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Discussion Starter #1
I have one wall in the living room to the outside of the building about 11 foot long and 8 foot high.

It was once a door way to the outside and was closed in apparently not that well done :(

The walls do not have the mil plastic between the sheetrock and studs like the new buildings are getting.

I believe it has R19 in the walls but because it's like 45 degrees and freezing I'm starting to wonder.

I'm going to redo it but since I just remodeled the inside of the living room tearing off the sheetrock is not an option.
I'm going to remove the siding and plywood from the outside to get access.

I used this method for another area but put in 2" Foam board with R-10 value turned out to not be super effective.

Question is :

Do I need to put in plastic on this one wall?
Should I opt for R19 faced instead?
If R19 is installed what other things can I do?
Should I install outside WRAP before closing it up?

any feedback would be great.
 

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Discussion Starter #3
Thanks I'm aware of the vapor retarder process can cause moisture in the walls, but I am also aware of a builder who puts on wrap on the outside behind the siding and 6 mil plastic behind the sheetrock.
This to me sounds bad.

Since my room doesn't have plastic behind the sheetrock I am opting for wrap on the outside since I am coming at this from the outside.

Also we only have cold walls on one wall so I might find the insulation is done wrong or something else bizarre.
 

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Exterior Construction
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Housewraps are not vapor barriers (Class 1 vapor retarder) in this case.

They are vapor permeable so drying can still happen to outside.

Depending on the foam that you use and the thickness, you will have a vapor barrier on the outside of the home.

If you don't have plastic beneath the drywall, you should be fine.
 

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Discussion Starter #5
Housewraps are not vapor barriers (Class 1 vapor retarder) in this case.

They are vapor permeable so drying can still happen to outside.

Depending on the foam that you use and the thickness, you will have a vapor barrier on the outside of the home.

If you don't have plastic beneath the drywall, you should be fine.

Knowing that foam board is a lower R value (10) at 2" thick does it make more sense to use batts insulation and house wrap or just to install foam with the house wrap
 

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Exterior Construction
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If you are removing the siding from the exterior, you should put a rigid foam across the exterior prior to re-siding to interrupt the thermal bridging and resultant drop in R-Value.

Using foam for inside the wall cavity is probably more trouble than it is worth between all the cutting and fitment. If you want to use foam, buy a 600 board foot spray foam kit and just spray the inside wall from the back side.

High density fiberglass or mineral wool is probably just as well.

I would put in cellulose, mineral wool, or unfaced fiberglass (high density), cover the exterior with a rigid foam, tape the seams, and re-side/cover.

Make sure you seal up the air barrier (drywall) from the backside with caulk/foam to prevent any air loss from the structure.
 
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