Vapor barrier...

[aansorge]

Should I put up a vapor barrier in my chase/alcove install? It is an exterior wall. I assume yes?

 

[aansorge]

I should add that the house is cedar siding, has some sort of paper under the cedar, is insulated with un-faced fiberglass insulation, and will have durock for the interior walls.

 

[begreen]

I don't think so, but will sit by with a bag of popcorn to see what the consensus is.

 

[webby3650]

I would guess that paper under the cedar is the vapor barrier. It's likely felt paper or tar paper. I wouldn't recommend plastic, I've removed a lot of drywall that had moisture trapped under the plastic.

 

[aansorge]

Rats....already covered with durock. I did call the local building inspector and asked him. He said to put up vapor barrier.

 

[webby3650]

Did you put up plastic over the fiberglass?
I really don't think you have anything to worry about, most all houses around here have plastic sheeting over the bats.

 

[aansorge]

I put the plastic over Roxul...

 

[webby3650]

I wouldn't sweat it too much. The biggest issues are when there is a good vapor barrier under the siding, and then another is added inside. Like plastic on the outside under the siding and then also under the drywall, doing this will trap moisture in the wall cavity.

 

[oldspark]

Yep vapor barrier on the warm side of insulation, if it gets past that it needs to have a place to go. The paper under the siding will breathe?

 

[aansorge]

I should look into it. The paper seemed like the type of material that would allow vapor through, but I should check into it. I rebuilt that area of the house last year due to moisture problems. I thought that the problem stemmed from the way the back porch was attached to the home, but now I'm beginning to wonder. I discovered I do have a small flashing issue around the chimney area (probably flashing) as I've been working on my Blaze King install. This was probably the cause of the siding rot I found but I should also investigate the paper.