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Adding an air barrier to older brick house.


shane2977's Avatar
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08-30-16, 04:53 PM   #1  
Adding an air barrier to older brick house.

Hello, I live in southern Ontario and my house was built in the 1950's. I want to redo the insulation in the walls. I have already decided to remove the drywall and replace the insulation with R-20 batting. I can't afford spray foam.

Because the outside is brick, I really can't install an air barrier on the outside so I want to install one on the inside. I know the wall has to breath to prevent moisture build up. I was thinking of installing house wrap inside the wall against the outer panels. So there would be (from the outside to the inside) brick, panel board, house wrap, insulation, vapor barrier, drywall.

Any thoughts on this? Pro or Cons?

Thanks

 
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08-30-16, 05:55 PM   #2  
IMO, it would be a waste of time to try to put housewrap on the interior side of your exterior sheathing... too many seams around every stud. For a product like Tyvek to be an air barrier, all the seams and edges must be taped. I doubt trying it would do any good at all.

 
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08-30-16, 06:48 PM   #3  
Not a pro on brick, but your wall assembly might need/have an air gap between the brick and the panel board. Not sure what that panel board is. But the brick likes air flow behind it to help it dry.

As X said, I see no need for the house wrap in that location. House wrap is a drainage plane that allows moisture to dry to the outside. Your air barrier would be your drywall. Although the house wrap and a plastic vapor barrier may help as air barriers, they are full of holes.

As for the insulation, consider Roxul. Good application for it and it would allow drying to the outside.

Bud

 
shane2977's Avatar
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08-31-16, 05:22 AM   #4  
Thanks for the replies guys.

What I was thinking was to use a continues piece of house wrap, not to cut a piece for each cavity. I would just push it into each cavity using the insulation bat, then it would come out around the stud and into the next cavity. So the wall studs would be on the exterior side of the wrap. I would use minimal staples to hold.

I believe the exterior panels are a fiber board material.

The reason I'm asking about this is that I believe its really important to minimize any air flow through the insulation which will displace the heat trapped inside.

The brick has lots of small cracks in it and there is a lot of air movement in the walls as it is now. I can feel significant drafts around the outlets.

The vapor barrier will stop drafts into the house but won't stop the air from blowing through the insulation which will significantly reduce it R value.

Your thoughts?

 
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08-31-16, 06:18 AM   #5  
Still a crazy idea. And it might even be inviting condensation. In the winter, that cold air will follow the back of your housewrap all the way around to the inside of the studs where its warm, inviting condensation. You wont be able to seal the top or bottom edges of the housewrap, and that's likely where the majority of condensation will occur. Also housewrap is not a vapor barrier. It is vapor permeable and is only an air barrier when applied to the outside of the sheathing where all the edges can be sealed 100%.

 
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