-2013 06:38 AM

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?

chimera451 06-07-2013 10:39 AM

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

nicktools561 06-07-2013 11:16 AM

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!

Windows on Wash 06-08-2013 07:55 AM

Quote:

Originally Posted by chimera451 (Post 1196865)
Anyone have any suggestions - really looking for some help so I can get moving on this project! :)

See below.

Quote:

Originally Posted by nicktools561 (Post 1196892)
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).

Gary in WA 06-08-2013 10:48 PM

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

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

http://www.buildingscience.com/docum...n-roof-venting

Gary


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